small molecules- These are biomolecules with a relatively small molecular weight from 100 to 1000, which contain up to 30 carbon atoms. Small molecules account for about 3% of total mass cells.

Features of small molecules. They are located in a free state in the cytoplasm of the cell, due to which they can quickly move due to diffusion (on average, at a distance of 10 microns 0.2 s). Quite often they appear as monomers: monomers of polysaccharides are monosaccharides, proteins - amino acids, nucleic acids - nucleotides. Monomers- simple molecules that are links in the chains of biopolymer macromolecules. they have the ability to polymerization, therefore, they contain groups that react with certain groups of other monomers to form covalent bonds. The combination of small molecules occurs by removing a water molecule during condensation reactions, and decay - as a result of a limited number of chemical transformations in those products from which they were synthesized. In molecules, certain simple combinations of atoms are repeatedly repeated - functional groups- chemical and physical properties of which determine the behavior of any molecules OH - hydroxyl group, NH2 - amino group, COOH - carboxyl group, etc.

biological significance. The functions of small molecules in living organisms are not diverse, but very important for them. These are: 1) construction - participation in the formation of other, more complex molecules; 2) energy - participation in biochemical reactions of energy metabolism; 3) regulatory - participation in the regulation of processes and functions.

Variety of small molecules

The main families of small molecules include fatty acids, simple sugars, amino acids And nucleotides.

Monosaccharides (simple sugars ) - This is a group of carbohydrates, the molecules of which have from three to ten carbon atoms in their composition. The general formula of monosaccharides is CnH2nOn. The content in the cell is about 1% of the total mass of the cell. They can have, with the same chemical composition, a different order of bonds between atoms or groups of atoms, which determines the existence structural isomers with different chemical properties(for example, glucose and fructose formula C6H12O6). By physical properties these are white crystalline substances, sweet in taste (fructose is sweet - 5 times sweeter than glucose), highly soluble in water, alcohols and insoluble in polar solvents. Due to the presence of several hydroxyl groups, they are capable of polymerization, form a large number of oligo- and polysaccharides, in which they are combined with glycosidic bonds. They are synthesized from CO2 and water during photosynthesis in plants and during gluconeogenesis in animals. Decay carried out by oxidation with the formation of CO2 and H2O with the release of a large amount of energy (for example, the oxidation of one glucose molecule is accompanied by the formation of 38 ATP molecules). In monosaccharides, there is a dependence of properties on the chemical composition, spatial arrangement of groups, the ability to rotate the plane of polarized light, the presence and number of functional groups, etc. Monosaccharides can exist in two forms - linear, when the carbohydrate chain is open, and cyclical, when it is closed.

More than 50 different natural monosaccharides have already been described in the biochemistry of carbohydrates. The most common is their classification depending on the number of carbon atoms in the molecule, according to which the names of monosaccharide groups are formed from the Greek name of the numeral, which corresponds to this number with the addition of the ending -ose(trioses, tetroses, pentoses, hexoses, heptoses, octose, nanoses, decoses). Pentoses and hexoses are of the greatest importance in living nature. Pentoses is a group of monosaccharides whose molecules contain five carbon atoms. With pentoses, ribose and deoxyribose are known, which are part of ribonucleic (RNA) and deoxyribonucleic (DNA) acids, respectively. Hexoses - This is a group of monosaccharides whose molecules contain six carbon atoms. In nature, glucose and fructose are the most common, the sweet taste of berries and honey depends on the content of which.

They are distributed in organisms both in the free state and as part of oligosaccharides, polysaccharides, etc. They play an important role in the metabolism involved in the processes of cellular respiration, fermentation and the synthesis of complex carbohydrates. The main functions are energy(when splitting 1 g, 17.6 kJ of energy is released) and structures

tour(there are monomers of complex carbohydrates). Such derivatives of monosaccharides as sugar alcohols (for example, mannitol in brown algae as a storage compound), sugar acids (ascorbic acid, uronic acids), glycosides (lily of the valley cardiac glycosides).

Fatty acid - is a group of small organic molecules that are chemically monobasic carboxylic acids. The general formula of fatty acids is CH3 - (CH2) n - COOH. There are two distinct parts to the molecule: a long hydrophobic carboxylic chain and a hydrophilic carboxyl group. Their content in the cell is about 1% of the total mass of the cell. Fatty acids differ in their melting point and solubility in water and organic solvents. An increase in the number of carbon atoms in molecules is accompanied by a decrease in solubility in water and an increase in the melting point.

In water, their molecules can form a surface film or small micelles (particles in colloidal systems consisting of a hydrophobic core and a hydrophilic shell). Fatty acids combine with alcohols to form lipids ester bonds. Their decomposition is carried out by oxidation with the formation of acetyl-CoA, CO2 and H2O with the release of a large amount of energy (for example, the oxidation of one molecule of palmitic acid is accompanied by the formation of 130 ATP molecules). In fatty acids, there is a dependence of properties on the chemical composition, the presence of double bonds, etc.

According to the number of carbon atoms, fatty acids are divided into lower(up to 3 carbons), medium(4-9 carbons) and higher(9-24 carbons). According to the features of the connections, they distinguish saturated [NOT have double bonds) and unsaturated(may have one, two or more double bonds). The most common fatty acids are saturated fatty acids such as oily, palmitic, stearic, arachidic, and unsaturated fatty acids such as oleic, linoleic, linolenic, arachidonic.

Fatty acids are common in organisms both in the free state and as part of simple and complex lipids. But the most important manifestation of the structural function of fatty acids is their participation in the construction of phospholipids of cell membranes. Fatty acids are a valuable source of energy, since their breakdown is accompanied by the release of twice as much energy as the breakdown of the same mass of glucose. unsaturated fatty acids ( linoleic, linolenic, arachidonic), which are conventionally grouped under the name "vitamin F", participate in the processes of growth and development of the body, enhance protective reactions, and the like. The lack of this vitamin in the body of animals leads to the cessation of growth, causes dermatitis and diseases of the internal organs. So, fatty acids are characterized by structural, energy, and regulatory functions.

Amino acids- These are small organic molecules, which include an amino group and a carboxyl group. Their content in the cell is 0.4% of the total mass of the cell. Their general formula includes a COOH carboxyl group, an NH2 amino group, and a radical group, which is different in different amino acids and distinguishes them from each other. By physical power

Palmitic acid(C15H31COOH)

Amino acids themselves are colorless crystalline substances, most of which are soluble in water. They may have a sweetish, bitter taste, a specific smell, but most are generally tasteless and odorless. All are thermally unstable. Amino acids are capable of polymerization, forming peptides and proteins. In most amino acids, there is one COOH (causes acidic properties) and one NH2 (causes basic properties), which together determine the amphoteric properties of amino acids. Due to the ability of the amino group and the carboxyl "group to ionize, ionic bonds, during the interaction of sulfhydryl groups (-SH) of sulfur-containing amino acid radicals, disulfide nor bond, when hydrogen interacts with 0 or N in the groups - OH or -NH, hydrogen bonds, and when NH2 of one amino acid interacts with COOH of another, with the release of water, peptide bonds . with an increase in pH, they act as donors of H + -ions, and with a decrease in the role of acceptors of these ions, which indicates their ability to act as a buffer in solutions. In amino acids, there is a dependence of properties on the chemical composition, composition of radicals, the number of functional groups, pH on the action of polarized light, etc.

In total, more than 200 amino acids have been isolated from natural sources. they are classified according to the structure of the radical, the number of functional groups, etc. According to the biological characteristics, amino acids are divided into interchangeable(e.g. alanine, asparagine) and irreplaceable(leucine, valine). The former are synthesized in the body of humans and animals, while others are not synthesized and enter them only with food. For normal life, the body needs a complete set of 20 basic L-amino acids and certain additional amino acids that are derived from the main ones.

Names of the main amino acids and their abbreviations

Amino acid name	abbreviation	Variables (s) and constants (n)

		(C) - for children (n)
asparagine
aspartic acid

histidine		(C) - for children (n)

glutamine
glutamic acid
isoleucine


methionine




tryptophan
phenylalanine

The importance of amino acids is primarily due to the fact that they are protein monomers (structural function) and a source of energy (energy function). However, amino acids also perform some specific functions. For example, the thyroid hormone thyroxine is synthesized from tyrosine.

Nucleotides - organic compounds whose molecules consist of a nitrogenous base, a monosaccharide and residues phosphoric acid. The content in the cell is 0.4% of the total mass of the cell. So, the composition of nucleotide molecules includes: 1) a nitrogenous (nitrogen) base (A - adenine, or G - guanine, or T - thymine, or C - cytosine, or B - uracil) 2) a carbohydrate that represents pentoses (ribose or deoxyribose) and phosphoric acid. The combination of a nitrogenous base from pentoses is called a nucleoside. Nucleotides are highly soluble in water. They are capable of polymerization, forming nucleic acids (RNA and DNA). They exhibit the properties of acids, as they contain phosphoric acid, and due to nitrogenous bases - basic properties. Nucleotides have two types of covalent bonds: glycosidic(between nitrogenous base and pentose) and phosphoethernium(between pentose and phosphate residue).

Nucleotides combine to form a polynucleotide chain to form an internucleotide chain. 3", 5"-phosphodiester bond between the pentoses of one nucleotide and the phosphate of another. Nucleotides of two chains are combined on the basis of the principle of structural complementarity with the help of hydrogen bonds. The properties of nucleotides depend on the composition of nitrogenous bases, pentoses, and the number of phosphate residues.

Nucleotides are divided into ribonucleotides (adenyl, uridyl, guanyl and cytidyl) and deoxyribonucleotides (adenyl, thymidyl, guanyl and cytidilovium). The derivatives of nucleotides are nucleoside diphosphates(nucleotides with two phosphoric acid residues, for example, ADP, GDP), nucleoside triphosphates(nucleotides with three phosphoric acid residues, e.g. ATP, GTP, TTP, CTP), NADP, NAD, FAD and others

Nucleotides are the "building" subunits of nucleic acids; in combination with other groups, they form coenzymes in the composition of enzyme systems, for example, NADP, FAD ( structural function) , participate in the energy metabolism of cells, for example, ATP ( energy function) , involved in the transmission of humoral signals into the cell, for example, cyclic AMP ( regulatory function) and etc.

Adenosine triphosphoric acid - an organic compound belonging to free nucleotides and is a universal chemical energy accumulator in the cell. The ATP molecule is a nucleotide which consists of adenine, ribose and three phosphates. With the hydrolytic cleavage of the phosphate group from ATP, about 42 kJ of energy is released and ADP (adenosine diphosphoric acid) is formed. When from ATP molecules two phosphates are split off, AMP (adenosine monophosphoric acid) is formed and 84 kJ of energy is released.

In the reverse process, when ATP is formed from ADP or AMP and inorganic phosphate, energy is accumulated in macroergic bonds that arise between phosphoric acid residues. The processes of splitting and formation of ATP occur constantly in accordance with the scheme:

So, the main function of ATP is energy, as it participates in energy metabolism, storing a significant amount of energy in its macroergic bonds. In addition to the energy function of ATP in cells, it is also a universal source of phosphate groups.

Most macromolecules can be combined into several classes: proteins, nucleic acids, carbohydrates and lipids.

Encyclopedia "Avanta +"

Squirrels (proteins, polypeptides) are the most numerous, most diverse and of paramount importance biopolymers. The composition of protein molecules includes atoms of carbon, oxygen, hydrogen, nitrogen and sometimes sulfur, phosphorus and iron.

Protein monomers are amino acids, which (having in their composition carboxyl and amino groups) have the properties of an acid and a base (amphoteric).

Due to this, amino acids can combine with each other (their number in one molecule can reach several hundred). As a result, protein molecules are big sizes and they are called macromolecules.

Structure of a protein molecule

Under the structure of a protein molecule understand its amino acid composition, the sequence of monomers and the degree of twisting of the protein molecule.

In protein molecules, there are only 20 types of different amino acids, and a huge variety of proteins is created due to their various combinations.

The sequence of amino acids in a polypeptide chain is primary structure squirrel(it is unique to any protein and determines its shape, properties and functions). The primary structure of a protein is unique to any type of protein and determines the shape of its molecule, its properties and functions.
A long protein molecule folds and first takes the form of a spiral as a result of the formation of hydrogen bonds between the -CO and -NH groups of different amino acid residues of the polypeptide chain (between the carbon of the carboxyl group of one amino acid and the nitrogen of the amino group of another amino acid). This spiral is protein secondary structure.
Tertiary structure of a protein- three-dimensional spatial “packing” of the polypeptide chain in the form globules(ball). The strength of the tertiary structure is provided by a variety of bonds that arise between amino acid radicals (hydrophobic, hydrogen, ionic and disulfide S-S bonds).
Some proteins (such as human hemoglobin) have quaternary structure. It arises as a result of the combination of several macromolecules with a tertiary structure into a complex complex. The quaternary structure is held together by fragile ionic, hydrogen, and hydrophobic bonds.

The structure of proteins can be disturbed (subjected to denaturation) when heated, treated with certain chemicals, irradiation, etc. With a weak effect, only the quaternary structure breaks down, with a stronger effect, the tertiary, and then the secondary, and the protein remains in the form of a polypeptide chain. As a result of denaturation, the protein loses its ability to perform its function.

Violation of the quaternary, tertiary and secondary structures is reversible. This process is called renaturation.

The destruction of the primary structure is irreversible.

In addition to simple proteins, consisting only of amino acids, there are also complex proteins, which may include carbohydrates ( glycoproteins), fats ( lipoproteins), nucleic acids ( nucleoproteins) and etc.

Functions of proteins

Catalytic (enzymatic) function. Special proteins - enzymes- capable of accelerating biochemical reactions in the cell by tens and hundreds of millions of times. Each enzyme speeds up one and only one reaction. Enzymes contain vitamins.

Structural (building) function- one of the main functions of proteins (proteins are part of cell membranes; keratin protein forms hair and nails; collagen and elastin proteins - cartilage and tendons).

transport function- proteins provide active transport of ions through cell membranes(transport proteins in the outer membrane of cells), transport of oxygen and carbon dioxide(blood hemoglobin and myoglobin in muscles), transport of fatty acids (blood serum proteins contribute to the transfer of lipids and fatty acids, various biologically active substances).

Signal function. The reception of signals from the external environment and the transmission of information to the cell occurs due to proteins built into the membrane that can change their tertiary structure in response to environmental factors.
Contractile (motor) function- provided by contractile proteins - actin and myosin (due to contractile proteins, cilia and flagella move in protozoa, chromosomes move during cell division, muscles contract in multicellular organisms, other types of movement in living organisms improve).

Protective function- Antibodies provide immune defense of the body; fibrinogen and fibrin protect the body from blood loss by forming a blood clot.

Regulatory function inherent in proteins hormones(not all hormones are proteins!). They maintain constant concentrations of substances in the blood and cells, participate in growth, reproduction and other vital functions. important processes(for example, insulin regulates blood sugar levels).
energy function- during prolonged fasting, proteins can be used as an additional source of energy after carbohydrates and fats have been consumed (with complete splitting 1 g of protein to end products releases 17.6 kJ of energy). Amino acids released during the breakdown of protein molecules are used to build new proteins.

Proteins are biological polymers with a complex structure. They have a high molecular weight and consist of amino acids, prosthetic groups represented by vitamins, lipid and carbohydrate inclusions. Proteins containing carbohydrates, vitamins, metals or lipids are called complex. Simple proteins consist only of amino acids linked by peptide bonds.

Peptides

Regardless of the structure of the substance, the monomers of proteins are amino acids. They form the basic polypeptide chain, from which the fibrillar or globular structure of the protein is then formed. At the same time, protein can only be synthesized in living tissue - in plant, bacterial, fungal, animal and other cells.

The only organisms that cannot combine protein monomers are viruses and protozoa. All others are able to form structural proteins. But what substances are protein monomers, and how are they formed? About this and about polypeptides and structure formation, about amino acids and their properties, read below.

The only monomer of a protein molecule is any alpha-amino acid. A protein is a polypeptide, a chain of linked amino acids. Depending on the number of amino acids involved in its formation, dipeptides (2 residues), tripeptides (3), oligopeptides (contains from 2-10 amino acids) and polypeptides (many amino acids) are isolated.

Overview of protein structure

The structure of a protein can be primary, slightly more complex - secondary, even more complex - tertiary, and the most complex - quaternary.

The primary structure is a simple chain into which protein monomers (amino acids) are connected through a peptide bond (CO-NH). The secondary structure is the alpha helix or beta folds. Tertiary is an even more complicated three-dimensional protein structure, which was formed from the secondary due to the formation of covalent, ionic and hydrogen bonds, as well as hydrophobic interactions.

The quaternary structure is the most complex and is characteristic of receptor proteins located on cell membranes. This is a supramolecular (domain) structure formed as a result of the combination of several molecules with a tertiary structure, supplemented with carbohydrate, lipid or vitamin groups. In this case, as in the case of primary, secondary and tertiary structures, the monomers of proteins are alpha-amino acids. They are also connected by peptide bonds. The only difference is the complexity of the structure.

Amino acids

The only monomers of protein molecules are alpha-amino acids. There are only 20 of them, and they are almost the basis of life. Thanks to the advent of the peptide bond, it became possible. And the protein itself after that began to perform structure-forming, receptor, enzymatic, transport, mediator and other functions. Thanks to this, a living organism functions and is able to reproduce.

The alpha amino acid itself is an organic carboxylic acid with an amino group attached to the alpha carbon atom. The latter is located next to the carboxyl group. In this case, protein monomers are considered as in which the terminal carbon atom carries both an amine and a carboxyl group.

Connection of amino acids in peptides and proteins

Amino acids are linked into dimers, trimers, and polymers via peptide bonds. It is formed by cleavage of a hydroxyl (-OH) group from the carboxyl site of one alpha-amino acid and hydrogen (-H) from the amino group of another alpha-amino acid. As a result of the interaction, water is split off, and a C=O site with a free electron near the carbon of the carboxyl residue remains at the carboxyl end. In the amino group of another acid, there is a residue (NH) with a nitrogen atom present. This allows two radicals to be connected to form a bond (CONH). It's called peptide.

Alpha amino acid variants

A total of 23 alpha-amino acids are known. They are listed as follows: glycine, valine, alanine, isolecine, leucine, glutamate, aspartate, ornithine, threonine, serine, lysine, cystine, cysteine, phenylalanine, methionine, tyrosine, proline, tryptophan, hydroxyproline, arginine, histidine, asparagine and glutamine. Depending on whether they can be synthesized by the human body, these amino acids are divided into nonessential and irreplaceable.

The concept of nonessential and essential amino acids

The human body can synthesize the essentials, while the essentials must be supplied only with food. At the same time, both essential and non-essential acids are important for protein biosynthesis, because without them the synthesis cannot be completed. Without one amino acid, even if all the others are present, it is impossible to build exactly the protein that the cell needs to perform its functions.

One mistake at any of the stages of biosynthesis - and the protein is no longer suitable, because it will not be able to assemble into the desired structure due to a violation of electronic densities and interatomic interactions. Therefore, it is important for a person (and other organisms) to consume in which there are essential amino acids. Their absence in food leads to a number of violations of protein metabolism.

The process of formation of a peptide bond

The only monomers of proteins are alpha-amino acids. They are gradually connected into a polypeptide chain, the structure of which is previously stored in genetic code DNA (or RNA if bacterial biosynthesis is being considered). A protein is a strict sequence of amino acid residues. This is a chain ordered in a certain structure, performing a pre-programmed function in the cell.

Stage sequence of protein biosynthesis

The process of protein formation consists of a chain of stages: replication of a section of DNA (or RNA), synthesis of informational type RNA, its release into the cytoplasm of the cell from the nucleus, connection with the ribosome, and gradual attachment of amino acid residues that are supplied by transfer RNA. A substance that is a protein monomer participates in the enzymatic reaction of cleavage of a hydroxyl group and a hydrogen proton, and then joins the growing polypeptide chain.

Thus, a polypeptide chain is obtained, which, already in the cellular endoplasmic reticulum, is ordered into some predetermined structure and supplemented with a carbohydrate or lipid residue, if required. This is called the process of "maturation" of the protein, after which it is sent by the transport cellular system to its destination.

Functions of synthesized proteins

The monomers of proteins are the amino acids necessary to build their primary structure. The secondary, tertiary and quaternary structure is already formed by itself, although sometimes it also requires the participation of enzymes and other substances. However, they are no longer essential, although they are essential for proteins to perform their function.

An amino acid, which is a protein monomer, can have attachment sites for carbohydrates, metals, or vitamins. The formation of a tertiary or quaternary structure makes it possible to find even more places for the insertion groups. This allows you to create a protein derivative that plays the role of an enzyme, a receptor, a carrier of substances into or out of a cell, an immunoglobulin, a structural component of a membrane or a cell organelle, a muscle protein.

Proteins, formed from amino acids, are the only basis of life. And today it is believed that life just arose after the appearance of the amino acid and as a result of its polymerization. After all, it is the intermolecular interaction of proteins that is the beginning of life, including intelligent life. All other biochemical processes, including energy ones, are necessary for the implementation of protein biosynthesis, and as a result, the further continuation of life.

Option number 1

Task 1.

A fragment of one of the chains of the DNA molecule has the following nucleotide sequence:

…A-G-T-A-C-C-G-A-T-A-C-G-A-T-T-T-A-C-G…

What sequence of nucleotides does the second chain of the same molecule have?

Task number 2.

Find and correct the mistake in the chain of the DNA molecule.

A-A-G-T-C-A-T-T-U-T-U-A

G-T-C-A-U-U-A-A-A-A-A-A

Test.

1. Hydrophobic compounds are

1) enzymes
2) proteins
3) polysaccharides
4) lipids

Explanation.

Hydrophobic substances are insoluble in water, primarily fats.

(lipids)

Answer: 4

2. What substances are synthesized in human cells from amino acids

1) phospholipids
2) carbohydrates
3) vitamins
4) proteins

Explanation.

Proteins are synthesized from amino acids, carbohydrates consist of monosaccharides, phospholipids from glycerol and fatty acids, vitamins have a different nature.

The correct answer is numbered: 4

Answer: 4

3. Which monomers of molecules organic matter are amino acids

1) proteins
2) carbohydrates
3) DNA
4) lipids

Explanation.

Amino acids are part of proteins. Carbohydrates consist of monosaccharides, DNA from nucleotides, lipids from glycerol and fatty acids.

Answer: 1

4. The enzymatic function in the cell is performed

1) proteins
2) lipids
3) carbohydrates
4) nucleic acids

Explanation.

Lipids are part of the membrane and participate in the selective permeability of membranes, carbohydrates are used for oxidation and the formation of ATP molecules, nucleic acids store and transmit hereditary information, and proteins are part of enzymes, therefore, they perform an enzymatic function.

The correct answer is numbered: 1

Answer: 1

5. The synthesis of which simple organic substances in the laboratory confirmed the possibility of the abiogenic origin of proteins

1)amino acids
2) sugars
3) fat
4) fatty acids

Explanation.

Proteins are made up of amino acids. If amino acids can be created abiogenically, then proteins could be formed from them.

The correct answer is numbered: 1

Answer: 1

6. Ribose is part of the molecules

1) hemoglobin
2) DNA
3) RNA
4) chlorophyll

Explanation.

Ribose is a monosaccharide that is part of RNA.

Answer: 3

7. Name the molecule that is part of the cell and has carboxyl and amino groups.

1) Glucose
2) DNA
3) Amino acid
4) Fiber

Explanation.

The amino group and the carboxyl group contain amino acids in their composition.

The correct answer is numbered: 3

Answer: 3

8. Lipids are ether soluble but not water soluble

1) consist of monomers
2) hydrophobic
3) hydrophilic
4) are polymers

Explanation.

Hydrophobic substances do not dissolve in water, such substances are lipids.

Answer: 2

9. Hydrogen bonds between CO and NH groups in a protein molecule give it a helical shape characteristic of the structure

1) primary
2) secondary
3) tertiary
4) Quaternary

10. The helical secondary structure of a protein is held together by bonds

1) peptide
2) ionic
3) hydrogen
4) covalent

11. Water, which plays an important role in the entry of substances into the cell and the removal of waste products from it, performs the function

1) solvent
2) construction
3) catalytic
4) protective

1 Explanation.

Water is the best solvent in the cell.

The correct answer is numbered: 1

Answer: 1

12. A significant part of the contents of the cell is water, which

1) forms a division spindle
2) forms protein globules
3) dissolves fats
4) gives the cell elasticity

Explanation.

Water, filling the cell, gives it elasticity. The pressure of the cytoplasm acts on the cell wall. Fats are hydrophobic and do not dissolve in water. Protein globules are formed due to hydrogen bonds, disulfide bridges, ionic and hydrophobic interactions.

The correct answer is numbered: 4

Answer: 4

13. Living organisms need nitrogen because it serves

1) the main constituent of proteins and nucleic acids
2) the main source of energy
3) the main structural component of fats and carbohydrates
4) the main carrier of oxygen

14. Protein monomers are:

1) nucleotide

2) amino acid

3) glucose

4) glycerin

15. The sequence of monomers in a polymer is called:

1) primary structure

2) secondary structure

3) tertiary structure

4) quaternary structure

16. DNA is a polymer:

1) non-linear

2) linear

3) checkered

4) branched

17. Iron is included in:

1) hemoglobin

2) erythromycin

3) insulin

4) wood

Test on the topic " Chemical composition cells. Nucleic acids".

Option number 2

Task #1

Specify the order of nucleotides in the DNA chain formed by copying the chain:

C-A-C-C-G-T-A-A-C-G-G-A-T-C…

What is the length of the DNA chain and its mass? (The mass of one nucleotide is 345 c.u.)

Task #2

What is the molecular weight of a gene (two strands of DNA) if a protein with a molecular weight of 1500 c.u. is programmed in one of its strands?

Test.

1. Organic substances that accelerate metabolic processes -

1) amino acids
2) monosaccharides
3) enzymes
4) lipid

Explanation.

Enzymes are accelerators of processes in the cell.

The correct answer is numbered: 3

Answer: 3

2. ATP molecules perform a function in the cell

1) protective
2) catalytic
3)energy storage
4) transport of substances

Explanation.

ATP is an energy accumulator, the rest of the functions belong to proteins.

The correct answer is numbered: 3

Answer: 3

3. What bonds determine the primary structure of protein molecules

1) hydrophobic between amino acid radicals
2) hydrogen between polypeptide strands
3) peptide between amino acids
4) hydrogen between -NH- and -CO- groups

Explanation.

The primary structure of a protein is determined by the sequence of amino acids that are interconnected by peptide bonds.

The correct answer is numbered: 3

Answer: 3

4. The quaternary structure of a protein molecule is formed as a result of the interaction

1) sections of one protein molecule according to the type of S-S bonds
2) several polypeptide filaments forming a coil
3) sections of one protein molecule due to hydrogen bonds
4) protein globules with a cell membrane

Explanation.

The quaternary structure of a protein is the number and arrangement of polypeptide chains. Proteins consisting of one polypeptide chain have only a tertiary structure (lysozyme, pepsin, myoglobin, trypsin), they are called monomers. For proteins consisting of several polypeptide chains, a quaternary structure is characteristic.

The correct answer is numbered: 2

Answer: 2

5. In the cell, lipids perform the function

1) catalytic
2) transport
3) information
4) energyExplanation.

1, 2 - functions of proteins, 3 - function of DNA, 4 - function of lipids and carbohydrates.

The correct answer is numbered: 4

Answer: 4

6. In human and animal cells, as a building material and energy source,

1) hormones and vitamins
2) water and carbon dioxide
3) inorganic substances
4) proteins, fats and carbohydrates

Explanation.

Cell organelles are made up of proteins, fats and carbohydrates.

The correct answer is numbered: 4

Answer: 4

7. Fats, like glucose, perform a function in the cell

1) construction
2) information
3) catalytic
4) energy

Explanation.

A, C - functions of proteins, B - function of DNA, D - function of lipids and carbohydrates.

The correct answer is numbered: 4

Answer: 4

8. The secondary structure of a protein molecule has the form

1) spirals
2) double helix
3) ball
4) threads

Explanation.

The primary structure is linear, the secondary is a spiral, and the coil is a tertiary structure.

The correct answer is numbered: 1

Answer: 1

9. What is the function of proteins produced in the body when bacteria or viruses enter it?

1) regulatory
2) signal
3) protective
4) enzymatic

Explanation.

Lymphocytes produce antibodies, which are represented by proteins, so proteins perform a protective function in the body.

The correct answer is numbered: 3

Answer: 3

10. Molecules perform various functions in the cell

1) DNA
2) proteins
3) mRNA
4) ATP

11. Minerals in the body are NOT involved in

1) building a skeleton
2) release of energy due to biological oxidation
3) regulation of cardiac activity
4) maintaining acid-base balanceExplanation.

Energy is released when glucose is oxidized, minerals are involved in all other listed processes.

The correct answer is numbered: 2

Answer: 2

12. Water plays an important role in the life of the cell, as it

1) participates in many chemical reactions
2) provides normal acidity of the environment
3) speeds up chemical reactions
4) is part of the membranes

Explanation.

Water is a direct participant in many chemical processes in the cell. For example, it participates in the photolysis of water during photosynthesis.

The correct answer is numbered: 1

Answer: 1

13. Water is involved in heat regulation due to

1) polarity of molecules
2) low heat capacity
3) high heat capacity
4) small molecular sizes

14 .Guanine refers to the bases:

1) purine

2) pyrimidine

3) aniline

4) naphthalene

15. What is not part of DNA?

1) thymine

2) uracil

3) guanine

4) cytosine

16. Sucrose is:

1) polymer

2) monomer

3) dimer

4) cotton wool

17. Which of the following are polymers?

1) glucose

2) glycogen

3) cholesterol

4) DNA

5) hemoglobin

Test on the topic “Chemical composition of the cell. Nucleic acids".

Option number 3

Task 1.

known molecular weights four proteins:

A) 3000 USD; B) 4600 USD; B) 78000 c.u.; D) 3500 c.u.

Determine the lengths of the corresponding genes.

Task 2.

A fragment of a DNA molecule contains 2348 nucleotides, of which 420 are adenine. How many other nucleotides are there? Find the mass and length of the fragment and DNA?

1. Phospholipids are

1) enzymes responsible for the breakdown of fats
2) neurotransmitters synthesized by nerve cells
3) structural component cell membranes
4) storage substance of the cell

Explanation.

Phospholipids make up a double layer in the membrane, perform a structural function.

The correct answer is numbered: 3

Answer: 3

2. rRNA is

1) carrier genetic information
2) carrier of amino acids
3) component of the cell nucleus
4) ribosome component

Explanation.

mRNA is a carrier of genetic information, tRNA is a carrier of amino acids, DNA is a component of the nucleus, rRNA is a component of ribosomes.

The correct answer is numbered: 4

Answer: 4

3. A peptide bond is formed between

1) amino acids
2) glucose residues
3) water molecules
4) nucleotides

Explanation.

A peptide bond occurs between amino acids - that is, it occurs during the formation of proteins and peptides as a result of the interaction of the α-amino group (-NH2) of one amino acid with the α-carboxyl group (-COOH) of other amino acids

Between glucose residues, and between nucleotides - a polar covalent bond.

Hydrogen bonds form between water molecules. This chemical bond- intermolecular.

The correct answer is numbered: 1

Answer: 1

4. How many hydrogen bonds bind adenine to thymine in a DNA molecule?

1) 1
2) 2
3) 3
4) 4

Explanation.

Hydrogen bonds between the nucleotides of two DNA chains: adenine-thymine (A-T) - double; guanine-cytosine (G-C) - triple.

The correct answer is numbered: 2

Answer: 2

5. Signaling, motor, transport and protective functions in the cell are performed by

1) proteins
2) carbohydrates
3) lipids
4) DNA

Explanation.

The functions of proteins are varied.

- Building material - proteins are involved in the formation of the cell membrane, organelles and cell membranes. Blood vessels, tendons, and hair are built from proteins.

- Catalytic role - all cellular catalysts are proteins (active sites of the enzyme). The structure of the active site of the enzyme and the structure of the substrate exactly match each other, like a key and a lock.

- Motor function - contractile proteins cause any movement.

- Transport function - blood protein hemoglobin attaches oxygen and carries it to all tissues.

- The protective role is the production of protein bodies and antibodies to neutralize foreign substances.

- Energy function - 1 g of protein is equivalent to 17.6 kJ.

And if separately some of the listed functions can be inherent in both lipids and carbohydrates, then together - only proteins.

The correct answer is numbered: 1

Answer: 1

6. The secondary structure of the protein is maintained

1) covalent bonds
2) electrostatic interactions
3) hydrogen bonds
4) hydrophobic interactions

Explanation.

Secondary structure - local ordering of a fragment of a polypeptide chain, stabilized by hydrogen bonds.

The correct answer is numbered: 3

Answer: 3

7. Energy-rich bonds between phosphoric acid residues are present in the molecule

1) ATP
2) DNA
3) mRNA
4) squirrel

Explanation.

ATP - these bonds are called macroenergetic, because. when they break, 40 kJ of energy is released. ATP is adenosine phosphoric acid containing 3 phosphoric acid residues (or phosphate residues), serves as a universal carrier and the main accumulator of chemical energy in living cells

The correct answer is numbered: 1

Answer: 1

8. During photosynthesis, light energy is used to synthesize molecules

1) DNA
2) proteins
3) fat
4) ATP

Explanation.

During the light phase, a quantum of light is absorbed by chlorophyll, resulting in the formation of ATP and NADPH molecules. Water breaks down, forming hydrogen ions and releasing an oxygen molecule.

The correct answer is numbered: 4

Answer: 4

9. Proteins of the outer plasma membrane provide

1) transport of substances into the cell
2) oxidation of substances
3) its full permeability
4) elasticity and turgor of the cell

Explanation.

The main functions of the cell membrane (plasmalemma) are the following: 1) barrier, 2) receptor, 3) exchange, 4) transport.

The membrane provides selective penetration into the cell and from the cell to environment various chemicals. There are two main ways of substances entering the cell and leaving the cell to the external environment: passive transport, active transport.

With facilitated diffusion, proteins are involved in the transport of substances - carriers that work according to the "ping-pong" principle. In this case, the protein exists in two conformational states: in the “pong” state, the binding sites of the transported substance are open on the outside of the bilayer, and in the “ping” state, the same sites open on the other side. This process is reversible. From which side of this moment The time the binding site of a substance will be opened depends on the concentration gradient of this substance.

In this way, sugars and amino acids pass through the membrane.

The correct answer is numbered: 1

Answer: 1

10. Enzymatic, building, transport, protective functions in the cell are performed by molecules

1) lipids
2) carbohydrates
3) DNA
4) proteins

11. What kind of ions chemical element necessary for the blood clotting process?

1) sodium
2) magnesium
3) iron
4) calcium

12. In the process of blood clotting, one of the factors is calcium.

The correct answer is numbered: 4

Answer: 4

What property of water makes it a good solvent in biological systems?

1) high thermal conductivity
2) slow heating and cooling
3) high heat capacity
4) polarity of molecules

13. Explanation.

The water molecule is dipole, so it is a good solvent.

The correct answer is numbered: 4

Answer: 4

One of the elements that determine active ion transport across cell membranes is

1) potassium
2) phosphorus
3) iron
4) nitrogen

14. DNA does not include:

1) deoxyribose

2) adenine

3) uracil

4) phosphate

15 .From the following substances, select polymers:

1) glucose

2) cellulose

3) cholesterol

4) RNA

5) hemoglobin

16. How many types of amino acids are in a protein?

1) 12

2) 25

3) 20

4) as much as you like

17 .Proteins that make up chromosomes are called:

1) histones

2) protons

3) chromatins

4) Pinocchio

Answers to the test "The chemical composition of the cell. Nucleic acids » .

№ test

Option number 1

Option number 2

1,3

Option number 3

2,4,5

55. What substances are synthesized in human cells from amino acids
A) phospholipids B) carbohydrates C) vitamins D) proteins

81. The monomers of the molecules of which organic substances are amino acids
A) proteins B) carbohydrates C) DNA D) lipids

109. At the heart of education peptide bonds between amino acids in a protein molecule lies
A) the principle of complementarity
B) insolubility of amino acids in water
C) the solubility of amino acids in water
D) the presence of carboxyl and amine groups in them

163. Enzymatic function in the cell is performed
A) proteins
B) lipids
B) carbohydrates
D) nucleic acids

250. The synthesis of what simple organic substances in the laboratory confirmed the possibility of the abiogenic origin of proteins
A) amino acids
B) sugars
B) fat
D) fatty acids

364. Name a molecule that is a part of a cell and has carboxyl and amino groups
A) glucose
B) DNA
B) amino acid
D) fiber

439. Hydrogen bonds between CO and NH groups in a protein molecule give it a helical shape characteristic of the structure
A) primary
B) secondary
B) tertiary
D) quaternary

490. The secondary structure of a protein, having the shape of a spiral, is held by bonds
A) peptide
B) ionic
B) hydrogen
D) covalent

550. Organic substances accelerating metabolic processes -
A) amino acids
B) monosaccharides
B) enzymes
D) lipids

945. What bonds determine the primary structure of protein molecules
A) hydrophobic between amino acid radicals
B) hydrogen between polypeptide strands
C) peptide between amino acids
D) hydrogen between -NH- and -CO- groups

984. The process of denaturation of a protein molecule is reversible if bonds are not broken
A) hydrogen
B) peptide
B) hydrophobic
D) disulfide

1075. The quaternary structure of a protein molecule is formed as a result of interaction
A) sections of one protein molecule according to the type of S-S bonds
B) several polypeptide filaments forming a ball
C) sections of one protein molecule due to hydrogen bonds
D) protein globules with a cell membrane

1290. The secondary structure of a protein molecule has the form
A) spirals
B) double helix
B) ball
D) threads

1291. What is the function of proteins produced in the body when bacteria or viruses penetrate into it
A) regulatory
B) signal
B) protective
D) enzymatic

1293. What is the function of proteins accelerating chemical reactions in the cell
A) hormonal
B) signal
B) enzymatic
D) information

1312. Accelerate chemical reactions in the cell
A) enzymes
B) pigments
B) vitamins
D) hormones

2063. The primary structure of a protein is formed by a bond
A) hydrogen
B) macroergic
B) peptide
D) ionic

2065. The main function of enzymes in the body
A) catalytic
B) protective
B) storage
D) transport

2088. By their nature, enzymes are
A) nucleic acids
B) proteins
B) lipids
D) carbohydrates

2144. The destruction of the structure of a protein molecule is
A) denaturation
B) broadcast
B) reduplication
D) renaturation

2367. Speed chemical reactions change the proteins in the cell that perform the function
A) a signal
B) humoral
B) catalytic
D) information

2420. Biocatalysts of chemical reactions in the human body are
A) hormones
B) carbohydrates
B) enzymes
D) vitamins

2483. Protective function in the body is performed by proteins that
A) carry out immune responses
B) able to contract
B) transport oxygen
D) speed up metabolic reactions

2504. The sequence and number of amino acids in a polypeptide chain is
A) the primary structure of DNA
B) the primary structure of the protein
C) secondary structure of DNA
D) secondary structure of the protein

2562. Enzymatic, building, transport, protective functions in the cell are performed by molecules
A) lipids
B) carbohydrates
B) DNA
D) proteins