Biology(from Greek. bios– life + logos- word, doctrine) - a science that studies life as a phenomenon that occupies a special place in the universe. Together with other sciences that study nature (physics, chemistry, astronomy, geology, etc.), it is among the natural sciences. Usually, the humanities are also distinguished into an independent group (studying the laws of existence and development of a person, human society); these include sociology, psychology, anthropology, ethnography, etc.
The phenomenon of man (as a biosocial being) is of interest to both natural and human sciences. But biology plays a special role, being a link between them. This conclusion is based on modern ideas about the development of nature, which led to the emergence of life. In the process of the evolution of living organisms, a person arose with qualitatively new properties - reason, speech, the ability for creative activity, a social way of life, etc.
The existence and development of inanimate nature is subject to physical and chemical laws. With the advent of living organisms, they begin to carry out biological processes having a fundamentally different character and subject to other laws - biological. However, it is important to note that, along with this, the physicochemical processes that underlie the arising (qualitatively different and peculiar) biological phenomena are preserved.
The specific qualities and social properties of a person do not exclude his natural belonging. In the human body, both physicochemical and biological processes are carried out (as in all living beings). However, an individual can fully develop only in society, in communication with other people. Only in this way speech is mastered and knowledge, skills and abilities are acquired. The fundamental difference here is that the existence and development of mankind is based on its ability to know, to accumulate knowledge from generation to generation, to productive activity.
Truly grandiose achievements of science, including biology, in the 20th century. significantly expanded and deepened our understanding of both the unity of nature and man, and their complex relationships. For example, environmental data have shown that living organisms, including humans, are not only dependent on nature, but also act as a powerful factor influencing both nature and even space. This applies, in particular, to the Earth's atmosphere, the formation of vast geological layers, the formation of island systems, etc. Mankind currently has the strongest impact on the animate and inanimate nature of the planet.
Biology today is a complex of sciences that studies a variety of living beings, their structure and functioning, distribution, origin and development, as well as natural communities of organisms, their relationship with each other, with inanimate nature and man.
In addition to its general cognitive significance, biology plays a huge role for a person, having long served as the theoretical basis of medicine, veterinary medicine, agronomy, and animal husbandry.
Now there are branches of production that are based on biotechnology, i.e., they use living organisms in the production process. We can mention the food, pharmaceutical, chemical industries, etc.
Various biological sciences are also of great importance in connection with the problem of the relationship between man and nature. Only on a scientific basis is it possible to solve such problems as the rational use of natural resources, a sparing attitude towards the world around us, and a competent organization of environmental protection activities.
"General Biology" is a subject that represents the most important stage in the biological education of secondary school students. It relies on the knowledge, skills and abilities that have already been acquired in the study of botany, zoology, and human biology.
Starting from the 6th grade, you got acquainted with different groups of living organisms: viruses, bacteria, fungi, plants, animals. You learned about their structure and functioning, variety of forms, distribution, etc. In the 8th grade, the subject of biology classes was a person and his specificity as a biosocial being.
General biology, unlike other specialized disciplines, considers what the name itself says, general(for all living organisms) the peculiar properties and qualities of everything alive general patterns of organization, life, development, inherent in all forms life.
Chapter 1 The Essence of Life
§ 1. Definition of life and fundamental properties of the living
One of the challenges facing any science is the need to create definitions, i.e. e. brief statements, giving, however, complete representation of the essence of an object or phenomenon. In biology, there are dozens of options for defining life, but none of them satisfies the two requirements mentioned above at once. Either the definition occupies 2-3 pages of the book, or some important characteristics of the living are “dropped out” of it.
Life in its specific manifestations on Earth is represented by diverse forms of organisms. According to modern biological knowledge, it is possible to single out a set of properties that should be recognized as common to all living beings and which distinguish them from the bodies of inanimate nature. Thus, to the concept a life we will come by comprehending the specific properties of living organisms.
The specificity of the chemical composition. The difference between living and non-living is clearly manifested already at the level of their chemical composition. Very often you can find the phrase "organic nature" as a synonym for "wildlife". And this is absolutely fair. Everything organic substances are created in living organisms in the course of their vital activity. As the experts say, they biogenic(i.e. created by living beings). Moreover, it is organic substances that determine the possibility of the existence of living organisms themselves. So, for example, nucleic acids contain hereditary (genetic) information; proteins determine the structure, provide movement, regulation of all life processes; sugars (carbohydrates) perform energy functions, etc. Not a single living being is known on Earth that would not be a combination of proteins and nucleic acids.
Organic substances have more complex molecules than inorganic ones and are characterized by an infinite variety, which, as we shall see below, largely determines the diversity of living organisms.
Structural organization of living beings. Even in elementary grades, in the lessons of botany and zoology, you were told that the scientists T. Schwann and M. Schleiden (1839) formulated the cellular theory of the structure of all plants and animals. Cage has since been recognized structural and functional unit any living beings. This means that their bodies are built of cells (there are also single-celled ones) and the implementation of the body's vital activity is determined by the processes occurring inside the cells themselves. Remember also that the cells of all plants and animals are similar in structure (have membrane, cytoplasm, nucleus, organelles).
But already at this level it appears structural complexity organization of the living. There are many different components (organelles) in the cell. Such a heterogeneity of its internal composition makes it possible to simultaneously carry out hundreds and thousands of chemical reactions in such a small space.
The same is true for multicellular organisms. From a variety of cells, various tissues, organs, organ systems (performing different functions) are formed, which together make up a complex and heterogeneous integral system - a living organism.
metabolism in living organisms. All living organisms have an inherent exchange of matter and energy with the environment.
F. Engels at the end of the 19th century. singled out this property of the living, deeply appreciating its significance. Offering his definition of life, he wrote:
Life is a mode of existence of protein bodies, the essential point of which is the constant exchange of substances with the external nature surrounding them, and with the cessation of this metabolism, life also ceases, which leads to the decomposition of the protein.
Inorganic bodies can also have metabolism... But the difference is that in the case of inorganic bodies, metabolism destroys them, while in the case of organic bodies it is a necessary condition for their existence.
In this process, a living organism receives the substances it needs as a material for growth, restoration of destroyed (“used out”) components and as a source of energy for life support. The resulting substances harmful or unnecessary to the body (carbon dioxide, urea, water, etc.) are excreted into the external environment.
Self-reproduction (reproduction) of organisms. reproduction- reproduction of one's own kind - the most important condition for the continuation of life. An individual organism is mortal, its life span is limited, and reproduction ensures the continuity of the existence of species, more than compensating for the natural death of individuals.
Heredity and variability.
Heredity- the ability of organisms to transmit from generation to generation the entire set of characteristics that ensure the adaptability of organisms to their environment.
It provides similarity, similarity of organisms of different generations. It is no coincidence that the synonym for reproduction is the word self-reproduction. Individuals of one generation give rise to individuals of a new generation, similar to themselves. Today, the mechanism of heredity is well known. Hereditary information (i.e. information about the characteristics, properties and qualities of organisms) is encrypted in nucleic acids and is transmitted from generation to generation in the process of reproduction of organisms.
Obviously, with "hard" heredity (ie, absolute repetition of parental traits) against the background of changing environmental conditions, the survival of organisms would be impossible. Organisms could not develop new habitats. Finally, the evolutionary process, the formation of new species, would also be excluded. However, living organisms also have variability,which is understood as their ability to acquire new features and lose the old ones. The result is a variety of individuals belonging to the same species. Variability can occur both in individual individuals during their individual development, and in a group of organisms in a series of generations during reproduction.
Individual (ontogeny) and historical (evolutionary; phylogenesis) development of organisms. Any organism during its life (from the moment of its inception to natural death) undergoes regular changes, which are called individual development. There is an increase in the size and weight of the body - growth, the formation of new structures (sometimes accompanied by the destruction of previously existing ones - for example, the loss of a tail by a tadpole and the formation of paired limbs), reproduction, and, finally, the end of existence.
The evolution of organisms is an irreversible process of the historical development of living things, during which a successive change of species is observed as a result of the disappearance of previously existing ones and the emergence of new ones. By its nature, evolution is progressive, since the organization (structure, functioning) of living beings has passed through a number of stages - pre-cellular life forms, unicellular organisms, increasingly complex multicellular organisms, and so on up to humans. Consistent complication of the organization leads to an increase in the viability of organisms, their adaptive capabilities.
Irritability and movement. An essential property of living beings irritability(the ability to perceive external or internal stimuli (impact) and adequately respond to them). It manifests itself in changes in metabolism (for example, with a reduction in daylight hours and a decrease in ambient temperature in autumn in plants and animals), in the form of motor reactions (see below), and highly organized animals (including humans) are characterized by changes in behavior.
A characteristic reaction to irritation in almost all living beings is motion,i.e. spatial displacement the whole organism or individual parts of their body. This is characteristic of both unicellular (bacteria, amoeba, ciliates, algae) and multicellular (almost all animals) organisms. Some multicellular cells (for example, blood phagocytes of animals and humans) also have mobility. Multicellular plants, compared with animals, are characterized by low mobility, however, they also have special forms of manifestation of motor reactions. There are two types of active movements: growth And contractile. The first, slower ones, include, for example, stretching towards the light of the stems of house plants growing on the window (due to their one-sided illumination). Contractile movements are observed in insectivorous plants (for example, the rapid folding of the leaves of a sundew when catching insects landing on it).
The phenomenon of irritability underlies the reactions of organisms, due to which they are supported homeostasis.
homeostasis- this is the body's ability to resist changes and maintain the relative constancy of the internal environment (maintaining a certain body temperature, blood pressure, salt composition, acidity, etc.).
Due to irritability, organisms have the ability to adaptation.
Under adaptation refers to the process of adaptation of an organism to certain environmental conditions.
Concluding the section devoted to the determination of the fundamental properties of living organisms, we can draw the following conclusion.
The difference between living organisms and objects of inanimate nature is not in the presence of some "elusive", supernatural properties (all the laws of physics and chemistry are also true for living things), but in the high structural and functional complexity of living systems. This feature includes all the properties of living organisms discussed above and makes the state of life a qualitatively new property of matter.
§ 2. Levels of organization of the living
By the 1960s in biology there is an idea of levels of organization of the living as a concrete expression of the increasingly complex orderliness of the organic world. Life on Earth is represented by organisms of a peculiar structure belonging to certain systematic groups (species), as well as communities of varying complexity (biogeocenosis, biosphere). In turn, organisms are characterized by organ, tissue, cellular and molecular organization. Each organism, on the one hand, consists of specialized organization systems subordinate to it (organs, tissues, etc.), on the other hand, it is itself a relatively isolated unit in the composition of supraorganismal biological systems (species, biogeocenoses and the biosphere as a whole). The levels of organization of living matter are shown in fig. one.
Rice. 1. Levels of organization of the living
All of them exhibit such properties of life as discreteness And integrity. The body consists of various components - organs, but at the same time, thanks to their interaction, it is integral. The species is also an integral system, although it is formed by separate units - individuals, however, their interaction maintains the integrity of the species.
The existence of life at all levels is provided by the structure of the lowest rank. For example, the nature of the cellular level of organization is determined by the subcellular and molecular levels; organismal - organ; tissue, cellular; species - organismic, etc.
Of particular note is the great similarity of organizational units at the lower levels and the ever-increasing difference at the higher levels (Table 1).
Table 1
Characteristics of the levels of organization of the living
Chapter 2
§ 1. Principles of classification of living organisms
The living world of our planet is infinitely diverse and includes a huge number of species of organisms, as can be seen from Table. 2.
table 2
Number of species of major groups of living beings
In fact, according to experts, twice as many species live on Earth today than science knows. Every year, hundreds and thousands of new species are described in scientific publications.
In the process of cognition of numerous objects (objects, phenomena), comparing their properties and signs, people produce classification. Then similar (similar, similar) objects are combined into groups. The division of groups is based on differences between the subjects being studied. In this way, a system is built that encompasses all studied objects (for example, minerals, chemical elements or organisms) and establishes relationships between them.
Systematics how an independent biological discipline deals with problems classification organisms and building systems living nature.
Attempts to classify organisms were made in ancient times. For a long time in science there was a system developed by Aristotle (4th century BC). He divided all known organisms into two kingdoms - plants And animals, using as distinguishing features immobility And insensitivity the first compared to the second. In addition, Aristotle divided all animals into two groups: "animals with blood" and "animals without blood", which generally corresponds to the modern division into vertebrates and invertebrates. Then he singled out a number of smaller groupings, guided by various distinctive features.
Of course, from the standpoint of modern science, Aristotle's system seems imperfect, but it is necessary to take into account the level of factual knowledge of that time. His work describes only 454 species of animals, and the possibilities of research methods were very limited.
For almost two millennia, descriptive material was accumulated in botany and zoology, which ensured the development of taxonomy in the 17th–18th centuries, which culminated in the original system of organisms by C. Linnaeus (1707–1778), which received wide recognition. Based on the experience of his predecessors and new facts discovered by himself, Linnaeus laid the foundations of modern taxonomy. His book, published under the title The System of Nature, was published in 1735.
For the basic unit of classification, Linnaeus took the form; he introduced into scientific use such concepts as "genus", "family", "detachment" and "class"; preserved the division of organisms into the kingdoms of plants and animals. Suggested introduction binary nomenclature(which is still used in biology), i.e., assigning each species a Latin name consisting of two words. The first - a noun - is the name of a genus that unites a group of related species. The second word, usually an adjective, is the name of the species proper. For example, the species "caustic buttercup" and "creeping buttercup"; "golden crucian" and "silver crucian".
Later, at the beginning of the 19th century, J. Cuvier introduced the concept of "type" into the system as the highest unit of classification of animals (in botany - "department").
Of particular importance for the formation of modern taxonomy was the emergence of the evolutionary teachings of Ch. Darwin (1859). The scientific systems of living organisms created in the pre-Darwinian period were artificial. They united organisms into groups according to similar external features quite formally, without attaching importance to their family ties. The ideas of Charles Darwin provided science with a method of constructing natural system living world. This means that it must be based on some essential, fundamental properties of classified objects - organisms.
Let's try as an analogy to build a "natural system" of such objects as books, using the example of a personal library. If desired, we can arrange books on the shelves of cabinets, grouping them either by format or by the color of the spines. But in these cases, an "artificial system" will be created, since "objects" (books) are classified according to secondary, "non-essential" properties. The "natural" "system" would be the library, where books are grouped according to their content. In this cupboard we have scientific literature: on one shelf there are books on physics, on the other - on chemistry, etc. In another cupboard - fiction: prose, poetry, folklore. Thus, we have realized the classification of the available books according to the main property, the essential quality - their content. Having now a "natural system", we can easily orientate ourselves in the multitude of various "objects" that form it. And having acquired a new book, we can easily find a place for it in a specific cabinet and on the appropriate shelf, that is, in the “system”.
Natalya Sergeevna Kurbatova, E. A. Kozlova
General biology
1. History of the development of cell theory
The prerequisites for the creation of the cell theory were the invention and improvement of the microscope and the discovery of cells (1665, R. Hooke - when studying a cut of the bark of a cork tree, elderberry, etc.). The works of famous microscopists: M. Malpighi, N. Gru, A. van Leeuwenhoek - made it possible to see the cells of plant organisms. A. van Leeuwenhoek discovered unicellular organisms in water. The cell nucleus was studied first. R. Brown described the nucleus of a plant cell. Ya. E. Purkine introduced the concept of protoplasm - liquid gelatinous cellular contents.
The German botanist M. Schleiden was the first to come to the conclusion that every cell has a nucleus. The founder of CT is the German biologist T. Schwann (together with M. Schleiden), who in 1839 published the work “Microscopic studies on the correspondence in the structure and growth of animals and plants”. His provisions:
1) cell - the main structural unit of all living organisms (both animals and plants);
2) if there is a nucleus in any formation visible under a microscope, then it can be considered a cell;
3) the process of formation of new cells determines the growth, development, differentiation of plant and animal cells.
Additions to the cellular theory were made by the German scientist R. Virchow, who in 1858 published his work "Cellular Pathology". He proved that daughter cells are formed by division of mother cells: each cell from a cell. At the end of the XIX century. mitochondria, the Golgi complex, and plastids were found in plant cells. Chromosomes were detected after dividing cells were stained with special dyes. Modern provisions of CT
1. Cell - the basic unit of the structure and development of all living organisms, is the smallest structural unit of the living.
2. Cells of all organisms (both unicellular and multicellular) are similar in chemical composition, structure, basic manifestations of metabolism and vital activity.
3. Reproduction of cells occurs by their division (each new cell is formed during the division of the mother cell); in complex multicellular organisms, cells have different shapes and are specialized according to their functions. Similar cells form tissues; tissues consist of organs that form organ systems, they are closely interconnected and subject to nervous and humoral mechanisms of regulation (in higher organisms).
Significance of cell theory
It became clear that the cell is the most important component of living organisms, their main morphophysiological component. The cell is the basis of a multicellular organism, the site of biochemical and physiological processes in the body. At the cellular level, all biological processes ultimately occur. The cell theory made it possible to draw a conclusion about the similarity of the chemical composition of all cells, the general plan of their structure, which confirms the phylogenetic unity of the entire living world.
2. Life. Properties of living matter
Life is a macromolecular open system, which is characterized by a hierarchical organization, the ability to self-reproduce, self-preservation and self-regulation, metabolism, a finely regulated flow of energy.
Properties of living structures:
1) self-updating. The basis of metabolism is balanced and clearly interconnected processes of assimilation (anabolism, synthesis, formation of new substances) and dissimilation (catabolism, decay);
2) self-reproduction. In this regard, living structures are constantly reproduced and updated, without losing their similarity with previous generations. Nucleic acids are capable of storing, transmitting and reproducing hereditary information, as well as realizing it through protein synthesis. Information stored on DNA is transferred to a protein molecule with the help of RNA molecules;
3) self-regulation. It is based on a set of flows of matter, energy and information through a living organism;
4) irritability. Associated with the transfer of information from the outside to any biological system and reflects the reaction of this system to an external stimulus. Thanks to irritability, living organisms are able to selectively react to environmental conditions and extract from it only what is necessary for their existence;
5) maintenance of homeostasis - the relative dynamic constancy of the internal environment of the body, the physico-chemical parameters of the existence of the system;
6) structural organization - orderliness, of a living system, found in the study - biogeocenoses;
7) adaptation - the ability of a living organism to constantly adapt to changing conditions of existence in the environment;
8) reproduction (reproduction). Since life exists in the form of separate living systems, and the existence of each such system is strictly limited in time, the maintenance of life on Earth is associated with the reproduction of living systems;
9) heredity. Provides continuity between generations of organisms (based on information flows). Due to heredity, traits are transmitted from generation to generation that provide adaptation to the environment;
10) variability - due to variability, a living system acquires features that were previously unusual for it. First of all, variability is associated with errors in reproduction: changes in the structure of nucleic acids lead to the emergence of new hereditary information;
11) individual development (the process of ontogenesis) - the embodiment of the initial genetic information embedded in the structure of DNA molecules into the working structures of the body. During this process, such a property as the ability to grow is manifested, which is expressed in an increase in body weight and size;
12) phylogenetic development. Based on progressive reproduction, heredity, struggle for existence and selection. As a result of evolution, a huge number of species appeared;
13) discreteness (discontinuity) and at the same time integrity. Life is represented by a collection of individual organisms, or individuals. Each organism, in turn, is also discrete, since it consists of a set of organs, tissues and cells.
3. Levels of life organization
Living nature is a holistic, but heterogeneous system, which is characterized by a hierarchical organization. A hierarchical system is such a system in which the parts (or elements of the whole) are arranged in order from highest to lowest.
Microsystems (pre-organism stage) include molecular (molecular-genetic) and subcellular levels.
Mesosystems (organismal stage) include cellular, tissue, organ, systemic, organismal (the organism as a whole), or ontogenetic, levels.
Macrosystems (supraorganismal stage) include population-species, biocenotic and global levels (the biosphere as a whole). At each level, one can single out an elementary unit and a phenomenon.
An elementary unit (EE) is a structure (or object), the regular changes of which (elementary phenomena, EE) make its contribution to the development of life at a given level.
Hierarchical levels:
1) molecular genetic level. EE is represented by the genome. A gene is a section of a DNA molecule (and in some viruses, an RNA molecule) that is responsible for the formation of any one trait;
2) subcellular level. EE is represented by some subcellular structure, i.e., an organelle that performs its inherent functions and contributes to the work of the cell as a whole;
3) cellular level. EE is a cell that is a self-functioning elementary
1. Cell theory (CT) Background of the cell theory
The prerequisites for the creation of the cell theory were the invention and improvement of the microscope and the discovery of cells (1665, R. Hooke - when studying a cut of the bark of a cork tree, elderberry, etc.). The works of famous microscopists: M. Malpighi, N. Gru, A. van Leeuwenhoek - made it possible to see the cells of plant organisms. A. van Leeuwenhoek discovered unicellular organisms in water. The cell nucleus was studied first. R. Brown described the nucleus of a plant cell. Ya. E. Purkine introduced the concept of protoplasm - liquid gelatinous cellular contents.
The German botanist M. Schleiden was the first to come to the conclusion that every cell has a nucleus. The founder of CT is the German biologist T. Schwann (together with M. Schleiden), who in 1839 published the work “Microscopic studies on the correspondence in the structure and growth of animals and plants”. His provisions:
1) cell - the main structural unit of all living organisms (both animals and plants);
2) if there is a nucleus in any formation visible under a microscope, then it can be considered a cell;
3) the process of formation of new cells determines the growth, development, differentiation of plant and animal cells. Additions to the cellular theory were made by the German scientist R. Virchow, who in 1858 published his work "Cellular Pathology". He proved that daughter cells are formed by division of mother cells: each cell from a cell. At the end of the XIX century. mitochondria, the Golgi complex, and plastids were found in plant cells. Chromosomes were detected after dividing cells were stained with special dyes. Modern provisions of CT
1. Cell - the basic unit of the structure and development of all living organisms, is the smallest structural unit of the living.
2. Cells of all organisms (both unicellular and multicellular) are similar in chemical composition, structure, basic manifestations of metabolism and vital activity.
3. Reproduction of cells occurs by their division (each new cell is formed during the division of the mother cell); in complex multicellular organisms, cells have different shapes and are specialized according to their functions. Similar cells form tissues; tissues consist of organs that form organ systems, they are closely interconnected and subject to nervous and humoral mechanisms of regulation (in higher organisms).
Significance of cell theory
It became clear that the cell is the most important component of living organisms, their main morphophysiological component. The cell is the basis of a multicellular organism, the site of biochemical and physiological processes in the body. At the cellular level, all biological processes ultimately occur. The cell theory made it possible to draw a conclusion about the similarity of the chemical composition of all cells, the general plan of their structure, which confirms the phylogenetic unity of the entire living world.
2. Definition of life at the present stage of development of science
It is quite difficult to give a complete and unambiguous definition of the concept of life, given the huge variety of its manifestations.
In most definitions of the concept of life, which were given by many scientists and thinkers over the centuries, the leading qualities that distinguish the living from the non-living were taken into account. For example, Aristotle said that life is “nutrition, growth and decrepitude” of the body; A. L. Lavoisier defined life as a "chemical function"; G. R. 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 show that the properties of the living are not exceptional and unique, as it seemed before, they are separately found among non-living objects. AI Oparin defined life as "a special, very complex form of the movement 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 of a general nature and does not reveal the specific peculiarity of this movement.
F. Engels in "Dialectics of Nature" wrote: "Life is a mode of existence of protein bodies, the essential point of which is the exchange of matter and energy with the environment."
For practical application, those definitions are useful, which contain the basic properties that are necessarily inherent in all living forms. Here is one of them: life is a macromolecular open system, which is characterized by a hierarchical organization, the ability to self-reproduce, self-preservation and self-regulation, metabolism, a finely regulated flow of energy. According to this definition, life is a core of order spreading in a less ordered universe.
Life exists in the form of open systems. This means that any living form is not closed only on itself, but constantly exchanges matter, energy and information with the environment.
3. Fundamental properties of living matter
These properties in a complex characterize any living system and life in general:
1) self-updating. Associated with the flow of matter and energy. The basis of metabolism is balanced and clearly interconnected processes of assimilation (anabolism, synthesis, formation of new substances) and dissimilation (catabolism, decay). As a result of assimilation, the body structures are updated and new parts (cells, tissues, parts of organs) are formed. Dissimilation determines the breakdown of organic compounds, provides the cell with plastic matter and energy. For the formation of a new one, a constant influx of necessary substances from the outside is needed, and in the process of life (and dissimilation, in particular), products are formed that need to be brought into the external environment;
2) self-reproduction. Provides continuity between successive generations of biological systems. This property is associated with the information flows embedded in the structure of nucleic acids. In this regard, living structures are constantly reproduced and updated, without losing their similarity with previous generations (despite the continuous renewal of matter). Nucleic acids are capable of storing, transmitting and reproducing hereditary information, as well as realizing it through protein synthesis. Information stored on DNA is transferred to a protein molecule with the help of RNA molecules;
3) self-regulation. It is based on a set of flows of matter, energy and information through a living organism;
4) irritability. Associated with the transfer of information from the outside to any biological system and reflects the reaction of this system to an external stimulus. Thanks to irritability, living organisms are able to selectively react to environmental conditions and extract from it only what is necessary for their existence. Irritability is associated with self-regulation of living systems according to the feedback principle: waste products are able to have an inhibitory or stimulating effect on those enzymes that were at the beginning of a long chain of chemical reactions;
5) maintenance of homeostasis (from Gr. homoios - "similar, identical" and stasis - "immobility, state") - the relative dynamic constancy of the internal environment of the body, the physicochemical parameters of the existence of the system;
6) structural organization - a certain orderliness, harmony of a living system. It is found in the study of not only individual living organisms, but also their aggregates in connection with the environment - biogeocenoses;
7) adaptation - the ability of a living organism to constantly adapt to changing conditions of existence in the environment. It is based on irritability and its characteristic adequate responses;
8) reproduction (reproduction). Since life exists in the form of separate (discrete) living systems (for example, cells), and the existence of each such system is strictly limited in time, the maintenance of life on Earth is associated with the reproduction of living systems. At the molecular level, reproduction is carried out due to matrix synthesis, new molecules are formed according to the program laid down in the structure (matrix) of pre-existing molecules;
9) heredity. Provides continuity between generations of organisms (based on information flows).
It is closely related to the autoreproduction of life at the molecular, subcellular and cellular levels. Due to heredity, traits are transmitted from generation to generation that provide adaptation to the environment;
10) variability is a property opposite to heredity. Due to variability, a living system acquires features that were previously unusual for it. First of all, variability is associated with errors in reproduction: changes in the structure of nucleic acids lead to the emergence of new hereditary information. New signs and properties appear. If they are useful for an organism in a given habitat, then they are picked up and fixed by natural selection. New forms and types are being created. Thus, variability creates prerequisites for speciation and evolution;
11) individual development (the process of ontogenesis) - the embodiment of the initial genetic information embedded in the structure of DNA molecules (i.e., in the genotype) into the working structures of the body. During this process, such a property as the ability to grow is manifested, which is expressed in an increase in body weight and size. This process is based on the reproduction of molecules, reproduction, growth and differentiation of cells and other structures, etc.;
12) phylogenetic development (its patterns were established by C. R. Darwin). Based on progressive reproduction, heredity, struggle for existence and selection. As a result of evolution, a huge number of species appeared. Progressive evolution has gone through a series of stages. These are pre-cellular, unicellular and multicellular organisms up to humans.
At the same time, human ontogeny repeats phylogenesis (i.e., individual development goes through the same stages as the evolutionary process);
13) discreteness (discontinuity) and at the same time integrity. Life is represented by a collection of individual organisms, or individuals. Each organism, in turn, is also discrete, since it consists of a set of organs, tissues and cells. Each cell consists of organelles, but at the same time is autonomous. Hereditary information is carried out by genes, but not a single gene alone can determine the development of a particular trait.
4. Levels of life organization
Living nature is a holistic, but heterogeneous system, which is characterized by a hierarchical organization. A hierarchical system is such a system in which the parts (or elements of the whole) are arranged in order from highest to lowest. The hierarchical principle of organization makes it possible to single out separate levels in living nature, which is very convenient when studying life as a complex natural phenomenon. There are three main stages of life: microsystems, mesosystems and macrosystems.
Microsystems (pre-organism stage) include molecular (molecular-genetic) and subcellular levels.
Mesosystems (organismal stage) include cellular, tissue, organ, systemic, organismal (the organism as a whole), or ontogenetic, levels.
Macrosystems (supraorganismal stage) include population-species, biocenotic and global levels (the biosphere as a whole). At each level, one can single out an elementary unit and a phenomenon.
An elementary unit (EE) is a structure (or object), the regular changes of which (elementary phenomena, EE) make its contribution to the development of life at a given level.
Hierarchical levels:
1) molecular genetic level. EE is represented by the genome. A gene is a section of a DNA molecule (and in some viruses, an RNA molecule) that is responsible for the formation of any one trait. The information embedded in nucleic acids is realized through the matrix synthesis of proteins;
2) subcellular level. EE is represented by some subcellular structure, i.e., an organelle that performs its inherent functions and contributes to the work of the cell as a whole;
3) cellular level. EE is a cell, which is an independently functioning elementary biological system. It is only at this level that the realization of genetic information and the processes of biosynthesis are possible. For unicellular organisms, this level coincides with the organism level. EE are the reactions of cellular metabolism, which form the basis of the flows of energy, information and matter;
4) tissue level. A set of cells with the same type of organization constitutes a tissue (EE). The level arose with the advent of multicellular organisms with more or less differentiated tissues. The tissue functions as a whole and has the properties of a living thing;
5) organ level. It is formed together with functioning cells belonging to different tissues (EE). Only four main tissues are part of the organs of multicellular organisms, six main tissues form the organs of plants;
6) organismic (ontogenetic) level. EE is an individual in its development from the moment of birth to the termination of its existence as a living system. EI are regular changes in the body in the process of individual development (ontogenesis). In the process of ontogenesis, under certain environmental conditions, hereditary information is embodied in biological structures, i.e., on the basis of the genotype of an individual, its phenotype is formed;
7) population-species level. EE is a population, i.e., a set of individuals (organisms) of the same species that inhabit the same territory and freely interbreed. The population has a gene pool, i.e., the totality of the genotypes of all individuals. The impact on the gene pool of elementary evolutionary factors (mutations, fluctuations in the number of individuals, natural selection) leads to evolutionarily significant changes (ER);
8) biocenotic (ecosystem) level. EE - biocenosis, i.e., a historically established stable community of populations of different species, connected with each other and with the surrounding inanimate nature by the exchange of substances, energy and information (cycles), which represent the EE;
9) biosphere (global) level. EE - the biosphere (the area of \u200b\u200bdistribution of life on Earth), that is, a single planetary complex of biogeocenoses, different in species composition and characteristics of the abiotic (non-living) part. Biogeocenoses determine all processes occurring in the biosphere;
10) nospheric level. This new concept was formulated by Academician V. I. Vernadsky. He founded the doctrine of the noosphere as the sphere of the mind. This is an integral part of the biosphere, which is changed due to human activities.
LECTURE № 2. Chemical composition of living systems. The biological role of proteins, polysaccharides, lipids and ATP
1. Overview of the chemical structure of the cell
All living systems contain chemical elements in various proportions and chemical compounds built from them, both organic and inorganic.
According to the quantitative content in the cell, all chemical elements are divided into 3 groups: macro-, micro- and ultramicroelements.
Macronutrients make up to 99% of the cell mass, of which up to 98% is accounted for by 4 elements: oxygen, nitrogen, hydrogen and carbon. In smaller quantities, cells contain potassium, sodium, magnesium, calcium, sulfur, phosphorus, and iron.
Trace elements are predominantly metal ions (cobalt, copper, zinc, etc.) and halogens (iodine, bromine, etc.). They are contained in amounts from 0.001% to 0.000001%.
Ultramicroelements. Their concentration is below 0.000001%. These include gold, mercury, selenium, etc.
A chemical compound is a substance in which the atoms of one or more chemical elements are connected to each other through chemical bonds. Chemical compounds are inorganic and organic. Inorganic include water and mineral salts. Organic compounds are compounds of carbon with other elements.
The main organic compounds of the cell are proteins, fats, carbohydrates and nucleic acids.
2. Biopolymers Proteins
These are polymers whose monomers are amino acids. They are mainly composed of carbon, hydrogen, oxygen and nitrogen. A protein molecule can have 4 levels of structural organization (primary, secondary, tertiary and quaternary structures).
Protein Functions:
1) protective (interferon is intensively synthesized in the body during a viral infection);
2) structural (collagen is part of tissues, participates in scar formation);
3) motor (myosin is involved in muscle contraction);
4) spare (egg albumins);
5) transport (erythrocyte hemoglobin carries nutrients and metabolic products);
6) receptor (receptor proteins provide recognition by the cell of substances and other cells);
7) regulatory (regulatory proteins determine the activity of genes);
8) hormone proteins are involved in humoral regulation (insulin regulates blood sugar levels);
9) enzyme proteins catalyze all chemical reactions in the body;
10) energy (the breakdown of 1 g of protein releases 17 kJ of energy).
Carbohydrates
These are mono- and polymers, which include carbon, hydrogen and oxygen in a ratio of 1: 2: 1.
Functions of carbohydrates:
1) energy (with the breakdown of 1 g of carbohydrates, 17.6 kJ of energy is released);
2) structural (cellulose, which is part of the cell wall in plants);
3) storage (supply of nutrients in the form of starch in plants and glycogen in animals).
Fats (lipids) can be simple or complex. Simple lipid molecules consist of the trihydric alcohol glycerol and three fatty acid residues. Complex lipids are compounds of simple lipids with proteins and carbohydrates.
Lipid functions:
1) energy (with the breakdown of 1 g of lipids, 38.9 kJ of energy is formed);
2) structural (phospholipids of cell membranes forming a lipid bilayer);
3) storage (supply of nutrients in the subcutaneous tissue and other organs);
4) protective (subcutaneous tissue and a layer of fat around the internal organs protect them from mechanical damage);
5) regulatory (hormones and vitamins containing lipids regulate metabolism);
6) heat-insulating (subcutaneous tissue retains heat). ATP
The ATP (adenosine triphosphoric acid) molecule consists of the nitrogenous base of adenine, the five-carbon sugar of ribose, and three phosphoric acid residues interconnected by a macroergic bond. ATP is produced in mitochondria by phosphorylation. During its hydrolysis, a large amount of energy is released. ATP is the main macroerg of the cell - an energy accumulator in the form of energy of high-energy chemical bonds.
LECTURE № 3. Nucleic acids. Protein biosynthesis
Nucleic acids are phosphorus-containing biopolymers whose monomers are nucleotides. Nucleic acid chains include from several tens to hundreds of millions of nucleotides.
There are 2 types of nucleic acids - deoxyribonucleic acid (DNA) and ribonucleic acid (RNA). The nucleotides that make up DNA contain a carbohydrate, deoxy-ribose, while RNA contains ribose.
1. DNA
As a rule, DNA is a helix consisting of two complementary polynucleotide chains twisted to the right. The composition of DNA nucleotides includes: a nitrogenous base, deoxyribose and a phosphoric acid residue. Nitrogenous bases are divided into purine (adenine and guanine) and pyrimidine (thymine and cytosine). Two chains of nucleotides are connected to each other through nitrogenous bases according to the principle of complementarity: two hydrogen bonds occur between adenine and thymine, and three between guanine and cytosine.
DNA functions:
1) ensures the preservation and transmission of genetic information from cell to cell and from organism to organism, which is associated with its ability to replicate;
2) regulation of all processes occurring in the cell, provided by the ability to transcription with subsequent translation.
The process of self-reproduction (auto-reproduction) of DNA is called replication. Replication ensures the copying of genetic information and its transmission from generation to generation, the genetic identity of daughter cells formed as a result of mitosis, and the constancy of the number of chromosomes during mitotic cell division.
Replication occurs during the synthetic period of the interphase of mitosis. The replicase enzyme moves between the two strands of the DNA helix and breaks the hydrogen bonds between the nitrogenous bases. Then, to each of the chains, with the help of the DNA polymerase enzyme, the nucleotides of the daughter chains are completed according to the principle of complementarity. As a result of replication, two identical DNA molecules are formed. The amount of DNA in a cell doubles. This method of DNA duplication is called semi-conservative, since each new DNA molecule contains one "old" and one newly synthesized polynucleotide chain.
The textbook reflects the current state of science on the general patterns of the origin and development of life on Earth. Part I of the textbook includes sections: "Introduction", "Life as a natural phenomenon", "Biology of the cell", "Reproduction of organisms", "Organization of hereditary material", "Patterns of inheritance" and "Variability".
The textbook is intended for university students studying in biological, medical and agricultural specialties.
properties of the living.
Living organisms, unlike bodies of inanimate nature, are characterized by a number of properties that are, in fact, attributes of life: orderliness and specificity of structure, integrity and discreteness, self-regulation and homeostasis, self-reproduction and self-healing, heredity and variability, metabolism and energy, growth and development, irritability, movement, self-regulation, specific relationship with the environment, aging and death, involvement in the continuous process of historical changes of the living (evolutionary process). These attributes of life are the objects of research by many independent biological sciences, the results of which are presented below in various sections of the textbook. However, some of them are reasonably classified as fundamental and require special consideration already at the beginning of the General Biology course.
Orderliness and specificity of the structure. Living organisms contain the same chemical elements as in the objects of wildlife. However, in the cells of living beings, they are in the form of not only inorganic, but also organic compounds. In addition, the form of existence of living things has very significant specific features, primarily complexity and orderliness, which distinguish both the molecular and supramolecular levels of organization. The creation of order is the most important property of the living. Order in space is accompanied by order in time.
Table of contents
INTRODUCTION 3
CHAPTER 1. LIFE AS A NATURAL PHENOMENA 9
1.1. Defining the Essence of Life 9
1.2. Substratum of life 10
1.3. Properties of living 11
1.4. Fundamental properties of life 12
1.5. Levels of organization of life 13
CHAPTER 2. CELL BIOLOGY 16
2.1. Cell is an elementary structural-functional and genetic unit of life 16
2.2. The main stages of development and the current state of cell theory 16
2.3. Structural organization of prokaryotic and eukaryotic cells 20
2.4. Surface cell apparatus 23
2.5. Cytoplasmic apparatus of the cell 30
2.5.1. Hyaloplasm 30
2.5.2. Cell organelles (organelles) 32
2.5.2.1. Membrane organelles (organelles) 34
2.5.2.2. Non-membrane organelles (organelles) 41
2.6. Nuclear apparatus of the cell 49
2.7. Cell life cycle 55
2.7.1. The concept of the cell life cycle 55
2.7.2. Interphase 56
2.7.2.1. Post-mitotic period 57
2.7.2.2. synthetic period. DNA self-duplication 57
2.7.2.3. Premitotic period 64
2.7.2.4. Mitotic period 65
2.7.2.5. Cell renewal in cell populations 69
2.7.2.6. Cell response to adverse effects 70
2.7.2.7. Cell dystrophy 70
CHAPTER 3. REPRODUCTION OF ORGANISMS 73
3.1. Reproduction is a universal property of the living. The evolution of reproduction 73
3.2. Asexual reproduction 73
3.2.1. Monocytogenic asexual reproduction 73
3.2.2. Polycytogenic asexual reproduction 75
3.3. Sexual reproduction 76
3.3.1. The evolution of sexual reproduction 77
3.3.2. Gametogenesis 82
3.3.3. Fertilization 91
3.4. Ways of interspecies exchange of biological information 92
3.5. Biological aspects of sexual dimorphism 95
CHAPTER 4. ORGANIZATION OF HEREDITARY MATERIAL 97
4.1. Subject, tasks and methods of genetics. Stages of development of genetics 97
4.2. Structural and functional levels of organization of hereditary material 100
4.3. Gene as a functional unit of heredity. Classification, properties and localization of genes 102
4.4. The main provisions of the chromosome theory of heredity 108
CHAPTER 5. PATTERNS OF INHERITANCE
5.1. Heredity as a property of ensuring material continuity between generations 110
5.2. Types and patterns of inheritance 111
5.3. Phenotype as a result of the realization of the genotype in certain environmental conditions 117
5.4. Molecular biological ideas about the structure and functioning of genes. Gene expression and its regulation 118
5.5. Interaction of genes 122
5.5.1. Interaction of allelic genes 122
5.5.2. Interaction of non-allelic genes 125
5.6. Pleiotropy 129
5.7. Multiple allelism 131
5.8. expressiveness and penetrance. Genocopies 133
5.9. Genetic engineering 134
CHAPTER 6. VARIABILITY 137
6.1. Variability as a universal property of the living 137
6.2. Modification variability, its adaptive nature, significance of ontogeny and evolution 138
6.3. Statistical methods for studying modification variability 143
6.4. Genotypic variability. Mechanisms and biological 146.
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The prerequisites for the creation of the cell theory were the invention and improvement of the microscope and the discovery of cells (1665, R. Hooke - when studying a cut of the bark of a cork tree, elderberry, etc.). The works of famous microscopists: M. Malpighi, N. Gru, A. van Leeuwenhoek - made it possible to see the cells of plant organisms. A. van Leeuwenhoek discovered unicellular organisms in water. The cell nucleus was studied first. R. Brown described the nucleus of a plant cell. Ya. E. Purkine introduced the concept of protoplasm - liquid gelatinous cellular contents.
The German botanist M. Schleiden was the first to come to the conclusion that every cell has a nucleus. The founder of CT is the German biologist T. Schwann (together with M. Schleiden), who in 1839 published the work “Microscopic studies on the correspondence in the structure and growth of animals and plants”. His provisions:
1) cell - the main structural unit of all living organisms (both animals and plants);
2) if there is a nucleus in any formation visible under a microscope, then it can be considered a cell;
3) the process of formation of new cells determines the growth, development, differentiation of plant and animal cells. Additions to the cellular theory were made by the German scientist R. Virchow, who in 1858 published his work "Cellular Pathology". He proved that daughter cells are formed by division of mother cells: each cell from a cell. At the end of the XIX century. mitochondria, the Golgi complex, and plastids were found in plant cells. Chromosomes were detected after dividing cells were stained with special dyes. Modern provisions of CT
1. Cell - the basic unit of the structure and development of all living organisms, is the smallest structural unit of the living.
2. Cells of all organisms (both unicellular and multicellular) are similar in chemical composition, structure, basic manifestations of metabolism and vital activity.
3. Reproduction of cells occurs by their division (each new cell is formed during the division of the mother cell); in complex multicellular organisms, cells have different shapes and are specialized according to their functions. Similar cells form tissues; tissues consist of organs that form organ systems, they are closely interconnected and subject to nervous and humoral mechanisms of regulation (in higher organisms).
Significance of cell theory
It became clear that the cell is the most important component of living organisms, their main morphophysiological component. The cell is the basis of a multicellular organism, the site of biochemical and physiological processes in the body. At the cellular level, all biological processes ultimately occur. The cell theory made it possible to draw a conclusion about the similarity of the chemical composition of all cells, the general plan of their structure, which confirms the phylogenetic unity of the entire living world.
2. Definition of life at the present stage of development of science
It is quite difficult to give a complete and unambiguous definition of the concept of life, given the huge variety of its manifestations. In most definitions of the concept of life, which were given by many scientists and thinkers over the centuries, the leading qualities that distinguish the living from the non-living were taken into account. For example, Aristotle said that life is “nutrition, growth and decrepitude” of the body; A. L. Lavoisier defined life as a "chemical function"; G. R. 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 show that the properties of the living are not exceptional and unique, as it seemed before, they are separately found among non-living objects. AI Oparin defined life as "a special, very complex form of the movement 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 of a general nature and does not reveal the specific peculiarity of this movement.
F. Engels in "Dialectics of Nature" wrote: "Life is a mode of existence of protein bodies, the essential point of which is the exchange of matter and energy with the environment."
For practical application, those definitions are useful, which contain the basic properties that are necessarily inherent in all living forms. Here is one of them: life is a macromolecular open system, which is characterized by a hierarchical organization, the ability to self-reproduce, self-preservation and self-regulation, metabolism, a finely regulated flow of energy. According to this definition, life is a core of order spreading in a less ordered universe.
Life exists in the form of open systems. This means that any living form is not closed only on itself, but constantly exchanges matter, energy and information with the environment.
3. Fundamental properties of living matter
These properties in a complex characterize any living system and life in general:
1) self-updating. Associated with the flow of matter and energy. The basis of metabolism is balanced and clearly interconnected processes of assimilation (anabolism, synthesis, formation of new substances) and dissimilation (catabolism, decay). As a result of assimilation, the body structures are updated and new parts (cells, tissues, parts of organs) are formed. Dissimilation determines the breakdown of organic compounds, provides the cell with plastic matter and energy. For the formation of a new one, a constant influx of necessary substances from the outside is needed, and in the process of life (and dissimilation, in particular), products are formed that need to be brought into the external environment;
2) self-reproduction. Provides continuity between successive generations of biological systems. This property is associated with the information flows embedded in the structure of nucleic acids. In this regard, living structures are constantly reproduced and updated, without losing their similarity with previous generations (despite the continuous renewal of matter). Nucleic acids are capable of storing, transmitting and reproducing hereditary information, as well as realizing it through protein synthesis. Information stored on DNA is transferred to a protein molecule with the help of RNA molecules;
3) self-regulation. It is based on a set of flows of matter, energy and information through a living organism;
4) irritability. Associated with the transfer of information from the outside to any biological system and reflects the reaction of this system to an external stimulus. Thanks to irritability, living organisms are able to selectively react to environmental conditions and extract from it only what is necessary for their existence. Irritability is associated with self-regulation of living systems according to the feedback principle: waste products are able to have an inhibitory or stimulating effect on those enzymes that were at the beginning of a long chain of chemical reactions;
5) maintenance of homeostasis (from Gr. homoios - "similar, identical" and stasis - "immobility, state") - the relative dynamic constancy of the internal environment of the body, the physicochemical parameters of the existence of the system;
6) structural organization - a certain orderliness, harmony of a living system. It is found in the study of not only individual living organisms, but also their aggregates in connection with the environment - biogeocenoses;
7) adaptation - the ability of a living organism to constantly adapt to changing conditions of existence in the environment. It is based on irritability and its characteristic adequate responses;
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