Work plan:
1. The concept of biology, its relationship with other sciences ……………… ..2
14. Features of the structure of the plant cell ..................... 7
30. Penetration of nutrients into the cell. The concept of turgor, plasmolysis, plasmoplysis of microorganisms ...................... ... ... 13
45. Antibiotics and inhibitors. Routes of entry and their influence on the quality of milk. Measures to prevent their penetration into milk …………………………………………………………… 15
50. Microflora of plants and forages ……………………………… ... 18
66. Describe the causative agents of tuberculosis and brucellosis ... ..22
1. The concept of biology, its relationship with other sciences.
Science is a sphere research activities aimed at obtaining new knowledge about objects and phenomena. Science includes knowledge about the subject of study, its main task is to know it more fully and deeper. The main function of science is research. The subject of the study of teaching methods in biology is the theory and practice of teaching, upbringing and development of students in this subject.
The methodology of teaching biology, like any science, learns the objective laws of the processes and phenomena that it studies. Revealing their common patterns allows her to explain and predict the course of events and act purposefully.
The main features of science, as a rule, are the goals, the subject of its study, methods of cognition and forms of expression of knowledge (in the form of fundamental scientific provisions, principles, laws, laws, theories and facts, terms). The history of the formation and development of science, the names of scientists who enriched it with their discoveries are also important.
The goals facing the methodology of teaching biology are in line with the general pedagogical goals and objectives. Therefore, this technique is a special area of pedagogy, due to the specifics of the subject of research.
The methodology of teaching biology is based on general pedagogical provisions in relation to the study of biological material. At the same time, it integrates special (natural-scientific and biological), psychological-pedagogical, ideological, cultural and other professional-pedagogical knowledge, skills and attitudes.
The methodology of teaching biology determines the goals of education, the content of the academic subject "Biology" and the principles of its selection.
The goals of education, along with the content, process and result of education, are an important element of any pedagogical system... Education takes into account both social goals and the goals of the individual. Social goals are determined by the needs of a developing society. Personal goals take into account individual abilities, interests, needs for education, self-education.
The level of education, that is, the mastery of biological knowledge, skills and abilities that contribute to active and full-fledged inclusion in educational, labor, social activities;
The level of upbringing, which characterizes the system of world outlooks, beliefs, attitude to the world around, nature, society, personality;
The level of development, which determines the ability, the need for self-development and improvement of physical and mental qualities. The goal of general secondary biological education is determined taking into account the named values and such factors as:
Integrity of the human person;
Predictiveness, that is, the orientation of the goals of biological education towards current and future biological and educational values. Thus, general secondary biological education becomes more open to renewal and adjustment;
Continuity in the system of continuing education.
The methodology of teaching biology also notes that one of the most important goals of biological education is the formation of a scientific worldview based on the integrity and unity of nature, its systemic and level structure, diversity, and the unity of man and nature. In addition, biology is focused on the formation of knowledge about the structure and functioning of biological systems, about the sustainable development of nature and society in their interaction.
The object and subject of research are the most important concepts of any science. They are philosophical categories. The object expresses the content of reality, independent of the observer.
The subjects of scientific knowledge are various aspects, properties and relations of an object, fixed in experience and included in the process of practical activity. The object of the study of the methods of teaching biology is the teaching and educational (educational) process associated with this subject. The subject of research of the methodology is the goals and content educational process, methods, means and forms of training, education and development of students.
In the development of science, its practical application and the assessment of achievements, a rather significant role belongs to the methods scientific research... They are a means of knowing the subject under study and a way to achieve the goal. The leading methods of teaching biology are as follows: observation, pedagogical experiment, modeling, forecasting, testing, qualitative and quantitative analysis. pedagogical achievement... The named methods are based on experience, sensory cognition. but empirical knowledge is not the only source of reliable knowledge. Such methods of theoretical knowledge as systematization, integration, differentiation, abstraction, idealization, system analysis, comparison, generalization help to reveal the essence of an object and a phenomenon, their internal connections.
The structure of the content of the methodology of teaching biology has been scientifically substantiated. It is divided into general and private, or special, teaching methods: natural history, according to the courses “Plants. Bacteria. Mushrooms and Lichens ", at the course" Animals ", at the courses" Man "," General Biology ".
The general methodology of teaching biology considers the main issues of all biological courses: the concept of biological education, goals, objectives, principles, methods, means, forms, models of implementation, content and structures, stages, continuity, history of the formation and development of biological education in the country and the world; ideological, moral and eco-cultural education in the learning process; unity of content and teaching methods; relationship between forms educational work; integrity and development of all elements of the biological education system, which ensures the strength and awareness of knowledge, skills and abilities.
Private methodologies explore specific learning issues for each course, depending on the content teaching material and the age of the students.
The general methodology of teaching biology is closely related to all private biological methods. Her theoretical conclusions are based on private methodological research. And they, in turn, are guided by general methodological provisions for each training course... Thus, the methodology as a science is one, the general and special parts are inextricably combined in it.
RELATIONSHIP OF BIOLOGY TEACHING METHODS WITH OTHER SCIENCES.
The methodology of teaching biology, being a pedagogical science, is inextricably linked with didactics. This is a section of pedagogy that studies the patterns of assimilation of knowledge, abilities and skills and the formation of students' beliefs. Didactics develops educational theory and teaching principles common to all subjects. The methodology of teaching biology, which has long been established as an independent area of pedagogy, develops theoretical and practical problems of the content, forms, methods and means of teaching and upbringing, due to the specifics of biology.
It should be noted that didactics, on the one hand, relies in its development on the theory and practice of methodology (not only biology, but also other academic subjects), and on the other hand, it provides general scientific approaches to research in the field of methodology, ensuring the unity of methodological principles in study of the learning process.
The methodology of teaching biology is closely related to psychology, since it is based on the age characteristics of children. The methodology emphasizes that upbringing education can be effective only if it corresponds to the age development of students.
Biology teaching methodology is closely related to biological science. The subject "Biology" is synthetic in nature. It reflects almost all the main areas of biology: botany, zoology, physiology of plants, animals and humans, cytology, genetics, ecology, evolutionary teaching, the origin of life, anthropogenesis, etc. For the correct scientific explanation natural phenomena, recognition of plants, fungi, animals in nature, their determination, preparation and experimentation, good theoretical and practical training is required.
The goal of biological science is to gain new knowledge about nature through research. The purpose of the subject "Biology" is to give students knowledge (facts, patterns), obtained by biological science.
Biology teaching methodology is closely related to philosophy. It contributes to the development of a person's self-knowledge, understanding of the place and role. scientific discoveries in the system of general development of human culture, allows you to link disparate fragments of knowledge into a single scientific picture of the world. Philosophy is theoretical basis techniques, equips her scientific approach to the diverse aspects of training, education and development.
The connection of the methodology with philosophy is all the more important, since the study of the foundations of the science of biology about all kinds of manifestations of living matter at different levels of its organization aims at the formation and development of a materialistic worldview. The methodology of teaching biology solves this important problem gradually, from course to course, with expansion and deepening. biological knowledge, leading students to an understanding of natural phenomena, movement and development of matter, the surrounding world.
14. Features of the structure of the plant cell.
A plant cell has a nucleus and all organelles characteristic of an animal cell: endoplasmic reticulum, ribosomes, mitochondria, Golgi apparatus. At the same time, it differs from the animal cell in the following structural features:
1) a strong cell wall of considerable thickness;
2) special organelles - plastids, in which the primary synthesis of organic substances from mineral substances occurs due to the energy of light - photosynthesis;
3) a developed system of vacuoles, largely determining the osmotic properties of cells.
A plant cell, like an animal, is surrounded by a cytoplasmic membrane, but, in addition, it is limited by a thick cell wall consisting of cellulose. The presence of a cell wall is a specific feature of plants. She determined the low mobility of plants. As a result, the nutrition and respiration of the body began to depend on the surface of the body in contact with environment, which led in the process of evolution to a greater dismemberment of the body, much more pronounced than in animals. The cell wall has pores through which the channels of the endoplaemic network of neighboring cells communicate with each other.
The predominance of synthetic processes over the processes of energy release is one of the most characteristic features metabolism of plant organisms. Primary synthesis of carbohydrates from inorganic substances carried out in plastids.
There are three types of plastids:
1) leukoplasts - colorless plastids in which starch is synthesized from monosaccharides and disaccharides (there are leukoplasts that store proteins or fats);
2) chloroplasts - green plastids containing the pigment chlorophyll, where photosynthesis is carried out - the formation process organic molecules from inorganic due to the energy of light,
3) chromoplasts, including various pigments from the group of carotenoids, which determine the bright color of flowers and fruits. Plastids can transform into each other. They contain DNA and RNA, and an increase in their number is carried out by dividing in two.
The vacuoles are surrounded by a membrane and are re-evolved from the endoplasmic reticulum. Vacuoles contain dissolved proteins, carbohydrates, low molecular weight synthesis products, vitamins, and various salts. Osmotic pressure, created by substances dissolved in the vacuolar juice, leads to the fact that water enters the cell, which causes turgor - a stressed state of the cell wall. Thick elastic walls Cytology (from cyto… and… logic) is the science of the cell. Studies the structure and functions of cells, their connections and relationships in organs and tissues in multicellular organisms, as well as unicellular organisms... Investigating the cell as the most important structural unit of living things, cytology occupies a central position in a number of biological disciplines; it is closely related to histology, plant anatomy, physiology, genetics, biochemistry, microbiology, etc. cellular structure organisms was started by microscopists of the 17th century. (R. Hooke, M. Malpighi, A. Levenguk); in the 19th century. a single cell theory for the entire organic world was created (T. Schwann, 1839). In the 20th century. the rapid progress of cytology was facilitated by new methods (electron microscopy, isotope indicators, cell cultivation, etc.).
As a result of the work of many researchers, a modern cell theory was created.
The cell is the basic unit of the structure, functioning and development of all living organisms;
The cells of all unicellular and multicellular organisms are similar (homologous) in their structure, chemical composition, basic manifestations of vital activity and metabolism;
Reproduction of cells occurs by dividing them, each new cell is formed as a result of the division of the original (mother) cell;
In complex multicellular organisms, cells are specialized in their functions and form tissues; organs are composed of tissues, which are closely interconnected and subject to nervous and humoral regulation.
The cell theory is one of the most important generalizations of modern biology.
All living things on Earth, with the exception of viruses, are built of cells.
A cell is an elementary integral living system. It should be noted that the cell of an animal organism and the cell of a plant are not the same in their structure.
In a plant cell there are plastids, a shell (which gives strength and shape to the cell), vacuoles with cell sap.
Cells, despite their small size, are very complex. Research carried out over many decades has made it possible to reproduce a fairly complete picture of the structure of a cell.
The cell membrane is an ultramicroscopic film consisting of two monomolecular layers of protein and a bimolecular layer of lipids located between them.
Functions of the cell plasma membrane:
Barrier,
Communication with the environment (transport of substances),
Communication between tissue cells in multicellular organisms,
protective.
The cytoplasm is the semi-liquid medium of the cell, in which the organelles of the cell are located. The cytoplasm is composed of water and proteins. She is capable of moving at a speed of up to 7 cm / hour.
The movement of the cytoplasm within the cell is called cyclosis. Distinguish between circular and reticular cycloses.
Organelles are secreted in the cell. Organoids are permanent cellular structures, each of which performs its own function. Among them are:
Cytoplasmic matrix,
Endoplasmic reticulum,
Cell center,
Ribosomes,
Golgi apparatus,
Mitochondria,
Plastids,
Lysosomes,
1. Cytoplasmic matrix.
The cytoplasmic matrix is the main and most important part of the cell, its true internal environment.
The components of the cytoplasmic matrix carry out the processes of biosynthesis in the cell and contain the enzymes necessary for the production of energy.
2. Endoplasmic reticulum.
The entire inner zone of the cytoplasm is filled with numerous small channels and cavities, the walls of which are membranes similar in structure to the plasma membrane. These channels branch, connect to each other and form a network called the endoplasmic reticulum. ES is heterogeneous in its structure. Two types of it are known - granular and smooth.
3. Cell nucleus.
The cell nucleus is the most important part of the cell. It is found in almost all cells of multicellular organisms. The cells of organisms that contain a nucleus are called eukaryotes. The cell nucleus contains the DNA-substance of heredity, in which all the properties of the cell are encrypted.
In the structure of the nucleus, there are: the nuclear envelope, nucleoplasm, nucleolus, chromatin.
The cell nucleus performs 2 functions: storage of hereditary information and regulation of metabolism in the cell.
4. Chromosomes
The chromosome consists of two chromatids and after division of the nucleus becomes monochromatid. By the beginning of the next division, a second chromatid is completed on each chromosome. Chromosomes have a primary constriction on which the centromere is located; the constriction divides the chromosome into two arms of the same or different length.
Chromatin structures are DNA carriers. DNA consists of sections - genes that carry hereditary information and are transmitted from ancestors to descendants through germ cells. DNA and RNA are synthesized in chromosomes, which serves as a necessary factor in the transmission of hereditary information during cell division and the construction of protein molecules.
4. Cell center.
The cell center consists of two centrioles (daughter, maternal). Each has a cylindrical shape, the walls are formed by nine triplets of tubes, and in the middle there is a homogeneous substance. The centrioles are located perpendicular to each other. The function of the cell center is to participate in cell division in animals and lower plants.
5. Ribosomes
Ribosomes are ultramicroscopic organelles of a round or mushroom shape, consisting of two parts - subparticles. They do not have a membrane structure and are composed of protein and RNA. Subparticles are formed in the nucleolus. \
Ribosomes are universal organelles of all cells of animals and plants. Are in the cytoplasm in a free state or on the membranes of the endoplasmic reticulum; in addition, they are found in mitochondria and chloroplasts.
6. Mitochondria
Mitochondria are microscopic organelles with a two-membrane structure. The outer membrane is smooth, the inner one forms outgrowths of various shapes - cristae. In the matrix of mitochondria (a semi-liquid substance) there are enzymes, ribosomes, DNA, RNA. The number of mitochondria in one cell is from one to several thousand.
7. Golgi apparatus.
In the cells of plants and protozoa, the Golgi apparatus is represented by individual crescent or rod-shaped bodies. The Golgi apparatus includes: cavities bounded by membranes and located in groups (5-10 each), as well as large and small vesicles located at the ends of the cavities. All these elements make up a single complex.
Functions: 1) accumulation and transport of substances, chemical modernization,
2) the formation of lysosomes,
3) synthesis of lipids and carbohydrates on membrane walls.
8. Plastids.
Plastids are the power plants of the plant cell. They can transform from one species to another. There are several types of plastids: chloroplasts, chromoplasts, leukoplasts.
9. Lysosomes.
Lysosomes are microscopic single-membrane organelles of a round shape. Their number depends on the vital activity of the cell and its physiological state. The lysosome is a digestive vacuole that contains dissolving enzymes. In the case of starvation, the cells are digested some organelles.
In the event of destruction of the lysosome membrane, the cell digests itself.
The nutrition of the animal and plant cells occurs in different ways.
Large molecules of proteins and polysaccharides enter the cell by phagocytosis (from the Greek phagos - devouring and kitos - vessel, cell), and liquid drops - by pinocytosis (from the Greek pinot - I drink and kitos).
Phagocytosis is a way of feeding animal cells, in which nutrients enter the cell.
Pinocytosis is a universal way of feeding (for both animals and plant cells), in which nutrients enter the cell in a dissolved form.
A microscopic cell contains several thousand substances that are involved in a variety of chemical reactions. Chemical processes in a cell are one of the basic conditions for its life, development and functioning. All cells of animals and plant organisms, as well as microorganisms, are similar in chemical composition, which indicates the unity of the organic world.
Out of 109 elements of Mendeleev's periodic system, a significant majority of them are found in cells. The cell contains both macronutrients and microelements.
In conclusion, we will draw the main conclusions:
The cell is an elementary unit of life, the basis of the structure, life, reproduction and individual development of all organisms. There is no life outside the cell (except for viruses).
Most of the cells are arranged in the same way: they are covered with an outer membrane - the cell membrane and filled with a liquid - the cytoplasm. The cytoplasm contains a variety of structures - organelles (nucleus, mitochondria, lysosomes, etc.), which carry out various processes.
The cell comes only from the cell.
Each cell performs its own function and interacts with other cells, ensuring the vital activity of the body.
There are no special elements in the cell that are characteristic only of living nature. This indicates the connection and unity of the living and inanimate nature.
30. Penetration of nutrients into the cell. The concept of turgor, plasmolysis, plasmoptosis of microorganisms.
Power mechanism. The entry of nutrients into the bacterial cell is a complex physicochemical process, which is facilitated by a number of factors: the difference in the concentration of substances, the size of the molecules, their solubility in water or lipids, the pH of the medium, and permeability cell membranes and so on. Four possible mechanisms are distinguished in the penetration of nutrients into the cell.
The simplest method is passive diffusion, in which the entry of a substance into the cell occurs due to the difference in the concentration gradient (the difference in concentration on both sides of the cytoplasmic membrane). The size of the molecule is of decisive importance. Obviously, there are areas in the membrane through which small-sized substances can penetrate. One of these compounds is water.
Most of the nutrients enter the bacterial cell against the concentration gradient, therefore enzymes must be involved in this process and energy can be expended. One of these mechanisms is facilitated diffusion, which occurs when the concentration of the substance is higher outside the cell than inside. Facilitated diffusion is a specific process and is carried out by special membrane proteins, carriers, called permease, since they perform the function of enzymes and have specificity. They bind a molecule of a substance, transfer it unchanged to the inner surface of the cytoplasmic membrane and release it into the cytoplasm. Since the movement of a substance occurs from a higher concentration to a lower one, this process takes place without energy consumption.
The third possible mechanism of transport of substances has taken the name of active transport. This press is observed at low substrate concentrations in the environment and the transport of solutes is also carried out unchanged against the concentration gradient. Permeases are involved in the active transfer of substances. Since the concentration of a substance in a cell can be several thousand times higher than in the external environment, active transfer is necessarily accompanied by the expenditure of energy. Adenosine tri-phosphate (ATP), accumulated by the bacterial cell during redox processes, is consumed.
And, finally, with the fourth possible mechanism of nutrient transfer, radical translocation is observed - the active transfer of chemically altered molecules, which in general are not able to pass through the membrane. Permeases are involved in the transfer of radicals.
The release of substances from the bacterial cell occurs either in the form of passive diffusion (for example, water), or in the process of facilitated diffusion with the participation of permeases.
Organic matter is needed to feed soil microorganisms. There are two ways for organic matter to enter the soil - root exudates of plants with post-harvest residues and the introduction of organic matter into the soil from the outside, in the form of compost, manure, green manure, etc.
Turgor(from late lat. turgor swelling, filling), internal hydrostatic pressure in a living cell, causing tension in the cell membrane. In animals, the turgor of the cells is usually low, in plant cells, the turgor pressure maintains the leaves and stems (in herbaceous plants) in an upright position, gives the plants strength and stability. Turgor is an indicator of water content and the state of the water regime of plants. A decrease in turgor is accompanied by the processes of autolysis, wilting and aging of cells.
If the cell is in a hypertonic solution, the concentration of which is greater than the concentration of the cell sap, then the rate of diffusion of water from the cell sap will exceed the rate of diffusion of water into the cell from the surrounding solution. Due to the release of water from the cell, the volume of cell juice is reduced, turgor decreases. A decrease in the volume of the cellular vacuole is accompanied by the separation of the cytoplasm from the membrane - plasmolysis occurs.
Plasmolysis(from the Greek plasmas molded, shaped and ... lysis), in biology, the separation of the protoplast from the shell under the action of a hypertonic solution on the cell. Plasmolysis is characteristic mainly of plant cells with a strong cellulose membrane. Animal cells in a hypertonic solution shrink.
Plasmoptiz(plasma - + Greek ptisis crushing) - swelling of microbial
cells and destruction of their membranes in a hypotonic solution.
45. Antibiotics and inhibitors. Routes of entry and their influence on the quality of milk. Measures to prevent them from entering milk.
Antibiotics are a waste product of various microorganisms. Antibiotics have an inhibitory effect on the reproduction of other microbes and therefore are used to treat various infectious diseases. A group of antibiotics that block the synthesis of nucleic acids (DNA and RNA) is used as immunosuppressants, since in parallel with the suppression of bacterial reproduction, it inhibits the proliferation (reproduction) of cells of the immune system. Representatives of this group of drugs are Actinomycin
Particular attention should be paid to measures to prevent the ingress of antibiotics into animal products. Antibiotics can get into milk during the treatment of animals, as well as when feeding concentrated and other feed intended for pigs or biological industry waste containing mycelium and other antibiotics to lactating cows. Apparently, the possibility of deliberate addition of antibiotics to milk in order to reduce bacterial contamination of collected milk cannot be absolutely ruled out.
Several methods are used to detect inhibitory substances in milk. The simplest, most affordable and less laborious is biological. The essence of the method is to suppress the growth of lactic acid streptococcus sensitive to inhibiting substances, for example Str. thermo-philus added to the test milk sample containing an inhibiting substance. The result of the reaction is recorded by the color of the milk column into which the indicator is added. The initial color indicates a positive reaction, i.e., the presence of an inhibiting substance. However, milk contains in its composition the so-called natural inhibiting substances, such as lactoferrin, properdin, lysozymes and many others, which also inhibit the growth of lactic acid bacteria and in particular Str. thermophilus. Therefore, although it is assumed that most natural inhibitory substances should be destroyed when the sample is heated for 10 min at 85 ° C, the biological method is not specific and additional studies are required to establish the type of added chemical or antibiotic. For this reason, until now, not a single biological method, with the help of which it would be possible to identify inhibitory substances in
The problem of milk contamination with inhibitory substances, including antibiotics, is becoming more and more important every year.
Inhibitory substances include antibiotics, sulfonamides, nitrofurans, nitrates, preservatives (formalin, hydrogen peroxide), neutralizing (soda, sodium hydroxide, ammonia), detergents and disinfectants, etc.
The presence of antibiotic residues is a particular danger to humans and a serious problem for the dairy industry, as they can disrupt the production process by inhibiting the starter microflora. This leads to serious financial losses. But the most dangerous are the consequences of the ingestion of antibiotic residues in the human body.
Pesticides used to protect plants from pests are also dangerous to human and animal health. Milk containing residual amounts is not accepted for processing. Pesticides differ in their specific action. Chlorine insecticides are persistent and lipolytic and are therefore particularly hazardous in food. Organic esters phosphoric acid and carbamates do not accumulate in food and are not of interest for milk hygiene. Herbicides and fungicides are generally not very resistant. Their residues in milk have not yet been found, therefore, it is impractical to determine their content.
The manifestation of the inhibitory properties of milk is influenced by a variety of factors. Possible sources of inhibitors getting into milk are: violations in milk rejection in the treatment of animals; sanitization of milking and dairy equipment; the use of low-quality feed; the ingress of a number of chemicals into the feed.
The inhibitory properties of milk can be influenced by the feeding of the cows and the quality of the feed. The dosage of chemical reagents should be strictly observed when preserving silage. The inhibitory properties of milk can be influenced by the presence of an increased content of nitrates or nitrites in feed.
In order to prevent the ingress of residual amounts of detergents, detergents, disinfectants and disinfectants into milk and their possible influence on the results of the determination of inhibiting substances, the sanitary treatment of milking and dairy equipment must be carried out strictly in accordance with sanitary rules. In case of positive reactions to the presence of residual amounts of sanitary products on the surface of milking and dairy equipment
it is necessary to rinse it again with water.
One of the ways that antibiotics and other drugs get into milk is through intramuscular injection. Antibiotics and sulfonamides are most commonly seen when cows are being treated for mastitis.
Taking into account the specificity of the effect of various inhibiting substances both on the health of humans and animals, and on the technological properties of milk, the solution to the problem under consideration largely depends on the development and implementation of highly effective, highly specific methods of its control for the presence of inhibiting substances. It is not enough to establish their presence, it is important to determine not only the type, but also the specific substance that caused the manifestation of the inhibitory properties of milk. This allows you to analyze the situation in order to find out the possible source of this substance getting into it.
Currently, the country has GOST standards on methods for the determination of inhibiting substances in milk. In particular, at dairy enterprises it is possible to determine the presence of soda, ammonia, hydrogen peroxide in it.
Another important condition for ensuring the safety of milk, including its inhibitory properties, is quality control exclusively in independent testing laboratories. In this regard, there is a need to create a state regulatory framework, including a system of settlements for raw milk between rural producers and purchasing factories based on measurements of milk quality by such laboratories.
50. Microflora of plants and feed.
Epiphytic microflora.
A varied microflora, called epiphytic, is constantly present on the surface parts of plants. On stems, leaves, flowers, fruits, the following non-spore types of microorganisms are most often found: Bact, herbicola makes up 40% of all epiphytic microflora, Ps. fluorescens - 40%, lactic acid bacteria - 10%, the like - 2%, yeast, mold fungi, cellulose, butyric acid, thermophilic bacteria -
After mowing and loss of plant resistance, as well as due to mechanical damage to their tissues, epiphytic and, first of all, putrefactive microflora, multiplying intensively, penetrates into the thickness of plant tissues and causes their decomposition. That is why crop production (grain, coarse and succulent fodder) is protected from the destructive effect of epiphytic microflora by various conservation methods.
It is known that plants have bound water, which is part of their chemical substances, and free water, which is drip-liquid. Microorganisms can multiply in the plant mass only if there is free water in it. One of the most common and affordable methods for removing free water from crop products and therefore preserving them is drying and ensiling.
Drying grain and hay provides for the removal of free water from them. Therefore, microorganisms cannot multiply on them as long as these products are dry.
Freshly cut, unstable grass contains 70 - 80% water, dried hay only 12-16%, the remaining moisture is bound to organic substances and microorganisms and is not used. During the drying of hay, about 10% of organic matter is lost, mainly during the decomposition of proteins and sugars. Especially large losses of nutrients, vitamins and mineral compounds occur in dried hay in swaths (windrows) when it rains frequently. Distilled rain water washes them up to 50%. Significant losses of dry matter occur in the grain during its self-heating. This process is due to thermogenesis, that is, the creation of heat by microorganisms. It arises because thermophilic bacteria use for their life only 5-10% of the energy of the nutrients they consume, and the rest is released into their environment - grain, hay.
Silage of fodder. When growing forage crops (corn, sorghum, etc.) from one hectare, it is possible to obtain significantly more feed units in green mass than in grain. In terms of starch equivalent, the nutritional value of green mass during drying can be reduced to 50%, and during ensiling only up to 20%. When ensiling, small leaves of plants with a high nutritional value are not lost, and when dried, they fall off. Silage can also be placed in variable weather. Good silage is a succulent, vitamin, milk-producing forage.
The essence of ensiling is that lactic acid microbes that decompose sugars with the formation of lactic acid, accumulating up to 1.5-2.5% of the silage weight, intensively multiply in the crushed green mass in the container. At the same time, acetic acid bacteria multiply, converting alcohol and other carbohydrates into acetic acid; it accumulates 0.4-0.6% by weight of the silage. Lactic and acetic acids are a strong poison for putrefactive microbes, so their reproduction stops.
Silage remains in good condition for up to three years, as long as it contains at least 2% lactic and acetic acids, and the pH is 4-4.2. If the reproduction of lactic acid and acetic bacteria weakens, then the concentration of acids decreases. At this time, yeast, molds, butyric acid and putrefactive bacteria begin to multiply at the same time, and the silage deteriorates. Thus, obtaining good silage depends primarily on the presence of sucrose in the green mass and the intensity of the development of lactic acid bacteria.
In the process of silage maturation, three microbiological phases are distinguished, characterized by a specific species composition of microflora.
The first phase is characterized by the multiplication of mixed microflora with some predominance of putrefactive aerobic non-spore bacteria - Escherichia coli, Pseudomonas, lactic acid microbes, yeast. Spore-bearing putrefactive and butyric acid bacteria multiply slowly and do not prevail over lactic acid bacteria. The main medium for the development of mixed microflora at this stage is plant sap, which is released from plant tissues and fills the space between the crushed plant mass. This contributes to the creation of anaerobic conditions in the silage, which inhibits the development of putrefactive bacteria and favors the reproduction of lactic acid microbes. The first phase with dense storage of silage, that is, under anaerobic conditions, lasts only 1-3 days, with loose storage under aerobic conditions, it is longer and lasts 1-2 weeks. During this time, the silage is heated by intensive aerobic microbiological processes. The second phase of silage maturation is characterized by rapid multiplication of lactic acid microbes, and at first, predominantly coccal forms develop, which are then replaced by lactic acid bacteria.
Due to the accumulation of lactic acid, the development of all putrefactive and butyric acid microorganisms stops, while their vegetative forms die, only spore-bearing ones remain (in the form of spores). With full observance of the technology of silage in this phase, homofermentative lactic acid bacteria multiply, forming only lactic acid from sugars. In case of violation of the technology of silage filling, when in it. contains air, the microflora of heteroenzymatic fermentation develops, resulting in the formation of unwanted volatile acids - butyric, acetic, etc. The duration of the second phase is from two weeks to three months.
The third phase is characterized by the gradual death of lactic acid microbes in the silage due to the high concentration of lactic acid (2.5%). At this time, the ripening of the silage is completed, a conditional indicator of its suitability for feeding is the acidity of the silage mass, which decreases to pH 4.2 - 4.5 (Fig. 37). Under aerobic conditions, mold and yeast begin to multiply, which break down lactic acid, butyric acid and putrefactive bacteria germinating from the spores use this, as a result the silage becomes moldy and rotten.
Silage defects of microbial origin. Failure to comply with the proper conditions for laying and storing the silage will cause certain defects.
Decay of silage, accompanied by significant self-heating, is noted when it is loosely laid and insufficiently compacted. The rapid development of putrefactive and thermophilic microbes is facilitated by the air in the silo. As a result of protein decomposition, silage acquires a putrid, ammonia-like odor and becomes unusable.
acquires a putrid, ammoniacal odor and to feeding. Decay of silage occurs in the first microbiological phase, when the development of lactic acid microbes and the accumulation of lactic acid, suppressing putrefactive bacteria, are delayed. To stop the development of the latter, it is necessary to lower the pH in the silage to 4.2-4.5. The rotting of the silage is caused by Er. herbicola, E. coli, Ps. aerogenes. P. vulgaris, B. subtilis, Ps. fluorescens as well as molds.
Rancidity of silage is caused by the accumulation of butyric acid in it, which has a sharp bitter taste and an unpleasant odor. In a good silage, butyric acid is absent, in a silage of average quality it is found up to 0.2%, and in an unsuitable for feeding - up to 1%.
The causative agents of butyric acid fermentation are capable of converting lactic acid into butyric acid, as well as causing putrefactive decomposition of proteins, which aggravates their negative effect on the quality of silage. Butteric acid fermentation is manifested with the slow development of lactic acid bacteria and insufficient accumulation of lactic acid, at a pH above 4.7. With the rapid accumulation of lactic acid in the silage up to 2% and pH 4-4.2, butyric acid fermentation does not occur.
The main causative agents of butyric acid fermentation in silage: Ps. fluo-rescens, Cl. pasteurianum, Cl. felsineum.
Peroxidation of silage is observed during vigorous reproduction of acetic acid, as well as putrefactive bacteria capable of producing acetic acid. Acetic acid bacteria multiply especially intensively in the presence of ethyl alcohol in the silage, accumulated by alcoholic fermentation yeast. Yeast and acetic acid bacteria are aerobes; therefore, a significant content of acetic acid in the silage and, consequently, its peroxidation is noted in the presence of air in the silo.
Silage mold occurs when there is air in the silo, which favors the intensive development of mold and yeast. These microorganisms are always found on plants, therefore, under favorable conditions, their rapid reproduction begins.
Rhizosphere and epiphytic microflora can play a negative role as well. Root crops are often affected by rot (black - Alternaria radicina, gray - Botrutus cinirea, potato - Phitophtora infenstans). Excessive activity of butyric acid fermentation pathogens leads to spoilage of silage. On vegetative plants, ergot (claviceps purpurae) reproduce, causing the disease ergotism. Mushrooms cause toxicosis. The causative agent of botulism (Cl. Votulinum), getting into the feed with soil and feces, causes severe toxicosis, often fatal. Many fungi (Aspergillus, Penicillum, Mucor, Fusarium, Stachybotrus) colonize food, multiplying under favorable conditions, and cause acute or chronic toxicosis in animals, often accompanied by nonspecific symptoms.
Microbiological preparations are used in the diets of animals and birds. Enzymes improve the absorption of feed. Vitamins and amino acids are obtained on a microbiological basis. Use of bacterial protein is possible. Fodder yeast is a good protein and vitamin feed. Yeast contains an easily digestible protein, provitamin D (zgosterol), as well as vitamins A, B, E. Yeast multiplies very quickly, therefore, in industrial conditions, it is possible to obtain a large amount of yeast mass when cultivated on molasses or saccharified fiber. At present, in our country, dry feed yeast is prepared in large quantities. For their manufacture, a culture of feed yeast is used.
66. Describe the causative agents of tuberculosis and brucellosis.
Brucellosis – a disease that affects not only cattle, but also pigs, rats and other animals. The causative agents are bacteria of the genus Brucella. These are small, immobile coccoid bacteria, gram-negative, do not form spores, aerobes. Contain endotoxin. The extreme limits of growth are 6-450C, the temperature optimum is 370C. When heated to 60-650C, these bacteria die in 20-30 minutes, when boiled - after a few seconds. Brucella is characterized by high viability: in dairy products (feta cheese, cheese, butter) they are stored for several months. The incubation period is 1-3 weeks or more. Milk from the foci of this infection is pasteurized at elevated temperatures (at 700 C for 30 minutes), boiled for 5 minutes or sterilized.
Brucellosis - a chronic disease of animals. It is detected in milk by a ring test based on the detection of the corresponding antibodies. On farms, unfavorable for brucellosis, it is prohibited to export milk from a healthy herd in a non-disinfected
Such milk is pasteurized and either exported to the dairy or used inside the farm. Milk from cows that respond positively to
brucellosis, boiled and used for on-farm needs.
Tuberculosis – cause mycobacteria of the genus Mycobacterium, related to actinomycetes. The shape of the cells is variable: rods are straight, branched and curved. Aerobes, immobile, do not form spores, but due to the high content of mycolic acid and lipids, they are resistant to acids, alkalis, alcohol, drying, and heating. They are stored in dairy products for a long time (in cheese - 2 months, in butter - up to 3 months). Sensitive to effects sunlight, ultraviolet rays, high temperature: at 70 ° C they die after 10 minutes, at 1000 ° C - after 10 seconds. Tuberculosis differs from other infections by a long incubation period - from several weeks to several years. In order to prevent this infection, it is not allowed to use milk from sick animals for food.
Tuberculosis - a chronic disease of animals. Standing out with milk
mycobacterium tuberculosis, which have a wax coating, are able to co-
stored in the external environment. Milk from a tuberculosis-dysfunctional farm is pasteurized directly on the farm at a temperature of 85 ° C for 30 minutes.
or at a temperature of 90 ° C for 5 minutes. Disinfected in this way
bom milk, obtained from animals of healthy groups, sending
goes to the dairy, where it is re-pasteurized and taken as a second
variety. Milk from animals that respond positively to tuberculin,
disinfected by boiling, after which they are used for fattening young
nyaka. Milk obtained from animals with clinical signs of tu-
berculosis, are used in the diet of fattening animals after 10
boiling for a minute. Milk is destroyed with udder tuberculosis.
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1. Definition of biology as a science. The relationship of biology with other sciences. The importance of biology for medicine. Definition of the concept of "life" at the present stage of science. Fundamental properties of living things.
Biology(Greek bios - "life"; logos - doctrine) - the science of life (wildlife), one of the natural sciences, the subject of which is living beings and their interaction with the environment. Biology studies all aspects of life, in particular the structure, functioning, growth, origin, evolution and distribution of living organisms on Earth. Classifies and describes living things, the origin of their species, interaction with each other and with the environment.
Relationship of biology with other sciences: Biology is closely related to other sciences and sometimes it is very difficult to draw a line between them. The study of the vital activity of a cell includes the study of molecular processes occurring inside a cell, this section is called molecular biology and sometimes refers to chemistry and not to biology. Chemical reactions occurring in the body are studied by biochemistry, a science that is much closer to chemistry than to biology. Many aspects of the physical functioning of living organisms are studied by biophysics, which is very closely related to physics. The study of a large number of biological objects is inextricably linked with such sciences as mathematical statistics. Sometimes ecology is singled out as an independent science - the science of the interaction of living organisms with the environment (living and inanimate nature). The science that studies the health of living organisms has long stood out as a separate area of knowledge. This area includes veterinary medicine and a very important applied science- medicine responsible for human health.
The importance of biology for medicine:
Genetic research has made it possible to develop methods for early diagnosis, treatment and prevention of hereditary human diseases;
Selection of microorganisms makes it possible to obtain enzymes, vitamins, hormones necessary for the treatment of a number of diseases;
Genetic engineering allows the production of biologically active compounds and drugs;
Definition of the concept of "life" at the present stage of science. Fundamental properties of living things: It is rather difficult to give a complete and unambiguous definition of the concept of life, given the huge variety of its manifestations. Most of the definitions of the concept of life, which have been given by many scientists and thinkers over the centuries, took into account the leading qualities that distinguish living from non-living. For example, Aristotle said that life is the "nutrition, growth and decrepitude" of the organism; AL Lavoisier defined life as a "chemical function"; GR Treviranus believed that life is "a stable uniformity of processes with a difference in external influences." It is clear that such definitions could not satisfy scientists, since they did not reflect (and could not reflect) all the properties of living matter. In addition, observations indicate that the properties of living things are not exclusive and unique, as it seemed before, they are separately found among inanimate objects. AI Oparin defined life as "a special, very complex form of motion of matter." This definition reflects the qualitative originality of life, which cannot be reduced to simple chemical or physical laws. However, even in this case, the definition is general in nature and does not reveal the specific originality of this movement.
F. Engels in his "Dialectics of Nature" wrote: "Life is a way of existence of protein bodies, the essential moment of which is the exchange of matter and energy with the environment."
For practical use, those definitions are useful, which contain the basic properties that are necessarily inherent in all living forms. Here is one of them: life is macromolecular open system, which is characterized by a hierarchical organization, the ability to self-reproduction, self-preservation and self-regulation, metabolism, a finely regulated flow of energy. According to this definition life is a nucleus of order, spreading in a less orderly universe.
Life exists in the form of open systems. This means that any live form it is not closed only on itself, but constantly exchanges matter, energy and information with the environment.
2. Evolutionarily determined levels of life organization: There are such levels of organization of living matter - levels of biological organization: molecular, cellular, tissue, organ, organismic, population-specific and ecosystem.
Molecular level of organization- this is the level of functioning of biological macromolecules - biopolymers: nucleic acids, proteins, polysaccharides, lipids, steroids. From this level begin critical processes vital functions: metabolism, energy conversion, transmission of hereditary information. This level is studied by: biochemistry, molecular genetics, molecular biology, genetics, biophysics.
Cell level- this is the level of cells (cells of bacteria, cyanobacteria, unicellular animals and algae, unicellular fungi, cells of multicellular organisms). A cell is a structural unit of living things, a functional unit, a unit of development. This level is studied by cytology, cytochemistry, cytogenetics, microbiology.
Tissue organization level- This is the level at which the structure and functioning of tissues is studied. This level is investigated by histology and histochemistry.
Organ level of organization- this is the level of organs of multicellular organisms. This level is studied by anatomy, physiology, embryology.
Organizational level of organization- this is the level of unicellular, colonial and multicellular organisms. The specificity of the organismic level is that at this level, decoding and implementation of genetic information, the formation of characteristics inherent in individuals of a given species, takes place. This level is studied by morphology (anatomy and embryology), physiology, genetics, paleontology.
Population-specific level- This is the level of aggregates of individuals - populations and species. This level is studied by systematics, taxonomy, ecology, biogeography, and population genetics. At this level, the genetic and ecological characteristics of populations, elementary evolutionary factors and their influence on the gene pool (microevolution), the problem of species conservation are studied.
Biogeocenotic level of life organization - represented by a variety of natural and cultural biogeocenoses in all environments ... Components- Populations of various species; Environmental factors ;
Food webs, flows of substances and energy ;
Basic processes; Biochemical circulation and energy flow that sustain life ;
Movable balance between living organisms and the abiotic environment (homeostasis) ;
Providing living organisms with living conditions and resources (food and shelter). Sciences conducting research at this level: Biogeography, Biogeocenology Ecology
Biosphere level of life organization
It is represented by the highest, global form of organization of biosystems - the biosphere. Components - Biogeocenoses; Anthropogenic impact; Basic processes; Active interaction of living and non-living matter of the planet; Biological global circulation of substances and energy;
Active biogeochemical participation of man in all processes of the biosphere, his economic and ethnocultural activities
Sciences conducting research at this level: Ecology; Global ecology; Space ecology; Social ecology.
3. Man in the system of nature. The specificity of the manifestation of the biological and social in a person.
Man belongs to the animal kingdom, since he uses ready-made substances for nutrition, that is, heterotrophic. Its cells do not have cellulose membranes, there are no chloroplasts - that is, it consists of typically animal cells.
Man belongs to: -Chordate type, since the embryo has a notochord, gill slits in the pharyngeal cavity, dorsal (dorsal) hollow neural tube and bilateral symmetry of the body.
To the subtype of vertebrates, since it develops a vertebral column from the vertebrae, a heart on the abdominal side of the body, two pairs of limbs.
To the class of mammals, since it is warm-blooded, the mammary glands are developed; due to the presence of hair on the surface of the body.
To the placental subclass: the development of the baby inside the mother's body, the nutrition of the fetus through the placenta. From a biological point of view, man is one of the mammalian species belonging to the primate order, the narrow-nosed suborder.
Natural and social in a person: In accordance with Karl Marx's characterization of the essence of man as a set of social relations, he appears to be a social being. At the same time, man is a part of nature. From this point of view, people belong to the highest mammals, forming a special kind of Homo sapiens, and, therefore, a person turns out to be a biological being. Like any biological species, Homo sapiens is characterized by a certain set of species characteristics. Each of these characters in different representatives of the species can vary within fairly large limits, which is normal in itself. Statistical methods make it possible to identify the most probable, widespread meanings of each species trait. Social processes can also influence the manifestation of many biological parameters of a species. For example, the average "normal" life expectancy of a person, according to modern science, is 80-90 years old, if he does not suffer from hereditary diseases and does not become a victim of causes of death external to his body, such as infectious diseases or diseases caused by an abnormal state of the environment, accidents, etc. This is the biological constant of the species, which, however, changes under the influence of social laws. As a result, real (as opposed to "normal") average duration life increased from 20-22 years in antiquity to about 30 years in the 18th century, 56 years in Western Europe by the beginning of the XX century and 75-77 years - in the most developed countries at the end of the XX century. The duration of childhood, adulthood and old age of a person is biologically determined; the age at which women can give birth to children is set (on average, 15-49 years); the ratio of births of one child, twins, etc. is determined. The sequence of such processes in development is biologically programmed human body, as the ability to assimilate various types of food, to master the language at an early age, the appearance of secondary sexual characteristics and much more. According to some reports, it is inherited, that is, biologically determined, and giftedness different people in various activities (music, mathematics, etc.). Like other biological species, the species Homo sapiens has stable variations (varieties), which are designated, when it comes to humans, most often by the concept of race. Racial differentiation of people is associated with the fact that groups inhabiting different regions of the planet have adapted to the specific features of their habitat, and this was expressed in the emergence of specific anatomical, physiological and biological characteristics. But referring to a single biological species Homo sapiens, a representative of any race has such biological parameters characteristic of this species that allow it to successfully participate in any of the spheres of life human society... If we talk about human prehistory, then the species Homo sapiens is the last stage in the development of the genus Homo known today. In the past, our predecessors were other species of this genus (such as Homo habilis- a capable person; Homo erectus - Homo erectus, etc.), science does not yet give an unambiguous genealogy of our species. Biologically, each of the human individuals who have ever lived or are living now is unique, unique, because the set of genes received from their parents is unique (with the exception of identical twins inheriting an identical genotype). This uniqueness is enhanced by the interaction of social and biological factors in the process of individual human development.
4. Precellular level of organization of living matter. Viruses.
VIRUSES- non-cellular life forms. Viruses are 50 times smaller than bacteria, they are on the verge of living and non-living. But if they are considered alive, then they will turn out to be the most numerous form of life on Earth.
Viruses are different from all other organisms:
2. They contain only one type of nucleic acid - either RNA or DNA.
3. They have a very limited number of enzymes, use the host's metabolism, its enzymes, the energy obtained during the metabolism in the host's cells. Among viral diseases - influenza, encephalitis, measles, mumps, rubella, hepatitis, AIDS.
The question is often asked: "Are viruses alive?" If we consider a living structure that possesses genetic material (DNA or RNA) and is capable of reproducing itself, then we can say that viruses are alive. If we consider a living structure with a cellular structure, then the answer should be negative. It should also be noted that viruses are unable to reproduce themselves outside the host cell. They are on the very border between the living and the inanimate. And this once again reminds us that there is a continuous spectrum of ever increasing complexity, which starts with simple molecules and ends with the most complex closed systems of cells.
Behavior
Structure
Viruses are very simple. They consist of a piece of genetic material, either DNA or RNA, that makes up the core of the virus, and a protective protein envelope that surrounds this core, which is called the capsid.
A fully formed infectious particle is called a virion. Some viruses, such as herpes or influenza viruses, also have an additional lipoprotein membrane that arises from the plasma membrane of the host cell. Unlike all other organisms, viruses do not have a cellular structure.
The envelope of viruses is often built from identical repeating subunits - capsomeres. Structures with high degree symmetries capable of crystallizing. This makes it possible to obtain information about their structure using both crystallographic methods based on the use of X-rays and electron microscopy. As soon as the subunits of the virus appear in the host cell, they immediately show the ability to self-assemble into a whole virus. Self-assembly is also characteristic of many other biological structures; it is of fundamental importance in biological phenomena.
Spiral symmetry. The best illustration of helical symmetry is the tobacco mosaic virus (TMV) containing RNA. 2130 identical protein subunits together with RNA make up a single integral structure - the nucleocapsid. In some viruses, such as mumps and influenza viruses, the nucleocapsid is surrounded by an envelope.
Bacteriophages. Viruses that attack bacteria form a group of so-called bacteriophages. Some bacteriophages have a pronounced icosahedral head, and the tail has a spiral symmetry.
EVOLUTIONARY ORIGIN OF VIRUSES:
5 prokaryotes Characteristic features of the organization.
All known organisms are subdivided into pro- and eukaryotes. Prokaryotes include bacteria and blue-green algae; to eukaryotes - green plants, mushrooms, slime molds and animals.
Prokaryotic cells do not have a formalized nucleus, that is, the genetic material is located in the cytoplasm and is not surrounded by any membranes. Eukaryotes have a real nucleus, i.e. gene. the material is surrounded by a double membrane.
Eukaryotes and prokaryotes also differ in a number of other characteristics:
| Sign | Prokaryote | Eukaryote |
| The size | Diameter 0.5-5 microns. | Diameter up to 40 microns. The volume is 1000-10000 times greater than that of prokaryotes. |
| Forms | Unicellular, filamentous. | Unicellular, filamentous, truly multicellular. |
| Organelles | Few. None has a double membrane. | Lot. They are available with both double and single membranes. |
| Core | Not | There is |
| Nuclear shell | Not | There is |
| DNA | Closed in a ring (conventionally called a bacterial chromosome). | Nuclear DNA is a linear structure and is found in chromosomes. |
| Chromosomes | Not | There is |
| Mitosis | Not | There is |
| Meiosis | Not | There is |
| Gametes | Not | There is |
| Mitochondria | Not | There is |
| Plastids in autotrophs | Not | There is |
| Method of absorbing food | Cell membrane adsorption | Phagocytosis and pinocytosis |
| Digestive vacuoles | Not | There is |
| Flagella | There is | There is |
Prokaryotes (Latin Procaryota, from the Greek προ "before" and κάρυον "nucleus"), or prenuclear - unicellular living organisms that do not (unlike eukaryotes) have a formed cell nucleus. Prokaryotes are divided into two taxa in the rank of domain (super-kingdom): Bacteria and Archaea
Prokaryotes:
The presence of flagella, plasmids and gas vacuoles
Structures in which photosynthesis occurs - chloroplasts
The forms of reproduction are asexual, there is a pseudosexual process, as a result of which only the exchange of genetic information occurs, without increasing the number of cells.
Prokaryotic cells are characterized by the absence of a nuclear envelope; DNA is packed without the participation of histones. The type of food is osmotrophic.
The genetic material of prokaryotes is represented by one DNA molecule closed in a ring, there is only one replicon. The cells lack membrane-structured organelles.
Capable of nitrogen fixation.
Have: capsule(protects bacteria from damage, drying, it prevents bacterial phagocytosis) ; cell wall, plasmolemma, cytoplasm, ribosomes, drank(surface structures present in many bacterial cells and representing straight protein cylinders 1-1.5 μm long and 7-10 nm in diameter); flagella, nucleotide(similar to the kernel); plasmids(additional factors of heredity located in cells outside the chromosomes and representing circular (closed) or linear DNA molecules.)
6. A cell is an elementary, genetic and structural-functional biological unit. Prokaryotic and eukaryotic cells.
Cell- an elementary unit of a living system. It can be called an elementary unit because there are no smaller systems in nature, which would be inherent in all, without exception, signs (properties) of living things. It is known that organisms are unicellular (for example, bacteria, protozoa, some algae) or multicellular.
The cell has all the properties of a living system: it carries out the metabolism and energy, grows, multiplies and inherits its characteristics, reacts to external stimuli and is able to move. She is the lowest level of the organization, which has all these properties.
Specific functions in the cell are distributed between organelles, intracellular structures that have a certain shape, such as the cell nucleus, mitochondria, etc. Multicellular organisms have different cells (for example, nerve, muscle, blood cells in animals or stem cells, leaves, roots in plants ) perform different functions and therefore differ in structure. Despite the variety of shapes, cells different types have striking similarities in their main structural features.
All organisms with a cellular structure are divided into two groups: prenuclear (prokaryotes) and nuclear (eukaryotes).
The cells of prokaryotes, which include bacteria, in contrast to eukaryotes, have a relatively simple structure. In a prokaryotic cell there is no organized nucleus, it contains only one chromosome, which is not separated from the rest of the cell by a membrane, but lies directly in the cytoplasm. However, it also contains all the hereditary information of the bacterial cell.
A plant cell is characterized by the presence of various plastids, a large central vacuole, which sometimes pushes the nucleus to the periphery, as well as a cell wall located outside the plasma membrane of the cell wall, consisting of cellulose. In cages higher plants the cell center lacks a centriole, which is found only in algae. The reserve nutrient carbohydrate in plant cells is starch.
In the cells of representatives of the kingdom of fungi, the cell wall usually consists of chitin, a substance from which the outer skeleton of arthropods is built. There is a central vacuole, no plastids. Only a few fungi have a centriole in the cell center. The storage carbohydrate in fungal cells is glycogen.
In animal cells, there is no dense cell wall, no plastids. There is no central vacuole in the animal cell. The centriole is characteristic of the cell center of animal cells. Glycogen is also a reserve carbohydrate in animal cells.
7. Cell theory. History and state of the art... Its significance for biology and medicine.
The main provisions of the cell theory, its meaning
All living organisms are made up of cells - one cell (unicellular organisms) or many (multicellular). The cell is one of the main structural, functional and reproductive elements of living matter; it is an elementary living system. There are non-cellular organisms (viruses), but they can only reproduce in cells. There are organisms that have lost their cellular structure for the second time (some algae). The history of the study of the cell is associated with the names of a number of scientists. R. Hooke was the first to use a microscope to study tissues and on a cut of a cork and an elderberry core he saw cells, which he called cells. Anthony van Leeuwenhoek saw cells for the first time at 270x magnification. M. Schleiden and T. Schwann were the creators of the cell theory. They mistakenly believed that cells in the body arise from a primary non-cellular substance. Later R. Virkhov formulated one of the most important provisions of the cell theory: “Every cell comes from another cell ...” The significance of the cell theory in the development of science is great. It became obvious that the cell is the most important component of all living organisms. She is their main component morphologically; the cell is the embryonic basis of a multicellular organism, because the development of the organism begins with one cell - the zygote; the cell is the basis of physiological and biochemical processes in the body. The cell theory made it possible to come to the conclusion about the similarity of the chemical composition of all cells and once again confirmed the unity of the entire organic world.
Modern cellular theory includes the following provisions:
The cell is the basic unit of the structure and development of all living organisms, the smallest unit of living;
The cells of all unicellular and multicellular organisms are similar (homologous) in their structure, chemical composition, basic manifestations of vital activity and metabolism;
Cell reproduction occurs by dividing them, and each new cell is formed as a result of the division of the original (mother) cell;
In complex multicellular organisms, cells are specialized in their function and form tissues; organs that are closely interconnected and subordinate to the nervous and humoral systems of regulation are composed of tissues.
The significance of cell theory in the development of science consists in the fact that thanks to it it became clear that the cell is the most important component of all living organisms. It is their main "building" component, the cell is the embryonic basis of a multicellular organism, because the development of the organism begins with one cell - the zygote. The cell is the basis of physiological and biochemical processes in the body, because ultimately, all physiological and biochemical processes take place at the cellular level. The cell theory made it possible to come to the conclusion about the similarity of the chemical composition of all cells and once again confirmed the unity of the entire organic world. All living organisms are composed of cells - from one cell (protozoa) or many (multicellular). The cell is one of the main structural, functional and reproductive elements of living matter; it is an elementary living system. There are evolutionarily non-cellular organisms (viruses), but they can reproduce only in cells. Various cells differ from each other both in structure and in size (cell sizes range from 1 micron to several centimeters - these are fish and bird eggs), and in shape (they can be round like erythrocytes, tree-like like neurons), and in biochemical characteristics ( for example, in cells containing chlorofoll or bacteriochlorophyll, photosynthesis processes take place, which are impossible in the absence of these pigments), and according to functions (they distinguish between sex cells - gametes and somatic - body cells, which in turn are subdivided into many different types).
8. Hypotheses of the origin of eukaryotic cells: symbiotic, invagination, cloning. Most popular at present symbiotic hypothesis the origin of eukaryotic cells, according to which anaerobic prokaryotes, capable of only amoeboid movement, served as the basis, or host cell, in the evolution of a eukaryotic cell. The transition to aerobic respiration is associated with the presence of mitochondria in the cell, which occurred through changes in symbionts - aerobic bacteria that entered the host cell and coexisted with it.
A similar origin is suggested for flagella, whose ancestors were symbionts-bacteria that had a flagellum and resembled modern spirochetes. The acquisition of flagella by the cell had, along with the development of an active mode of movement, an important general consequence. It is assumed that the basal bodies with which the flagella are equipped could have evolved into centrioles during the onset of the mitotic mechanism.
The ability of green plants to photosynthesize is due to the presence of chloroplasts in their cells. Supporters of the symbiotic hypothesis believe that prokaryotic blue-green algae served as symbionts of the host cell, which gave rise to chloroplasts.
A strong case for symbiotic the origin of mitochondria, centrioles and chloroplasts is that the listed organelles have own DNA... At the same time, the proteins bacillin and tubulin, which make up the flagella and cilia, respectively, of modern prokaryotes and eukaryotes, have a different structure.
Central and difficult to answer is the question of the origin of the nucleus. It is believed that it could also have formed from a prokaryote symbiont. The increase in the amount of nuclear DNA, many times higher than in the modern eukaryotic cell, its amount in mitochondria or chloroplast, apparently occurred gradually by moving groups of genes from the genomes of symbionts. It cannot be ruled out, however, that the nuclear genome was formed by growing the host cell genome (without the participation of symbionts).
According to invagination hypothesis, the ancestral form of the eukaryotic cell was an aerobic prokaryote. Inside such a host cell, there were simultaneously several genomes that were initially attached to the cell membrane. Organelles with DNA, as well as a nucleus, arose by invading and detaching sections of the membrane, followed by functional specialization in the nucleus, mitochondria, and chloroplasts. In the process of further evolution, the nuclear genome became more complex, and a system of cytoplasmic membranes appeared.
Invagination hypothesis well explains the presence in the membranes of the nucleus, mitochondria, chloroplasts, two membranes. However, it cannot answer the question of why protein biosynthesis in chloroplasts and mitochondria corresponds in detail to that in modern prokaryotic cells, but differs from protein biosynthesis in the cytoplasm of a eukaryotic cell.
Cloning. In biology, a method of obtaining several identical organisms by asexual (including vegetative) reproduction. This is how, over millions of years, many species of plants and some animals reproduce in nature. However, now the term "cloning" is usually used in a narrower sense and means the copying of cells, genes, antibodies and even multicellular organisms in the laboratory. The specimens that appeared as a result of asexual reproduction are by definition genetically identical, however, they can also be observed hereditary variability caused by random mutations or created artificially by laboratory methods. The term "clone" as such comes from the Greek word "klon", which means - twig, shoot, stalk, and relates primarily to vegetative propagation. Cloning plants by cuttings, buds or tubers into agriculture has been known for thousands of years. During vegetative reproduction and cloning, genes are not distributed among the offspring, as in the case of sexual reproduction, but are preserved in their entirety. Only in animals everything happens differently. As animal cells grow, their specialization occurs, that is, the cells lose the ability to realize all genetic information embedded in the core of many generations.
9. The cell as an open system. Organization of flows of matter, energy in the cell. Specialization and integration of cells of a multicellular organism.
Cell- an open system, since its existence is possible only under conditions of constant exchange of matter and energy with the environment. The vital activity of the cell is provided by processes that form three streams: information, energy of substances.
Due to the presence of a flow of information, the cell acquires a structure that meets the criteria of a living, maintains it in time, and transmits it over a number of generations. This flow involves the nucleus, macromolecules that transfer information to the cytoplasm (mRNA), the cytoplasmic transcription apparatus (ribosomes and polysomes, tRNA, amino acid activation enzymes). Later, polypeptides synthesized on polysomes acquire tertiary and quaternary structures, and are used as catalysts or structural proteins... The genomes of mitochondria also function, and in green plants - and chloroplasts.
The flow of energy is provided by the mechanisms of energy supply - fermentation, photo - or chemosynthesis, respiration. Respiratory metabolism includes the reactions of splitting low-calorie organic "fuel" in the form of glucose, fatty acids, amino acids, the use of the released energy for the formation of high-calorie cellular "fuel" in the form of adenosine triphosphate (ATP). The energy of ATP in various processes is converted into one or another type of work - chemical (synthesis), osmotic (maintaining changes in the concentration of substances), electrical, mechanical, regulatory. Anaerobic glycolysis is a process of oxygen-free breakdown of glucose. Photosynthesis is a mechanism for converting the energy of sunlight into the energy of chemical bonds of organic substances.
10. Cell cycle, its periodization. Mitotic cycle and its mechanisms. Problems of cell proliferation in medicine.
The repeating set of events that ensure the division of eukaryotic cells is called the cell cycle. The length of the cell cycle depends on the type of dividing cells. Some cells, for example, human neurons, after reaching the stage of terminal differentiation, stop their division altogether. The cells of the lungs, kidneys, or liver in an adult organism begin to divide only in response to damage to the corresponding organs. Intestinal epithelial cells divide throughout a person's life. Even in rapidly proliferating cells, preparation for division takes about 24 hours. The cell cycle is divided into stages: Mitosis - M-phase, division of the cell nucleus. G1 phase is the period before DNA synthesis. S-phase - the period of synthesis (DNA replication). The G2 phase is the period between DNA synthesis and mitosis. Interphase - a period that includes G1, S- and G2-phases. Cytokinesis is the division of the cytoplasm. Restriction point, R-point - the time in the cell cycle when the progress of the cell towards division becomes irreversible. G0 phase - the state of cells that have reached a monolayer or lack a growth factor in the early G1 phase. Cell division (mitosis or meiosis) is preceded by chromosome doubling, which occurs during the S period of the cell cycle. The period is designated by the first letter of the word synthesis - DNA synthesis. From the end of the S period until the end of metaphase, the nucleus contains four times more DNA than the nucleus of a sperm or egg, and each chromosome consists of two identical sister chromatids.
During mitosis, chromosomes condense and at the end of prophase or the beginning of metaphase become distinguishable by optical microscopy. For cytogenetic analysis, preparations of precisely metaphase chromosomes are usually used. At the beginning of anaphase, the centromeres of homologous chromosomes are separated, and chromatids diverge to opposite poles of the mitotic spindle. After the complete sets of chromatids (from this moment they are called chromosomes) move to the poles, a nuclear envelope is formed around each of them, forming the nuclei of two daughter cells (the destruction of the nuclear envelope of the mother cell occurred at the end of prophase). Daughter cells enter the G1 period, and only in preparation for the next division do they enter the S period and DNA replication occurs in them. Cells with specialized functions that do not enter mitosis for a long time or have completely lost the ability to divide are in a state called the G0 period. Most cells in the body are diploid - that is, they have two haploid sets of chromosomes (a haploid set is the number of chromosomes in gametes, in humans it is 23 chromosomes, and a diploid set of chromosomes is 46). In the gonads, the precursors of germ cells first undergo a series of mitotic divisions, and then enter meiosis - the process of gamete formation, consisting of two successive divisions. In meiosis, homologous chromosomes mate (paternal 1st chromosome with maternal 1st chromosome, etc.), after which, during the so-called crossing-over, recombination occurs, that is, the exchange of regions between the paternal and maternal chromosomes. As a result, the genetic composition of each chromosome changes qualitatively. In the first division of meiosis, homologous chromosomes diverge (and not sister chromatids, as in mitosis), as a result of which cells with a haploid set of chromosomes are formed, each of which contains 22 doubled autosomes and one doubled sex chromosome. There is no S period between the first and second divisions of meiosis, and sister chromatids diverge into daughter cells in the second division. As a result, cells with a haploid set of chromosomes are formed, in which there is half as much DNA as in diploid somatic cells in the G1 period, and 4 times less than in somatic cells at the end of the S period. During fertilization, the number of chromosomes and DNA content in the zygote becomes as follows the same as in the somatic cell in the G1 period. The S period in the zygote paves the way for the regular division characteristic of somatic cells.
Mitosis(from the Greek mitos - thread) - division of the nucleus, following the replication of chromosomes, as a result of which the daughter nuclei contain the same number of chromosomes as the parent ones. Mitosis has a complex mechanism that includes several phases, the need for which arose in the process of evolution when cells appeared with a dramatically increased amount of DNA packed into separate chromosomes. The process of mitosis consists of: prophase, prometaphase, metaphase, anaphase and telophase.
Prophase. At the beginning of prophase, numerous cytoplasmic microtubules that make up the cytoskeleton disintegrate; in this case, a large pool of free tubulin molecules is formed. These molecules are again used to build the main component of the mitotic apparatus - the mitotic spindle. Each pair of centrioles becomes part of the mitotic center, from which microtubules radiate out like rays ("star" figure). Initially, both stars lie side by side near the nuclear membrane. In late prophase, bundles of pole microtubules interacting with each other (and visible under a light microscope as pole filaments) elongate and seem to push two mitotic centers apart from each other along the outer surface of the nucleus. In this way, a bipolar mitotic spindle is formed.
The second stage of mitosis - prometaphase begins with the rapid disintegration of the nuclear envelope into small fragments indistinguishable from fragments of the cytoplasmic reticulum. These fragments remain visible around the spindle. In mammalian cells, prometaphase takes 10-20 minutes. The mitotic spindle located near the nucleus can now penetrate into the nuclear region. In the chromosomes, on each side of the centromere, special structures are formed - kinetochores. Usually, each chromosome has one kinetochoric filament associated with each of the poles. As a result of this, two oppositely directed forces arise, which bring the chromosome into the equatorial plane. Thus, the random prometaphase movements of chromosomes and their random final orientation provide the random segregation of chromatids between daughter cells, which is so important in meiosis.
The third stage of mitosis - metaphase often lasts a long time. All chromosomes are arranged in such a way that their centromeres lie in the same plane (metaphase plate). Metaphase chromosomes are held in a deceptively static state by balanced polar forces. The kinetochore filaments are most likely responsible for the orientation of chromosomes perpendicular to the axis of the mitotic spindle and their location at an equal distance from both poles of the spindle. Probably, this arrangement of chromosomes in the metophase plate is due to the method of creating a pulling force in the mitotic spindle: this method is such that the force acting on the kinetochore filaments is weaker the closer to the pole are the kinetochores. see metaphase 1 and 2. Each chromosome is held in the metaphase plate by a pair of kinetochores and two bundles of filaments associated with them, going to opposite poles of the spindle. The metaphase ends abruptly with the separation of the two kinetochores of each chromosome.
The fourth stage of mitosis - anaphase usually lasts only a few minutes. Anaphase begins with a sudden cleavage of each chromosome, which is caused by the separation of sister chromatids at the point of their junction in the centromere. This cleavage separating the kinetochores is independent of other mitotic events and occurs even in chromosomes not attached to the mitotic spindle; it allows the polar forces of the spindle, acting on the metaphase plate, to begin the movement of each chromatid to the corresponding poles of the spindle at a rate of about 1 μm / min. During this anaphase movement, the kinetochore filaments shorten as the chromosomes approach the poles. At about the same time, the filaments of the mitotic spindle elongate and the two poles of the spindle diverge even further. Further see Mitosis: movement of chromosomes in anaphase The cellular stage in which the chromosomes diverge to the two poles of new daughter cells.
In the fifth and final stage of mitosis, telophase separated daughter chromatids approach the poles, kinetochore filaments disappear. After the elongation of the pole filaments, a new nuclear envelope is formed around each group of daughter chromatids. Condensed chromatin begins to loosen, nucleoli appear, and mitosis ends.
Proliferation. The main method of dividing tissue cells is mitosis. As the number of cells increases, cell groups or populations appear, united by a common localization within the germ layers (embryonic rudiments) and possessing similar histogenetic potencies. The cell cycle is regulated by numerous extra- and intracellular mechanisms. Extracellular influences on the cell include cytokines, growth factors, hormonal and neurogenic stimuli. The role of intracellular regulators is played by specific proteins of the cytoplasm. During each cell cycle, there are several critical points corresponding to the transition of a cell from one period of the cycle to another. If the internal control system is disturbed, the cell, under the influence of its own regulatory factors, is eliminated by apoptosis, or it is delayed for some time in one of the periods of the cycle.
Work plan:
1. The concept of biology, its relationship with other sciences ……………… ..2
14. Features of the structure of the plant cell ..................... 7
30. Penetration of nutrients into the cell. The concept of turgor, plasmolysis, plasmoplysis of microorganisms ...................... ... ... 13
45. Antibiotics and inhibitors. Routes of entry and their influence on the quality of milk. Measures to prevent their penetration into milk …………………………………………………………… 15
50. Microflora of plants and forages ……………………………… ... 18
66. Describe the causative agents of tuberculosis and brucellosis ... ..22
1. The concept of biology, its relationship with other sciences.
Science is a field of research activity aimed at obtaining new knowledge about objects and phenomena. Science includes knowledge about the subject of study, its main task is to know it more fully and deeper. The main function of science is research. The subject of the study of teaching methods in biology is the theory and practice of teaching, upbringing and development of students in this subject.
The methodology of teaching biology, like any science, learns the objective laws of the processes and phenomena that it studies. Revealing their common patterns allows her to explain and predict the course of events and act purposefully.
The main features of science, as a rule, are the goals, the subject of its study, methods of cognition and forms of expression of knowledge (in the form of fundamental scientific provisions, principles, laws, laws, theories and facts, terms). The history of the formation and development of science, the names of scientists who enriched it with their discoveries are also important.
The goals facing the methodology of teaching biology are in line with the general pedagogical goals and objectives. Therefore, this technique is a special area of pedagogy, due to the specifics of the subject of research.
The methodology of teaching biology is based on general pedagogical provisions in relation to the study of biological material. At the same time, it integrates special (natural-scientific and biological), psychological-pedagogical, ideological, cultural and other professional-pedagogical knowledge, skills and attitudes.
The methodology of teaching biology determines the goals of education, the content of the academic subject "Biology" and the principles of its selection.
The goals of education, along with the content, process and result of education, are an important element of any pedagogical system. Education takes into account both social goals and the goals of the individual. Social goals are determined by the needs of a developing society. Personal goals take into account individual abilities, interests, needs for education, self-education.
The level of education, that is, the mastery of biological knowledge, skills and abilities that contribute to active and full-fledged inclusion in educational, labor, social activities;
The level of upbringing, which characterizes the system of world outlooks, beliefs, attitude to the world around, nature, society, personality;
The level of development, which determines the ability, the need for self-development and improvement of physical and mental qualities. The goal of general secondary biological education is determined taking into account the named values and such factors as:
Integrity of the human person;
Predictiveness, that is, the orientation of the goals of biological education towards current and future biological and educational values. Thus, general secondary biological education becomes more open to renewal and adjustment;
Continuity in the system of continuing education.
The methodology of teaching biology also notes that one of the most important goals of biological education is the formation of a scientific worldview based on the integrity and unity of nature, its systemic and level structure, diversity, and the unity of man and nature. In addition, biology is focused on the formation of knowledge about the structure and functioning of biological systems, about the sustainable development of nature and society in their interaction.
The object and subject of research are the most important concepts of any science. They are philosophical categories. The object expresses the content of reality, independent of the observer.
The subjects of scientific knowledge are various aspects, properties and relations of an object, fixed in experience and included in the process of practical activity. The object of the study of the methods of teaching biology is the teaching and educational (educational) process associated with this subject. The subject of the research methodology is the goals and content of the educational process, methods, means and forms of teaching, upbringing and development of students.
In the development of science, its practical application and the assessment of achievements, a rather significant role belongs to the methods of scientific research. They are a means of knowing the subject under study and a way to achieve the goal. The leading methods of teaching biology are as follows: observation, pedagogical experiment, modeling, forecasting, testing, qualitative and quantitative analysis of pedagogical achievements. The named methods are based on experience, sensory cognition. However, empirical knowledge is not the only source of reliable knowledge. Such methods of theoretical knowledge as systematization, integration, differentiation, abstraction, idealization, system analysis, comparison, generalization help to reveal the essence of an object and a phenomenon, their internal connections.
The structure of the content of the methodology of teaching biology has been scientifically substantiated. It is divided into general and private, or special, teaching methods: natural history, in the courses "Plants. Bacteria. Mushrooms and Lichens", in the course "Animals", in the courses "Man", "General biology".
The general methodology of teaching biology considers the main issues of all biological courses: the concept of biological education, goals, objectives, principles, methods, means, forms, models of implementation, content and structures, stages, continuity, history of the formation and development of biological education in the country and the world; ideological, moral and eco-cultural education in the learning process; unity of content and teaching methods; the relationship between the forms of educational work; integrity and development of all elements of the biological education system, which ensures the strength and awareness of knowledge, skills and abilities.
Private methodologies investigate specific learning issues for each course, depending on the content of the educational material and the age of the students.
The general methodology of teaching biology is closely related to all private biological methods. Her theoretical conclusions are based on private methodological research. And they, in turn, are guided by general methodological provisions for each training course. Thus, the methodology as a science is one, the general and special parts are inextricably combined in it.
RELATIONSHIP OF BIOLOGY TEACHING METHODS WITH OTHER SCIENCES.
The methodology of teaching biology, being a pedagogical science, is inextricably linked with didactics. This is a section of pedagogy that studies the patterns of assimilation of knowledge, abilities and skills and the formation of students' beliefs. Didactics develops educational theory and teaching principles common to all subjects. The methodology of teaching biology, which has long been established as an independent area of pedagogy, develops theoretical and practical problems of the content, forms, methods and means of teaching and upbringing, due to the specifics of biology.
It should be noted that didactics, on the one hand, relies in its development on the theory and practice of methodology (not only biology, but also other academic subjects), and on the other hand, it provides general scientific approaches to research in the field of methodology, ensuring the unity of methodological principles in study of the learning process.
The methodology of teaching biology is closely related to psychology, since it is based on the age characteristics of children. The methodology emphasizes that upbringing education can be effective only if it corresponds to the age development of students.
Biology teaching methodology is closely related to biological science. The subject "Biology" is synthetic in nature. It reflects almost all the main areas of biology: botany, zoology, physiology of plants, animals and humans, cytology, genetics, ecology, evolutionary doctrine, the origin of life, anthropogenesis, etc. For the correct scientific explanation of natural phenomena, recognition of plants, fungi, animals in nature, their definition, preparation and experimentation, good theoretical and practical training is required.
The goal of biological science is to gain new knowledge about nature through research. The purpose of the subject "Biology" is to give students knowledge (facts, patterns), obtained by biological science.
Biology teaching methodology is closely related to philosophy. It contributes to the development of human self-knowledge, understanding of the place and role of scientific discoveries in the system of general development of human culture, allows you to link disparate fragments of knowledge into a single scientific picture of the world. Philosophy is the theoretical basis of the methodology, equips it with a scientific approach to the diverse aspects of training, education and development.
The connection of the methodology with philosophy is all the more important, since the study of the foundations of the science of biology about all kinds of manifestations of living matter at different levels of its organization aims at the formation and development of a materialistic worldview. The methodology of teaching biology solves this important task gradually, from course to course, with the expansion and deepening of biological knowledge, leading students to an understanding of natural phenomena, the movement and development of matter, the surrounding world.
14. Features of the structure of the plant cell.
A plant cell has a nucleus and all organelles characteristic of an animal cell: endoplasmic reticulum, ribosomes, mitochondria, Golgi apparatus. At the same time, it differs from the animal cell in the following structural features:
1) a strong cell wall of considerable thickness;
2) special organelles - plastids, in which the primary synthesis of organic substances from mineral substances occurs due to the energy of light - photosynthesis;
3) a developed system of vacuoles, largely determining the osmotic properties of cells.
A plant cell, like an animal, is surrounded by a cytoplasmic membrane, but, in addition, it is limited by a thick cell wall consisting of cellulose. The presence of a cell wall is a specific feature of plants. She determined the low mobility of plants. As a result, the nutrition and respiration of the body began to depend on the surface of the body in contact with the environment, which led in the process of evolution to a greater dismemberment of the body, much more pronounced than in animals. The cell wall has pores through which the channels of the endoplaemic network of neighboring cells communicate with each other.
The predominance of synthetic processes over the processes of energy release is one of the most characteristic features of the metabolism of plant organisms. The primary synthesis of carbohydrates from inorganic substances is carried out in plastids.
There are three types of plastids:
1) leukoplasts - colorless plastids in which starch is synthesized from monosaccharides and disaccharides (there are leukoplasts that store proteins or fats);
2) chloroplasts - green plastids containing the pigment chlorophyll, where photosynthesis is carried out - the process of formation of organic molecules from inorganic ones due to the energy of light,
3) chromoplasts, including various pigments from the group of carotenoids, which determine the bright color of flowers and fruits. Plastids can transform into each other. They contain DNA and RNA, and an increase in their number is carried out by dividing in two.
The vacuoles are surrounded by a membrane and are re-evolved from the endoplasmic reticulum. Vacuoles contain dissolved proteins, carbohydrates, low molecular weight synthesis products, vitamins, and various salts. Osmotic pressure, created by substances dissolved in the vacuolar juice, leads to the fact that water enters the cell, which causes turgor - a stressed state of the cell wall. Thick elastic walls Cytology (from cyto ... and ... logic) is the science of the cell. Studies the structure and function of cells, their connections and relationships in organs and tissues in multicellular organisms, as well as unicellular organisms. Investigating the cell as the most important structural unit of living things, cytology occupies a central position in a number of biological disciplines; it is closely related to histology, plant anatomy, physiology, genetics, biochemistry, microbiology, etc. The study of the cellular structure of organisms was begun by microscopists of the 17th century. (R. Hooke, M. Malpighi, A. Levenguk); in the 19th century. a single cell theory for the entire organic world was created (T. Schwann, 1839). In the 20th century. the rapid progress of cytology was facilitated by new methods (electron microscopy, isotope indicators, cell cultivation, etc.).
As a result of the work of many researchers, a modern cell theory was created.
The cell is the basic unit of the structure, functioning and development of all living organisms;
The cells of all unicellular and multicellular organisms are similar (homologous) in their structure, chemical composition, basic manifestations of vital activity and metabolism;
Reproduction of cells occurs by dividing them, each new cell is formed as a result of the division of the original (mother) cell;
In complex multicellular organisms, cells are specialized in their functions and form tissues; organs are composed of tissues, which are closely interconnected and subject to nervous and humoral regulation.
The cell theory is one of the most important generalizations of modern biology.
All living things on Earth, with the exception of viruses, are built of cells.
A cell is an elementary integral living system. It should be noted that the cell of an animal organism and the cell of a plant are not the same in their structure.
In a plant cell there are plastids, a shell (which gives strength and shape to the cell), vacuoles with cell sap.
Cells, despite their small size, are very complex. Research carried out over many decades has made it possible to reproduce a fairly complete picture of the structure of a cell.
The cell membrane is an ultramicroscopic film consisting of two monomolecular layers of protein and a bimolecular layer of lipids located between them.
Functions of the cell plasma membrane:
Barrier,
Communication with the environment (transport of substances),
Communication between tissue cells in multicellular organisms,
protective.
The cytoplasm is the semi-liquid medium of the cell, in which the organelles of the cell are located. The cytoplasm is composed of water and proteins. She is capable of moving at a speed of up to 7 cm / hour.
The movement of the cytoplasm within the cell is called cyclosis. Distinguish between circular and reticular cycloses.
Organelles are secreted in the cell. Organoids are permanent cellular structures, each of which performs its own function. Among them are:
Cytoplasmic matrix,
Endoplasmic reticulum,
Cell center,
Ribosomes,
Golgi apparatus,
Mitochondria,
Plastids,
Lysosomes,
1. Cytoplasmic matrix.
The cytoplasmic matrix is the main and most important part of the cell, its true internal environment.
The components of the cytoplasmic matrix carry out the processes of biosynthesis in the cell and contain the enzymes necessary for the production of energy.
2. Endoplasmic reticulum.
The entire inner zone of the cytoplasm is filled with numerous small channels and cavities, the walls of which are membranes similar in structure to the plasma membrane. These channels branch, connect to each other and form a network called the endoplasmic reticulum. ES is heterogeneous in its structure. Two types of it are known - granular and smooth.
3. Cell nucleus.
The cell nucleus is the most important part of the cell. It is found in almost all cells of multicellular organisms. The cells of organisms that contain a nucleus are called eukaryotes. The cell nucleus contains the DNA-substance of heredity, in which all the properties of the cell are encrypted.
In the structure of the nucleus, there are: the nuclear envelope, nucleoplasm, nucleolus, chromatin.
The cell nucleus performs 2 functions: storage of hereditary information and regulation of metabolism in the cell.
4. Chromosomes
The chromosome consists of two chromatids and after division of the nucleus becomes monochromatid. By the beginning of the next division, a second chromatid is completed on each chromosome. Chromosomes have a primary constriction on which the centromere is located; the constriction divides the chromosome into two arms of the same or different length.
Chromatin structures are DNA carriers. DNA consists of sections - genes that carry hereditary information and are transmitted from ancestors to descendants through germ cells. DNA and RNA are synthesized in chromosomes, which serves as a necessary factor in the transmission of hereditary information during cell division and the construction of protein molecules.
4. Cell center.
The cell center consists of two centrioles (daughter, maternal). Each has a cylindrical shape, the walls are formed by nine triplets of tubes, and in the middle there is a homogeneous substance. The centrioles are located perpendicular to each other. The function of the cell center is to participate in cell division in animals and lower plants.
5. Ribosomes
Ribosomes are ultramicroscopic organelles of a round or mushroom shape, consisting of two parts - subparticles. They do not have a membrane structure and are composed of protein and RNA. Subparticles are formed in the nucleolus. \
Ribosomes are universal organelles of all cells of animals and plants. Are in the cytoplasm in a free state or on the membranes of the endoplasmic reticulum; in addition, they are found in mitochondria and chloroplasts.
6. Mitochondria
Mitochondria are microscopic organelles with a two-membrane structure. The outer membrane is smooth, the inner one forms outgrowths of various shapes - cristae. In the matrix of mitochondria (a semi-liquid substance) there are enzymes, ribosomes, DNA, RNA. The number of mitochondria in one cell is from one to several thousand.
7. Golgi apparatus.
In the cells of plants and protozoa, the Golgi apparatus is represented by individual crescent or rod-shaped bodies. The Golgi apparatus includes: cavities bounded by membranes and located in groups (5-10 each), as well as large and small vesicles located at the ends of the cavities. All these elements make up a single complex.
Functions: 1) accumulation and transport of substances, chemical modernization,
2) the formation of lysosomes,
3) synthesis of lipids and carbohydrates on membrane walls.
8. Plastids.
Plastids are the power plants of the plant cell. They can transform from one species to another. There are several types of plastids: chloroplasts, chromoplasts, leukoplasts.
9. Lysosomes.
Lysosomes are microscopic single-membrane organelles of a round shape. Their number depends on the vital activity of the cell and its physiological state. The lysosome is a digestive vacuole that contains dissolving enzymes. In the case of starvation, the cells are digested some organelles.
In the event of destruction of the lysosome membrane, the cell digests itself.
The nutrition of the animal and plant cells occurs in different ways.
Large molecules of proteins and polysaccharides enter the cell by phagocytosis (from the Greek phagos - devouring and kitos - vessel, cell), and liquid drops - by pinocytosis (from the Greek pinot - I drink and kitos).
Phagocytosis is a way of feeding animal cells, in which nutrients enter the cell.
Pinocytosis is a universal method of nutrition (for both animals and plant cells), in which dissolved nutrients enter the cell.
A microscopic cell contains several thousand substances that are involved in a variety of chemical reactions. Chemical processes in a cell are one of the basic conditions for its life, development and functioning. All cells of animals and plant organisms, as well as microorganisms, are similar in chemical composition, which indicates the unity of the organic world.
Out of 109 elements of Mendeleev's periodic system, a significant majority of them are found in cells. The cell contains both macronutrients and microelements.
In conclusion, we will draw the main conclusions:
The cell is an elementary unit of life, the basis of the structure, life, reproduction and individual development of all organisms. There is no life outside the cell (except for viruses).
Most of the cells are arranged in the same way: they are covered with an outer membrane - the cell membrane and filled with a liquid - the cytoplasm. The cytoplasm contains a variety of structures - organelles (nucleus, mitochondria, lysosomes, etc.), which carry out various processes.
The cell comes only from the cell.
Each cell performs its own function and interacts with other cells, ensuring the vital activity of the body.
There are no special elements in the cell that are characteristic only of living nature. This indicates the connection and unity of animate and inanimate nature.
30. Penetration of nutrients into the cell. The concept of turgor, plasmolysis, plasmoptosis of microorganisms.
Power mechanism. The entry of nutrients into a bacterial cell is a complex physicochemical process, which is facilitated by a number of factors: the difference in the concentration of substances, the size of molecules, their solubility in water or lipids, the pH of the medium, the permeability of cell membranes, etc. the cell is distinguished by four possible mechanisms.
The simplest method is passive diffusion, in which the entry of a substance into the cell occurs due to the difference in the concentration gradient (the difference in concentration on both sides of the cytoplasmic membrane). The size of the molecule is of decisive importance. Obviously, there are areas in the membrane through which small-sized substances can penetrate. One of these compounds is water.
Most of the nutrients enter the bacterial cell against the concentration gradient, therefore enzymes must be involved in this process and energy can be expended. One of these mechanisms is facilitated diffusion, which occurs when the concentration of the substance is higher outside the cell than inside. Facilitated diffusion is a specific process and is carried out by special membrane proteins, carriers, called permease, since they perform the function of enzymes and have specificity. They bind a molecule of a substance, transfer it unchanged to the inner surface of the cytoplasmic membrane and release it into the cytoplasm. Since the movement of a substance occurs from a higher concentration to a lower one, this process takes place without energy consumption.
The third possible mechanism of transport of substances has taken the name of active transport. This press is observed at low substrate concentrations in the environment and the transport of solutes is also carried out unchanged against the concentration gradient. Permeases are involved in the active transfer of substances. Since the concentration of a substance in a cell can be several thousand times higher than in the external environment, active transfer is necessarily accompanied by the expenditure of energy. Adenosine tri-phosphate (ATP), accumulated by the bacterial cell during redox processes, is consumed.
And, finally, with the fourth possible mechanism of nutrient transfer, radical translocation is observed - the active transfer of chemically altered molecules, which in general are not able to pass through the membrane. Permeases are involved in the transfer of radicals.
The release of substances from the bacterial cell occurs either in the form of passive diffusion (for example, water), or in the process of facilitated diffusion with the participation of permeases.
Organic matter is needed to feed soil microorganisms. There are two ways for organic matter to enter the soil - root exudates of plants with post-harvest residues and the introduction of organic matter into the soil from the outside, in the form of compost, manure, green manure, etc.
Turgor(from late lat. turgor swelling, filling), internal hydrostatic pressure in a living cell, causing tension in the cell membrane. In animals, the turgor of the cells is usually low, in plant cells, the turgor pressure maintains the leaves and stems (in herbaceous plants) in an upright position, gives the plants strength and stability. Turgor is an indicator of water content and the state of the water regime of plants. A decrease in turgor is accompanied by the processes of autolysis, wilting and aging of cells.
If the cell is in a hypertonic solution, the concentration of which is greater than the concentration of the cell sap, then the rate of diffusion of water from the cell sap will exceed the rate of diffusion of water into the cell from the surrounding solution. Due to the release of water from the cell, the volume of cell juice is reduced, turgor decreases. A decrease in the volume of the cellular vacuole is accompanied by the separation of the cytoplasm from the membrane - plasmolysis occurs.
Plasmolysis(from the Greek plasmas molded, shaped and ... lys), in biology, the separation of the protoplast from the shell under the action of a hypertonic solution on the cell. Plasmolysis is characteristic mainly of plant cells with a strong cellulose membrane. Animal cells in a hypertonic solution shrink.
Plasmoptiz(plasma - + Greek ptisis crushing) - swelling of microbial
cells and destruction of their membranes in a hypotonic solution.
45. Antibiotics and inhibitors. Routes of entry and their influence on the quality of milk. Measures to prevent them from entering milk.
Antibiotics are a waste product of various microorganisms. Antibiotics have an inhibitory effect on the reproduction of other microbes and therefore are used to treat various infectious diseases. A group of antibiotics that block the synthesis of nucleic acids (DNA and RNA) is used as immunosuppressants, since in parallel with the suppression of bacterial reproduction, it inhibits the proliferation (reproduction) of cells of the immune system. Representatives of this group of drugs are Actinomycin
Particular attention should be paid to measures to prevent the ingress of antibiotics into animal products. Antibiotics can get into milk during the treatment of animals, as well as when feeding concentrated and other feed intended for pigs or biological industry waste containing mycelium and other antibiotics to lactating cows. Apparently, the possibility of deliberate addition of antibiotics to milk in order to reduce bacterial contamination of collected milk cannot be absolutely ruled out.
Several methods are used to detect inhibitory substances in milk. The simplest, most affordable and less laborious is biological. The essence of the method is to suppress the growth of lactic acid streptococcus sensitive to inhibiting substances, for example Str. thermo-philus added to the test milk sample containing an inhibiting substance. The result of the reaction is recorded by the color of the milk column into which the indicator is added. The initial color indicates a positive reaction, i.e., the presence of an inhibiting substance. However, milk contains in its composition the so-called natural inhibiting substances, such as lactoferrin, properdin, lysozymes and many others, which also inhibit the growth of lactic acid bacteria and in particular Str. thermophilus. Therefore, although it is assumed that most natural inhibitory substances should be destroyed when the sample is heated for 10 min at 85 ° C, the biological method is not specific and additional studies are required to establish the type of added chemical or antibiotic. For this reason, until now, there is not a single biological method by which it would be possible to identify inhibitory substances in
The problem of milk contamination with inhibitory substances, including antibiotics, is becoming more and more important every year.
Inhibitory substances include antibiotics, sulfonamides, nitrofurans, nitrates, preservatives (formalin, hydrogen peroxide), neutralizing (soda, sodium hydroxide, ammonia), detergents and disinfectants, etc.
The presence of antibiotic residues is a particular danger to humans and a serious problem for the dairy industry, as they can disrupt the production process by inhibiting the starter microflora. This leads to serious financial losses. But the most dangerous are the consequences of the ingestion of antibiotic residues in the human body.
Pesticides used to protect plants from pests are also dangerous to human and animal health. Milk containing residual amounts is not accepted for processing. Pesticides differ in their specific action. Chlorine insecticides are persistent and lipolytic and are therefore particularly hazardous in food. Organic phosphoric acid esters and carbamates do not accumulate in food and are not of interest for milk hygiene. Herbicides and fungicides are generally not very resistant. Their residues in milk have not yet been found, therefore, it is impractical to determine their content.
The manifestation of the inhibitory properties of milk is influenced by a variety of factors. Possible sources of inhibitors getting into milk are: violations in milk rejection in the treatment of animals; sanitization of milking and dairy equipment; the use of low-quality feed; the ingress of a number of chemicals into the feed.
The inhibitory properties of milk can be influenced by the feeding of the cows and the quality of the feed. The dosage of chemical reagents should be strictly observed when preserving silage. The inhibitory properties of milk can be influenced by the presence of an increased content of nitrates or nitrites in feed.
In order to prevent the ingress of residual amounts of detergents, detergents, disinfectants and disinfectants into milk and their possible influence on the results of the determination of inhibiting substances, the sanitary treatment of milking and dairy equipment must be carried out strictly in accordance with sanitary rules. In case of positive reactions to the presence of residual amounts of sanitary products on the surface of milking and dairy equipment
it is necessary to rinse it again with water.
One of the ways that antibiotics and other drugs get into milk is through intramuscular injection. Antibiotics and sulfonamides are most commonly seen when cows are being treated for mastitis.
Taking into account the specificity of the effect of various inhibiting substances both on the health of humans and animals, and on the technological properties of milk, the solution to the problem under consideration largely depends on the development and implementation of highly effective, highly specific methods of its control for the presence of inhibiting substances. It is not enough to establish their presence, it is important to determine not only the type, but also the specific substance that caused the manifestation of the inhibitory properties of milk. This allows you to analyze the situation in order to find out the possible source of this substance getting into it.
Currently, the country has GOST standards on methods for the determination of inhibiting substances in milk. In particular, at dairy enterprises it is possible to determine the presence of soda, ammonia, hydrogen peroxide in it.
Another important condition for ensuring the safety of milk, including its inhibitory properties, is quality control exclusively in independent testing laboratories. In this regard, there is a need to create a state regulatory framework, including a system of payments for raw milk between rural producers and purchasing factories based on measurements of milk quality by such laboratories.
50. Microflora of plants and feed.
Epiphytic microflora.
A varied microflora, called epiphytic, is constantly present on the surface parts of plants. On stems, leaves, flowers, fruits, the following non-spore types of microorganisms are most often found: Bact, herbicola makes up 40% of all epiphytic microflora, Ps. fluorescens - 40%, lactic acid bacteria - 10%, the like - 2%, yeast, mold fungi, cellulose, butyric acid, thermophilic bacteria -
After mowing and loss of plant resistance, as well as due to mechanical damage to their tissues, epiphytic and, first of all, putrefactive microflora, multiplying intensively, penetrates into the thickness of plant tissues and causes their decomposition. That is why crop production (grain, coarse and succulent fodder) is protected from the destructive effect of epiphytic microflora by various conservation methods.
It is known that plants have bound water, which is part of their chemical substances, and free water, which is drip-liquid. Microorganisms can multiply in the plant mass only if there is free water in it. One of the most common and affordable methods for removing free water from crop products and therefore preserving them is drying and ensiling.
Drying grain and hay provides for the removal of free water from them. Therefore, microorganisms cannot multiply on them as long as these products are dry.
Freshly cut, unstable grass contains 70 - 80% water, dried hay only 12-16%, the remaining moisture is bound to organic substances and microorganisms and is not used. During the drying of hay, about 10% of organic matter is lost, mainly during the decomposition of proteins and sugars. Especially large losses of nutrients, vitamins and mineral compounds occur in dried hay in swaths (windrows) when it rains frequently. Distilled rain water washes them up to 50%. Significant losses of dry matter occur in the grain during its self-heating. This process is due to thermogenesis, that is, the creation of heat by microorganisms. It arises because thermophilic bacteria use for their life only 5-10% of the energy of the nutrients they consume, and the rest is released into their environment - grain, hay.
Silage of fodder. When growing forage crops (corn, sorghum, etc.) from one hectare, it is possible to obtain significantly more feed units in green mass than in grain. In terms of starch equivalent, the nutritional value of green mass during drying can be reduced to 50%, and during ensiling only up to 20%. When ensiling, small leaves of plants with a high nutritional value are not lost, and when dried, they fall off. Silage can also be placed in variable weather. Good silage is a succulent, vitamin, milk-producing forage.
The essence of ensiling is that lactic acid microbes that decompose sugars with the formation of lactic acid, accumulating up to 1.5-2.5% of the silage weight, intensively multiply in the crushed green mass in the container. At the same time, acetic acid bacteria multiply, converting alcohol and other carbohydrates into acetic acid; it accumulates 0.4-0.6% by weight of the silage. Lactic and acetic acids are a strong poison for putrefactive microbes, so their reproduction stops.
Silage remains in good condition for up to three years, as long as it contains at least 2% lactic and acetic acids, and the pH is 4-4.2. If the reproduction of lactic acid and acetic bacteria weakens, then the concentration of acids decreases. At this time, yeast, molds, butyric acid and putrefactive bacteria begin to multiply at the same time, and the silage deteriorates. Thus, obtaining good silage depends primarily on the presence of sucrose in the green mass and the intensity of the development of lactic acid bacteria.
In the process of silage maturation, three microbiological phases are distinguished, characterized by a specific species composition of microflora.
The first phase is characterized by the multiplication of mixed microflora with some predominance of putrefactive aerobic non-spore bacteria - Escherichia coli, Pseudomonas, lactic acid microbes, yeast. Spore-bearing putrefactive and butyric acid bacteria multiply slowly and do not prevail over lactic acid bacteria. The main medium for the development of mixed microflora at this stage is plant sap, which is released from plant tissues and fills the space between the crushed plant mass. This contributes to the creation of anaerobic conditions in the silage, which inhibits the development of putrefactive bacteria and favors the reproduction of lactic acid microbes. The first phase with dense storage of silage, that is, under anaerobic conditions, lasts only 1-3 days, with loose storage under aerobic conditions, it is longer and lasts 1-2 weeks. During this time, the silage is heated by intensive aerobic microbiological processes. The second phase of silage maturation is characterized by rapid multiplication of lactic acid microbes, and at first, predominantly coccal forms develop, which are then replaced by lactic acid bacteria.
Due to the accumulation of lactic acid, the development of all putrefactive and butyric acid microorganisms stops, while their vegetative forms die, only spore-bearing ones remain (in the form of spores). With full observance of the technology of silage in this phase, homofermentative lactic acid bacteria multiply, forming only lactic acid from sugars. In case of violation of the technology of silage filling, when in it. contains air, the microflora of heteroenzymatic fermentation develops, resulting in the formation of unwanted volatile acids - butyric, acetic, etc. The duration of the second phase is from two weeks to three months.
The third phase is characterized by the gradual death of lactic acid microbes in the silage due to the high concentration of lactic acid (2.5%). At this time, the ripening of the silage is completed, a conditional indicator of its suitability for feeding is the acidity of the silage mass, which decreases to pH 4.2 - 4.5 (Fig. 37). Under aerobic conditions, mold and yeast begin to multiply, which break down lactic acid, butyric acid and putrefactive bacteria germinating from the spores use this, as a result the silage becomes moldy and rotten.
Silage defects of microbial origin. Failure to comply with the proper conditions for laying and storing the silage will cause certain defects.
Decay of silage, accompanied by significant self-heating, is noted when it is loosely laid and insufficiently compacted. The rapid development of putrefactive and thermophilic microbes is facilitated by the air in the silo. As a result of protein decomposition, silage acquires a putrid, ammonia-like odor and becomes unusable.
acquires a putrid, ammoniacal odor and to feeding. Decay of silage occurs in the first microbiological phase, when the development of lactic acid microbes and the accumulation of lactic acid, suppressing putrefactive bacteria, are delayed. To stop the development of the latter, it is necessary to lower the pH in the silage to 4.2-4.5. The rotting of the silage is caused by Er. herbicola, E. coli, Ps. aerogenes. P. vulgaris, B. subtilis, Ps. fluorescens as well as molds.
Rancidity of silage is caused by the accumulation of butyric acid in it, which has a sharp bitter taste and an unpleasant odor. In a good silage, butyric acid is absent, in a silage of average quality it is found up to 0.2%, and in an unsuitable for feeding - up to 1%.
The causative agents of butyric acid fermentation are capable of converting lactic acid into butyric acid, as well as causing putrefactive decomposition of proteins, which aggravates their negative effect on the quality of silage. Butteric acid fermentation is manifested with the slow development of lactic acid bacteria and insufficient accumulation of lactic acid, at a pH above 4.7. With the rapid accumulation of lactic acid in the silage up to 2% and pH 4-4.2, butyric acid fermentation does not occur.
The main causative agents of butyric acid fermentation in silage: Ps. fluo-rescens, Cl. pasteurianum, Cl. felsineum.
Peroxidation of silage is observed during vigorous reproduction of acetic acid, as well as putrefactive bacteria capable of producing acetic acid. Acetic acid bacteria multiply especially intensively in the presence of ethyl alcohol in the silage, accumulated by alcoholic fermentation yeast. Yeast and acetic acid bacteria are aerobes; therefore, a significant content of acetic acid in the silage and, consequently, its peroxidation is noted in the presence of air in the silo.
Silage mold occurs when there is air in the silo, which favors the intensive development of mold and yeast. These microorganisms are always found on plants, therefore, under favorable conditions, their rapid reproduction begins.
Rhizosphere and epiphytic microflora can play a negative role as well. Root crops are often affected by rot (black - Alternaria radicina, gray - Botrutus cinirea, potato - Phitophtora infenstans). Excessive activity of butyric acid fermentation pathogens leads to spoilage of silage. On vegetative plants, ergot (claviceps purpurae) reproduce, causing the disease ergotism. Mushrooms cause toxicosis. The causative agent of botulism (Cl. Votulinum), getting into the feed with soil and feces, causes severe toxicosis, often fatal. Many fungi (Aspergillus, Penicillum, Mucor, Fusarium, Stachybotrus) colonize food, multiplying under favorable conditions, and cause acute or chronic toxicosis in animals, often accompanied by nonspecific symptoms.
Microbiological preparations are used in the diets of animals and birds. Enzymes improve the absorption of feed. Vitamins and amino acids are obtained on a microbiological basis. Use of bacterial protein is possible. Fodder yeast is a good protein and vitamin feed. Yeast contains an easily digestible protein, provitamin D (zgosterol), as well as vitamins A, B, E. Yeast multiplies very quickly, therefore, in industrial conditions, it is possible to obtain a large amount of yeast mass when cultivated on molasses or saccharified fiber. At present, in our country, dry feed yeast is prepared in large quantities. For their manufacture, a culture of feed yeast is used.
66. Describe the causative agents of tuberculosis and brucellosis.
Brucellosis – a disease that affects not only cattle, but also pigs, rats and other animals. The causative agents are bacteria of the genus Brucella. These are small, immobile coccoid bacteria, gram-negative, do not form spores, aerobes. Contain endotoxin. The extreme limits of growth are 6-45 0 C, the temperature optimum is 37 0 C. When heated to 60-65 0 C, these bacteria die in 20-30 minutes, while boiling - after a few seconds. Brucella is characterized by high viability: in dairy products (feta cheese, cheese, butter) they are stored for several months. The incubation period is 1-3 weeks or more. Milk from the foci of this infection is pasteurized at elevated temperatures (at 70 0 C for 30 minutes), boiled for 5 minutes or sterilized.
Brucellosis - a chronic disease of animals. It is detected in milk by a ring test based on the detection of the corresponding antibodies. On farms, unfavorable for brucellosis, it is prohibited to export milk from a healthy herd in a non-disinfected
Such milk is pasteurized and either exported to the dairy or used inside the farm. Milk from cows that respond positively to
brucellosis, boiled and used for on-farm needs.
Tuberculosis – cause mycobacteria of the genus Mycobacterium, related to actinomycetes. The shape of the cells is variable: rods are straight, branched and curved. Aerobes, immobile, do not form spores, but due to the high content of mycolic acid and lipids, they are resistant to acids, alkalis, alcohol, drying, and heating. They are stored in dairy products for a long time (in cheese - 2 months, in butter - up to 3 months). Sensitive to sunlight, ultraviolet rays, high temperatures: at 70 0 С they die after 10 minutes, at 100 0 С - after 10 seconds. Tuberculosis differs from other infections by a long incubation period - from several weeks to several years. In order to prevent this infection, it is not allowed to use milk from sick animals for food.
Tuberculosis - a chronic disease of animals. Standing out with milk
mycobacterium tuberculosis, which have a wax coating, are able to co-
stored in the external environment. Milk from a tuberculosis-dysfunctional farm is pasteurized directly on the farm at a temperature of 85 ° C for 30 minutes.
or at a temperature of 90 ° C for 5 minutes. Disinfected in this way
bom milk, obtained from animals of healthy groups, sending
goes to the dairy, where it is re-pasteurized and taken as a second
variety. Milk from animals that respond positively to tuberculin,
disinfected by boiling, after which they are used for fattening young
nyaka. Milk obtained from animals with clinical signs of tu-
berculosis, are used in the diet of fattening animals after 10
boiling for a minute. Milk is destroyed with udder tuberculosis.
It is a science that deals with the study of the size, shape and structure of animals, plants and microorganisms, as well as the ratio and arrangement of the parts of which they are made.
What is morphology in biology: definition
Typically, morphology contrasts with physiology, which studies the functions of organisms and their parts. Functions and structures are so closely related that their separation is somewhat arbitrary. What is morphology in biology? The area of her study was originally associated with the bones, muscles, blood vessels of living organisms, as well as with the roots, stems, leaves and flowers of higher plants. However, the advent of the light microscope made it possible to study some of the structural details of individual tissues and cells.
Thanks to the methods of obtaining ultrathin sections, a completely new aspect of morphology has been created - the composition of the structure of cells. Electron microscopy reveals the amazing complexity of the composition of plants and animals. Thus, morphology is a science that includes the study of biological structures in a huge range of sizes, from macroscopic to molecular. A thorough knowledge of this branch of biology is of fundamental importance for the doctor, veterinarian, pathologist, all those who are related to the types and causes of structural changes that arise as a result of specific diseases.
Modern morphology
One of the main directions of modern morphology is the elucidation of the molecular basis of the cellular structure. A method such as electron microscopy played an important role in this. Complex details of the cellular structure were identified, which served as the basis for correlating biological organelles with specific cell functions.
As for plants, there were discovered Interesting Facts about such important structures as chloroplasts, which contain chlorophyll, without which the process of photosynthesis would be impossible. The structural details of bacteria and blue-green algae, which are similar to each other in many respects but differ markedly from higher plants and animals, have also been studied for more high level in order to determine their origin.
Morphology and taxonomy
What does morphology mean in biology and how is it related to other biological disciplines? It is of great importance in taxonomy. The morphological features characteristic of a particular species are used to identify it. An example would be traits that distinguish closely related plant and animal species, such as body color, size, and proportions. Thus, morphological features can be very useful in classifying living organisms. The connection with anatomy, embryology and physiology is also clearly visible.
Aspects of morphology
The most famous aspect of morphology is the study of the general structure, organs, and the organism as a whole. A thorough study of the adaptation process made it possible to conclude that sequential adaptation to changing conditions is directly related to the evolutionary history of various animals. The next aspect is changes in genes (mutations), which occur constantly and can lead to a decrease in the size and change in the function of the organ. On the other hand, changes in the environment or lifestyle of a species may make an organ unnecessary altogether.
An important section of biology
What is morphology in biology? This is the section dealing with the study of the shape and external structures of organisms.
Among the main methods are observation, description and analysis of data on various species, while assessing the importance and significance of form variations within a species for taxonomic studies, as well as the study of speciation and adaptation.
The term "biology" was introduced by JB Lamarck and Treviranus in 1802.
Biology is a system of sciences, the objects of study of which are living beings and their interaction with the environment. Biology studies all aspects of life, in particular the structure, functioning, growth, origin, evolution and distribution of living organisms on Earth. Classifies and describes living things, the origin of their species, interaction with each other and with the environment.
At the heart of modern biology are five fundamental principles: cell theory, evolution, genetics, homeostasis, and energy.
In biology, the following levels of organization are distinguished:
1. Cellular, subcellular and molecular level: Cells contain intracellular structures that are built from molecules.
2. Organic and organ-tissue level: in multicellular organisms, cells are tissues and organs. The organs, in turn, interact within the whole organism.
3. Population level: individuals of the same species living on a part of the range form a population.
4. Species level: individuals freely crossing with each other possessing morphological, physiological, biochemical similarities and occupying a certain area (distribution area) form a biological species.
5. Biogeocenotic and biosphere level: biogeocenoses are formed on a homogeneous area of the earth's surface, which, in turn, form the biosphere.
Most of the biological sciences are disciplines with a narrower specialization. Traditionally, they are grouped according to the types of organisms studied: botany studies plants, zoology - animals, microbiology - unicellular microorganisms. Areas within biology are further divided either by the scope of research or by the methods used: biochemistry studies the chemical foundations of life, molecular biology - complex interactions between biological molecules, cell biology and cytology - the main building blocks of multicellular organisms, cells, histology and anatomy - the structure of tissues and organism from individual organs and tissues, physiology - the physical and chemical functions of organs and tissues, ethology - the behavior of living things, ecology - the interdependence of various organisms and their environment.
The transmission of hereditary information is studied by genetics. The development of an organism in ontogenesis is studied by developmental biology. Origin and historical development wildlife - paleobiology and evolutionary biology.
On the borders with related sciences, there are: biomedicine, biophysics (the study of living objects physical methods), biometrics, etc. In connection with the practical needs of man, such areas as space biology, sociobiology, labor physiology, and bionics arise.
Biology is closely related to other sciences and sometimes it is very difficult to draw a line between them. The study of the vital activity of a cell includes the study of molecular processes occurring inside a cell, this section is called molecular biology and sometimes refers to chemistry and not to biology. Chemical reactions occurring in the body are studied by biochemistry, a science that is much closer to chemistry than to biology. Many aspects of the physical functioning of living organisms are studied by biophysics, which is very closely related to physics. Sometimes ecology is singled out as an independent science - the science of the interaction of living organisms with the environment (living and inanimate nature). The science that studies the health of living organisms has long stood out as a separate area of knowledge. This area includes veterinary medicine and a very important applied science - medicine, which is responsible for human health.
Biology will help students to understand the essence of life processes and correctly assess the possibilities of the therapeutic effect of medicinal substances on the human body.
The subject "Biology" in pharmaceutical universities (faculties), together with other disciplines, is ultimately called upon to form a specialist capable of solving general biological, medical and pharmaceutical problems related to the problem of "Man and Medicines".
1. To be able to interpret universal biological phenomena, the basic properties of living things (heredity, variability, irritability, metabolism, etc.) as applied to humans.
2. To know evolutionary connections (phylogeny of organs, occurrence of malformations).
3. Analyze the patterns and mechanisms of normal ontogenesis and interpret them in relation to humans.
4. Master the basics of human biomedical research.
New biology - a part of science that is not included in conventional biology and medicine. New biology is based on quantum physics by giving meaning to invisible sexes and energies such as mind. Here are the differences between new and traditional science... Traditional science is based on Newtonian physics and claims that ours is just a car, like a car, it says that the car is controlled by a built-in computer, and we are just passengers who are transported by this car. New Science Says The Mind Is The Driver And The Traditional Driver Doesn't and this is the main difference between the two approaches. The new biology teaches that a person controls his own car, and this is what people need to be taught. This is an important part of the new science.
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