Unified State Exam test the chemical composition of a cell. Cell theory, chemical composition, structure, functions

Biology test to test the knowledge of students in grades 9-11 on the topic:

"CHEMICAL COMPOSITION OF THE CELL"

Select 1 correct answer:

A1. A molecule is made up of amino acids

1) squirrel

2) DNA

3) RNA

4) starch

A2. The greatest amount of energy is released during decomposition

1) proteins

2) fats

3) carbohydrates

4) nucleic acids

A3. The following polymers are made up of nucleotides

1) proteins

2) fats

3) DNA and RNA

4) polysaccharides

A4. Amino acids are monomers

1) glycogen and starch

2) proteins

3) nucleic acids

4) lipids

A5. The cell membrane consists of

1) protein and carbohydrates

2) carbohydrates and lipids

3) protein and nucleic acids

4) protein, lipids and carbohydrates

A6. The universal source of energy in the cell is

1) uracil

2) ATP

3) amino acids

4) RNA

A7. The cell wall of plant cells is predominantly composed of

1) sucrose

2) glycogen

3) squirrel

4) cellulose

A8. The carrier of genetic information in a cell is a molecule

1) mureina

2) squirrel

3) RNA

4) DNA

A9. Proteins include

1) 20 different amino acids

2) 40 different amino acids

3) 20 different nucleotides

4) 20 different monosaccharides

A10. In the human body, proteins are used as a source of energy if

1) they come from food in large quantities

2) they are formed in the body itself in large quantities

3) all reserves of carbohydrates and fats have been used up

4) the body does not need energy

A11. DNA molecule as opposed to RNA molecule

1) consists of 2 nucleotides

2) consists of protein

3) consists of 2 polynucleotide chains

4) not found in wildlife

A12. A gene is a section of a molecule

1) RNA

2) DNA

3) squirrel

4) lipid

A13. Viruses are made up of

1) lipid membrane, DNA or RNA molecules

2) protein shell, DNA and RNA molecules

3) chitin shell, proteins and ATP molecules

4) polysaccharide shell and RNA molecules

A14. When 1 gram of fat is completely broken down, it forms

1) 17.2 kJ energy

2) 14.6 kJ energy

3) 39.1 kJ energy

4) 42.3 kJ energy

A15. How many amino acids are involved in protein synthesis?

1) 10

2) 20

3) 30

4) 46

A16. Simple carbohydrates are called

1) oligosaccharides

2) disaccharides

3) monosaccharides

4) polysaccharides

A17. A polysaccharide in a plant cell is

1) protein

2) starch

3) nucleic acid

4) glucose

A18. The greatest danger to human health is the lack of

1) fats

2) proteins

3) carbohydrates

4) lipids

A19. DNA is a biological polymer whose monomers are

1) amino acid

2) monosaccharide

3) nucleotide

4) nitrogenous base

A20. The tRNA monomer is

1) amino acid

2) protein

3) nucleotide

4) polysaccharide

A21. Ribosomes contain

1) i-RNA, r-RNA and DNA

2) r-RNA and proteins

3) tRNA and DNA section

4) DNA section and proteins

A22. In accordance with the principle of complementarity, adenine in a DNA molecule forms a pair with

1) cytosine

2) thymine

3) guanine

4) uracil

Answers to test questions:

Question

answer

Question

answer

Question

Answer

1

1

11

3

21

2

2

2

12

2

22

2

3

3

13

2

4

2

14

3

5

4

15

2

6

2

16

3

7

4

17

2

8

4

18

2

9

1

19

3

10

3

20

3

Unified State Exam training tests. Biology. Topic: chemical composition of the cell.

1 . Living organisms need nitrogen because it serves

1. integral component of proteins and nucleic acids 2. main source of energy 3. structural component of fats and carbohydrates 4. main oxygen carrier

2 . Water plays an important role in the life of a cell, as it 1. participates in many chemical reactions 2 ensures normal acidity of the environment 3 accelerates chemical reactions

4.part of membranes

3 . The main source of energy in the body is:

1) vitamins 2. enzymes 3 hormones 4 carbohydrates

4organic substances in the cell move to organoids along

1. vacuole system 2. lysosomes 3. mitochondria 4. endoplasmic reticulum

4. The cells of which organisms contain tens of times more carbohydrates than animal cells?

1 saprotrophic bacteria 2. unicellular 3. protozoa 4. plants

5. In cells, lipids perform the function

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

6. In human and animal cells, they are used as a building material and source of energy.

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

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

1) construction 2. information 3. catalytic 4 energy

8 . Indicate which number in the figure indicates the secondary structure of the protein molecule

9. The enzymes include

1 nucleic acids 2. proteins 3. ATP molecules 4. carbohydrates

10. The quaternary structure of protein molecules is formed as a result of interaction

1. amino acids and peptide bond formation 2. several polypeptide strands 3. sections of one protein molecule due to hydrogen bonds 4. protein globule with cell membrane

11. What is the function of proteins produced in the body when bacteria or viruses penetrate it? 1) regulatory 2. signaling 3. protective 4. enzymatic

1 2. Molecules perform various functions in the cell.
1) DNA 2) proteins 3) mRNA 4) ATP

13. What is the function of proteins that accelerate chemical reactions in a cell?

1) hormonal 2) signaling 3. enzymatic 4. informational

1 4. The program about the primary structure of protein molecules is encrypted in molecules

1) tRNA 2) DNA 3) lipids 4) polysaccharides

1 5. In a DNA molecule, two polynucleotide strands are linked by

1 complementary nitrogenous bases 2 phosphoric acid residues 3. amino acids 4. carbohydrates

16 The bond that occurs between the nitrogenous bases of two complementary DNA strands is

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

1 7. Due to the ability of DNA molecules to reproduce their own kind,

1 the organism’s adaptation to its environment is formed

2. modifications occur in individuals of the species 3. new combinations of genes appear

4. hereditary information is transmitted from the mother cell to the daughter cells

18. DNA molecules represent the material basis of heredity, since they encode information about the structure of molecules 1. polysaccharides

2. proteins 3) lipids 4) amino acids

19. There are 100 nucleotides in a DNA molecule with thymine, which is 10% of the total. How many nucleotides are there with guanine?

2)400

1)200

3)1000

4)1800

20. Hereditary information about the characteristics of an organism is concentrated in molecules

1. tRNA 2. DNA 3. protein 4. polysaccharides

21. Ribonucleic acids in cells are involved in

1. storage of hereditary information 2 biosynthesis of proteins

3. biosynthesis of carbohydrates 4. regulation of fat metabolism

22. mRNA molecules, unlike tRNA,

1serve as a matrix for protein synthesis 2serve as a matrix for tRNA synthesis

3. deliver amino acids to the ribosome 4. transfer enzymes to the ribosome

23. The mRNA molecule transmits hereditary information

1.from the nucleus to the mitochondrion 2.from one cell to another

3. from the nucleus to the ribosome 4. from parents to offspring

24. RNA molecules, unlike DNA, contain a nitrogen base

1) adenine 2) guanine 3uracil cytosine

25. Ribose, unlike deoxyribose, is part of1) DNA 2) mRNA 3) proteins 4) polysaccharides

26. The process of denaturation of a protein molecule is reversible if connections are not broken

1) hydrogen 2. peptide 3. hydrophobic 4. disulfide

27. ATP is formed during the process 1. protein synthesis on ribosomes

2.decomposition of starch to form glucose

3. oxidation of organic substances in the cell 4. phagocytosis

28The monomer of a protein molecule is

1) nitrogenous base 2) monosaccharide 3) amino acid 4) lipids

29Most enzymes are

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

30The building function of carbohydrates is that they

1) form a cellulose cell wall in plants2) are biopolymers

3) able to dissolve in water4) serve as a reserve substance for the animal cell

31Lipids play an important role in the life of a cell, since they1) are enzymes

2) dissolve in water 3) serve as a source of energy4) maintain a constant environment in the cell

32Protein synthesis in eukaryotes occurs: a. on ribosomes b. on ribosomes in the cytoplasm

B. on the cell membrane D. on microfilaments in the cytoplasm.

33. Primary, secondary and tertiary structures of a molecule are characteristic of:

1.glycogen 2.adenine 3.amino acids 4.DNA.

Part B

1.The RNA molecule contains

A) ribose B) guanine C) magnesium cation D) deoxyriboseD) amino acid E) phosphoric acid

Write the answer as a sequence of letters in alphabetical order (without spaces or other symbols).

2. Establish a correspondence between the function of the compound and the biopolymer for which it is characteristic. In the table below, under each number that defines the position of the first column, write down the letter corresponding to the position of the second column.

FUNCTION

1) storage of hereditaryinformation BIOPOLYMER A) protein B) DNA

2) formation of new moleculesby self-doubling

3) acceleration of chemical reactions

4) is an obligatory component of the cell membrane

5) neutralization of antigens

3. Establish a correspondence between the function of the compound and the biopolymer for which it is characteristic. In the table below, under each number that defines the position of the first column, write down the letter corresponding to the position of the second column.

FUNCTION

1) formation of cell walls BIOPOLYMER A) polysaccharide B) nucleic acid

2) transport of amino acids

3) storage of hereditary information

4) serves as a reserve nutrient

5) provides the cell with energy

Write down the resulting sequence of letters in the table and transfer it to the answer form (without spaces or other symbols).

Part C

1 .In one chain of a DNA molecule there are 31% adenyl residues, 25% thymidyl residues and 19% cytidyl residues. Calculate the percentage of nucleotides in double-stranded DNA.

2. Find errors in the given text, correct them, indicate the numbers of the sentences in which they are made, write down these sentences without errors.

1. Proteins are biological polymers, 2. The mo numbers of proteins are amino acids. 3. Proteins contain 30 equal amino acids. 4. All amino acids can be synthesized in the human and animal bodies. 5. Amino acids are connected in a protein molecule by non-covalent peptide bonds.

3. The content of nucleotides in the mRNA chain is as follows: A-35%, G-27%, C-18%, U-20%. Determine the percentage composition of nucleotides in a section of a 2-stranded DNA molecule that is the template for this mRNA.

4. How many ATP molecules will be synthesized in eukaryotic cells during the complete oxidation of a fragment of a starch molecule consisting of 10 glucose residues?

5 .What is the role of proteins in the body?

6. Find errors in the given text. Specify numbers of the sentences in which they are made. Explain them.1. Everyone presentIn the body proteins are enzymes.

2. Each enzyme accelerates the flow of several chemicalreactions. 3. The active center of the enzyme strictly corresponds to the configuration of the substrate with which it interacts. 4. Enzyme activity does not depend on factors such as temperature, pH, and other factors. 7. Find errors in the given text. Indicate the numbers of the previous ones in which they are admitted, explain them.

1. Messenger RNA is synthesized on a DNA molecule.2. Its length does not depend on the volume of information being copied.3. The amount of mRNA in the cell is 85% of the total amount in the cell.

4. There are three types of tRNA in the cell.5. Each tRNA attaches a specific amino acid and transports it to the ribosomes.6. In eukaryotes, tRNA is much longer than mRNA.

8 Indicate the numbers of sentences in which errors were made. Explain them.

1. Hydrocarbons are compounds of carbon and hydrogen

2. There are three main classes of carbohydrates - monosaccharides, saccharides and polysaccharides.

3. The most common monosaccharides are sucrose and lactose.

4. They are water soluble and have a sweet taste.

5. When 1 g of glucose is broken down, 35.2 kJ of energy is released

9 . What are the similarities and differences between RNA, DNA, ATP?

10 Why doesn't glucose play a storage role in the cell?

Write a short answer containing at least two elements on the back of the form or on a separate sheet of paper.

11 Why is starch classified as a biopolymer and what property of starch determines its storage function in the cell?

Answers to the Unified State Exam on the topic “Chemical composition of the cell”

Part B.

1ABE 2.BBAAA 3ABBAA

Part C

1.A-31% T-25% C-19% Total 65%, so 100-65=25% (guanine)

in accordance with the principle of complementarity

A=T=31+25=56% i.e. 28% each

G=C=19+25=44% i.e. 22% each

2. 345

3. In accordance with the principle of complementarity, the following nucleotides are found in 1 strand of DNA, which is the template for the synthesis of mRNA

T35% C27% G18% A20%

A=T=35+20=55% i.e. 27.5% each

C=G=27+18=45% i.e. 25.5% each

4. In the process of cellular respiration, the oxidation of 1 molecule of glucose produces 38 molecules of ATP. A fragment of a starch molecule hydrolyzes up to 10 glucose residues, each of which undergoes complete oxidation, resulting in the formation of 380 ATP molecules.

5. Enzymatic, regulatory, structural, signaling, protective, motor, transport, energy.

6.124

7. errors 2-depends, 3-5%, 4-about 40 types, 6-shorter (70-90 nucleotides)

8. errors 1-carbohydrates and water 3-disaccharides 5-17.6 kJ

10. Glucose, a hydrophilic compound, enters into metabolism in an aquatic environment and cannot accumulate.

11. Starch is a polysaccharide, monomer – glucose. Starch has the property of being hydrophobic, so it can accumulate in the cell.

Carbohydrates, or saccharides, are one of the main groups of organic compounds. They are part of the cells of all living organisms. The main function of carbohydrates is energy (during the breakdown and oxidation of carbohydrate molecules, energy is released, which ensures the vital functions of the body). When there is an excess of carbohydrates, they accumulate in the cell as reserve substances (starch, glycogen) and, if necessary, are used by the body as a source of energy. Carbohydrates are also used as a building material.

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Chemical composition of the cell

(preparation for the Unified State Exam)

Carbohydrates, or saccharides, are one of the main groups of organic compounds. They are part of the cells of all living organisms.

The main function of carbohydrates is energy (during the breakdown and oxidation of carbohydrate molecules, energy is released, which ensures the vital functions of the body). When there is an excess of carbohydrates, they accumulate in the cell as reserve substances (starch, glycogen) and, if necessary, are used by the body as a source of energy. Carbohydrates are also used as a building material.

General formula of carbohydrates

Cn(H2O)m

Carbohydrates are made up of carbon, hydrogen and oxygen.

Carbohydrate derivatives may also contain other elements.

Water-soluble carbohydrates.Monosaccharides and disaccharides

Example:

Of the monosaccharides, the most important for living organisms are ribose, deoxyribose, glucose, fructose, and galactose.

Glucose is the main source of energy for cellular respiration.

Fructose is a component of flower nectar and fruit juices.

Ribose and deoxyribose are structural elements of nucleotides, which are monomers of nucleic acids (RNA and DNA).
Disaccharides are formed by combining two monosaccharide molecules and are similar in properties to monosaccharides. For example, both are highly soluble in water and have a sweet taste.

Example:

Sucrose (cane sugar), maltose (malt sugar), lactose (milk sugar) are disaccharides formed by the fusion of two monosaccharide molecules:

Sucrose (glucose + fructose) is the main product of photosynthesis transported in plants.

Lactose (glucose + galactose) - is part of the milk of mammals.

Maltose (glucose + glucose) is a source of energy in germinating seeds.

Functions of soluble carbohydrates: transport, protective, signaling, energy.

Water-insoluble polysaccharides

Polysaccharides consist of a large number of monosaccharides. With an increase in the number of monomers, the solubility of polysaccharides decreases and the sweet taste disappears.

Example:

Polymeric carbohydrates: starch, glycogen, cellulose, chitin.

Functions of polymer carbohydrates: structural, storage, energy, protective.
Starch consists of branched spiral molecules that form reserve substances in plant tissues.

Cellulose is an important structural component of the cell walls of fungi and plants.

Cellulose is insoluble in water and has high strength.

Chitin consists of amino derivatives of glucose and is part of the cell walls of some fungi and forms the exoskeleton of arthropods.
Glycogen - reserve substance of an animal cell.

Complex polysaccharides are also known to perform structural functions in the supporting tissues of animals (they are part of the intercellular substance of skin, tendons, and cartilage, giving them strength and elasticity).

Lipids - an extensive group of fat-like substances (esters of fatty acids and trihydric alcohol glycerol), insoluble in water. Lipids include fats, waxes, phospholipids and steroids (lipids that do not contain fatty acids).

Lipids are made up of hydrogen, oxygen and carbon atoms.

Lipids are present in all cells without exception, but their content in different cells varies greatly (from 2-3 to 50-90%).

Lipids can form complex compounds with substances of other classes, for example, with proteins (lipoproteins) and carbohydrates (glycolipids).

Functions of lipids:

• Storage - fats are the main form of lipid storage in the cell.
• Energy - half of the energy consumed by the cells of vertebrates at rest is formed as a result of the oxidation of fats (when oxidized, they provide more than twice as much energy as carbohydrates).
• Fats are used and how water source (with the oxidation of 1 g of fat, more than 1 g of water is formed).
• Protective - the subcutaneous fat layer protects the body from mechanical damage.
• Structural - phospholipids are part of cell membranes.
• Thermal insulation- subcutaneous fat helps retain heat.
• Electrical insulating- myelin, secreted by Schwann cells (form the sheaths of nerve fibers), insulates some neurons, which greatly accelerates the transmission of nerve impulses.
• Hormonal (regulatory) ) - adrenal hormone - cortisone and sex hormones (progesterone and testosterone) are steroids ().
• Lubricating - waxes cover the skin, wool, feathers and protect them from water. The leaves of many plants are covered with a waxy coating; wax is used in the construction of honeycombs.

Proteins (proteins, polypeptides ) are the most numerous, most diverse and of paramount importance biopolymers. Protein molecules contain atoms of carbon, oxygen, hydrogen, nitrogen and sometimes sulfur, phosphorus and iron.

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

Thanks to this, amino acids can connect with each other (their number in one molecule can reach several hundred). In this regard, protein molecules are large in size and are calledmacromolecules.

Structure of a protein molecule

The structure of a protein molecule is understood as its amino acid composition, the sequence of monomers and the degree of twist of the protein molecule.

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

• The sequence of amino acids in a polypeptide chain isprotein primary structure(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 on the appearance 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 isprotein secondary structure.
• Protein tertiary structure- three-dimensional spatial “packaging” of the polypeptide chain in the form globules (ball). The strength of the tertiary structure is ensured by a variety of bonds that arise between amino acid radicals (hydrophobic, hydrogen, ionic and disulfide S-S bonds).
• Some proteins (for example, human hemoglobin) havequaternary 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 weak ionic, hydrogen and hydrophobic bonds.

The structure of proteins can be disrupted (subjected to denaturation ) when heated, treated with certain chemicals, irradiated, etc. With weak exposure, only the quaternary structure disintegrates, with stronger exposure, 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.

Disruption of 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) etc.

Functions of proteins

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

• Structural (construction) function- one of the main functions of proteins (proteins are part of cell membranes; keratin protein forms hair and nails; collagen and elastin proteins form 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. Reception of signals from the external environment and transmission of information into the cell occurs due to proteins built into the membrane that are capable of changing their tertiary structure in response to the action of environmental factors.
• Contractile (motor) function- is provided by contractile proteins - actin and myosin (thanks to contractile proteins, cilia and flagella move in protozoa, chromosomes move during cell division, muscles contract in multicellular organisms, and other types of movement in living organisms are improved.

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

• Regulatory functioninherent 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 processes (for example, insulin regulates blood sugar).
• Energy function- during prolonged fasting, proteins can be used as an additional source of energy after carbohydrates and fats have been consumed (with the complete breakdown of 1 g of protein into final products, 17.6 kJ of energy is released). Amino acids released when protein molecules are broken down are used to build new proteins.

Nucleic acids(from the Latin nucleus - nucleus) were first discovered in 1868 in the nuclei of leukocytes by the Swiss scientist F. Miescher. Later it was found that nucleic acids are contained in all cells (in the cytoplasm, nucleus and all organelles of the cell).

Primary structure of nucleic acid molecules

Nucleic acids are the largest molecules formed by living organisms. They are biopolymers consisting of monomers - nucleotides

Pay attention!

Each nucleotide consists ofnitrogenous base, five-carbon sugar (pentose) And phosphate group (phosphoric acid residue).

Depending on the type of five-carbon sugar (pentose), two types of nucleic acids are distinguished:

• deoxyribonucleic acids(abbreviated DNA) - the DNA molecule contains a five-carbon sugar - deoxyribose.
• ribonucleic acids(abbreviated as RNA) - the RNA molecule contains a five-carbon sugar - ribose.

There are also differences in the nitrogenous bases that make up the nucleotides of DNA and RNA:

DNA nucleotides T - thymine
RNA nucleotides : A - adenine, G - guanine, C - cytosine, U - uracil

Secondary structure of DNA and RNA molecules

Secondary structure is the shape of nucleic acid molecules.

The spatial structure of the DNA molecule was modeled by American scientists James Watson and Francis Crick in 1953.

Deoxyribonucleic acid (DNA)- consists of two helically twisted chains, which are connected to each other along the entire length by hydrogen bonds. This structure (typical only of DNA molecules) is calleddouble helix.

Ribonucleic acid (RNA)- linear polymer consisting of one chain of nucleotides.

The exception is viruses that contain single-stranded DNA and double-stranded RNA.

More information about DNA and RNA will be discussed in the section “Storage and transmission of genetic information. Genetic code.”

Adenosine triphosphoric acid – ATP

Nucleotides are the structural basis for a number of organic substances important for life, for example, high-energy compounds.
The universal source of energy in all cells is ATP - adenosine triphosphoric acid or adenosine triphosphate.
ATP found in the cytoplasm, mitochondria, plastids and cell nuclei and is the most common and universal source of energy for most biochemical reactions occurring in the cell.
ATP provides energy for all cell functions: mechanical work, biosynthesis of substances, division, etc. Average content ATP in a cell is about 0.05% of its mass, but in those cells where costs ATP are large (for example, in liver cells, striated muscles), its content can reach up to 0.5%.

ATP structure

ATP is a nucleotide consisting of a nitrogenous base - adenine, the carbohydrate ribose and three phosphoric acid residues, two of which store a large amount of energy.

The bond between phosphoric acid residues is calledmacroergic(it is designated by the symbol ~), since when it breaks, almost 4 times more energy is released than when other chemical bonds are split.

ATP - unstable structure even when separating one phosphoric acid residue, ATP turns into adenosine diphosphate ( ADF ) releasing 40 kJ of energy.

Other nucleotide derivatives

A special group of nucleotide derivatives are hydrogen carriers. Molecular and atomic hydrogen is highly chemically active and is released or absorbed during various biochemical processes. One of the most widespread hydrogen carriers isnicotinamide dinucleotide phosphate(NADP).

NADP molecule capable of attaching two atoms or one molecule of free hydrogen, transforming into a reduced form NADP ⋅ H2 . In this form, hydrogen can be used in various biochemical reactions.
Nucleotides can also take part in the regulation of oxidative processes in the cell.

Vitamins

Vitamins (from lat. vita - life) - complex bioorganic compounds that are absolutely necessary in small quantities for the normal functioning of living organisms. Vitamins differ from other organic substances in that they are not used as a source of energy or building material. Organisms can synthesize some vitamins themselves (for example, bacteria are able to synthesize almost all vitamins); other vitamins enter the body with food.
Vitamins are usually designated by letters of the Latin alphabet. The modern classification of vitamins is based on their ability to dissolve in water and fats (they are divided into two groups:water-soluble(B 1, B 2, B 5, B 6, B 12, PP, C) and fat-soluble(A, D, E, K )).
Vitamins are involved in almost all biochemical and physiological processes that together make up metabolism. Both deficiency and excess of vitamins can lead to serious disturbances in many physiological functions in the body.

Minerals in the cell are in the form of salts in a solid state, or dissociated into ions.
Inorganic ions represented by cations and anions mineral salts.

Example:

Cations: K +, Na +, Ca 2+, Mg 2+, NH +4

Anions: Cl −, H 2 PO −4, HPO 2−4, HCO −3, NO −3, SO −4, PO 3−4, CO 2−3

Together with soluble organic compounds, inorganic ions provide stable performanceosmotic pressure.

The concentration of cations and anions in the cell and in its environment is different. Cations predominate inside the cell K + and large negative organic ions, there are always more ions in the pericellular fluids Na+ and Cl −. As a result,potential differencebetween the contents of the cell and its environment, providing such important processes as irritability and transmission of excitation along a nerve or muscle.

As components of the body's buffer systems, ions determine their properties - the ability to maintain pH at a constant level (close to a neutral reaction), despite the fact that acidic and alkaline products are continuously formed during the metabolic process.

Example:

Anions phosphoric acid(HPO 2−4 and H 2 PO −4) create a mammalian phosphate buffer system that maintains the pH of the intracellular fluid within the range of 6.9 - 7.4.
Carbonic acid and its anions(H 2 CO 3 and NO −3) create a bicarbonate buffer system and maintain the pH of the extracellular environment (blood plasma) at a level of 7.4.

Compounds of nitrogen, phosphorus, calcium and other inorganic substances are used for the synthesis of organic molecules (amino acids, proteins, nucleic acids, etc.).

Example:

Ions of some metals (Mg, Ca, Fe, Zn, Cu, Mn, Mo, Br, Co) are components of many enzymes, hormones and vitamins or activate them.

Potassium - ensures the functioning of cell membranes, maintains acid-base balance, affects the activity and concentration of magnesium.

Na+ and K ions + promote the conduction of nerve impulses and cell excitability. These ions are also part of the sodium-potassium pump (active transport) and create the transmembrane potential of cells (provides selective permeability of the cell membrane, which is achieved due to the difference in ion concentrations Na+ and K +: more inside the cell K +, more outside Na+).

Ions play a key role in the regulation of muscle contraction calcium (Ca 2+). Myofibrils have the ability to interact with ATP and contract only in the presence of certain concentrations of calcium ions in the environment. Calcium ions are also necessary for the blood clotting process.

Iron is part of blood hemoglobin.

Nitrogen is part of proteins. All the most important parts of cells (cytoplasm, nucleus, membrane, etc.) are built from protein molecules.

Phosphorus is part of nucleic acids; ensuring normal growth of bone and dental tissues.

With a lack of minerals, the most important vital processes of the cell are disrupted.

Test

1. Select examples of the functions proteins perform at the cellular level of life.

1) provide transport of ions across the membrane

2) are part of hair, feathers

3) form the skin

4) antibodies bind antigens

5) store oxygen in muscles

6) ensure the operation of the fission spindle

2. Select RNA features.

1) found in ribosomes and the nucleolus

2) capable of replication

3) consists of one chain

4) contained in chromosomes

5) set of ATGC nucleotides

6) set of nucleotides AGCU

3. What functions do lipids perform in the animal body?

1) enzymatic

2) storing

3) energy

4) structural

5) contractile

6) receptor

4. What functions do carbohydrates perform in the animal body?

1) catalytic

2) structural

3) storing

4) hormonal

5) contractile

6) energy

5. Proteins, unlike nucleic acids,

1) participate in the formation of the plasma membrane

2) are part of chromosomes

3) participate in humoral regulation

4) carry out a transport function

5) perform a protective function

6) transfer hereditary information from the nucleus to the ribosome

6 Which of the following proteins cannot be detected inside a muscle cell?

1) actin

2) hemoglobin

3) fibrinogen

4) ATPase

5) RNA polymerase

6) trypsin

7. Select the structural features of protein molecules.

1) consist of fatty acids

2) consist of amino acids

3) the monomers of the molecule are held together by peptide bonds

4) consist of monomers of the same structure

5) are polyhydric alcohols

6) the quaternary structure of molecules consists of several globules

8. Select three functions that are unique to proteins.

1) energy

2) catalytic

3) motor

4) transport

5) structural

6) storage

9. All of the chemical elements listed below, except two, are organogens. Identify two characteristics that “drop out” from the general list, and write down the numbers under which they are indicated in your answer.

1) hydrogen

2) nitrogen

3) magnesium

4) chlorine

5) oxygen

10 . Select THREE functions of DNA in a cell

1) an intermediary in the transfer of hereditary information

2) storage of hereditary information

3) coding of amino acids

4) matrix for mRNA synthesis

5) regulatory

6) chromosome structuring

11 DNA molecule

1) a polymer whose monomer is a nucleotide

2) a polymer whose monomer is an amino acid

3) double-chain polymer

4) single chain polymer

5) contains hereditary information

6) performs an energy function in the cell

12. What features are characteristic of a DNA molecule?

1) consists of one polypeptide strand

2) consists of two polynucleotide strands twisted into a spiral

3) has a nucleotide containing uracil

4) has a nucleotide containing thymine

5) preserves hereditary information

6) transfers information about the structure of the protein from the nucleus to the ribosome

13 . How is an mRNA molecule different from DNA?

1) transfers hereditary information from the nucleus to the ribosome

2) nucleotides include residues of nitrogenous bases, carbohydrates and phosphoric acid

3) consists of one polynucleotide strand

4) consists of two polynucleotide strands interconnected

5) it contains the carbohydrate ribose and the nitrogenous base uracil

6) it contains the carbohydrate deoxyribose and the nitrogenous base thymine

14. All but two of the following features are functions of lipids. Identify two characteristics that “drop out” from the general list and write down the numbers under which they are indicated in the table.

1) storing

2) hormonal

3) enzymatic

4) carrier of hereditary information

5) energy

15. All of the signs below, except two, can be used to describe the significance of proteins in the human and animal body. Identify two characteristics that “drop out” from the general list, and write down the numbers under which they are indicated in your answer.

1) serve as the main building material

2) are broken down in the intestines to glycerol and fatty acids

3) are formed from amino acids

4) in the liver they are converted into glycogen

5) as enzymes they accelerate chemical reactions

16 .All of the features listed below, except two, can be used to describe a DNA molecule. Identify two characteristics that “drop out” from the general list and write down the numbers under which they are indicated in the table.

1) consists of two polynucleotide chains twisted into a spiral

2) transfers information to the site of protein synthesis

3) in combination with proteins, builds the body of the ribosome

4) capable of self-doubling

5) in combination with proteins forms chromosomes

17 . All but two of the features listed below can be used to describe the insulin molecule. Identify two characteristics that “drop out” from the general list and write down the numbers under which they are indicated in the table

1) consists of amino acids

2) adrenal hormone

3) a catalyst for many chemical reactions

4) pancreatic hormone

5) a substance of protein nature

18 All but two of the following characteristics can be used to describe egg white albumin. Identify two characteristics that “drop out” from the general list and write down the numbers under which they are indicated in the table.

1) consists of amino acids

2) digestive enzyme

3) denatures reversibly when boiling eggs

4) monomers are connected by peptide bonds

5) the molecule forms primary, secondary and tertiary structures

19 All but two of the characteristics listed below can be used to describe a starch molecule. Identify two characteristics that “drop out” from the general list and write down the numbers under which they are indicated in the table.

1) consists of one chain

2) dissolves well in water

3) in combination with proteins forms a cell wall

4) undergoes hydrolysis

5) is a reserve substance in muscle cells

20. Select cell organelles containing hereditary information.

1) core

2) lysosomes

3) Golgi apparatus

4) ribosomes

5) mitochondria

6) chloroplasts

21Task 4 Select structures that are characteristic only of a plant cell.

1) mitochondria

2) chloroplasts

3) cell wall

4) ribosomes

5) vacuoles with cell sap

6) Golgi apparatus

22 Viruses, unlike bacteria,

1) have a cell wall

2) adapt to the environment

3) consist only of nucleic acid and protein

4) reproduce vegetatively

5) do not have their own metabolism

23. Similar structure of plant and animal cells - proof

1) their relationship

2) the common origin of organisms of all kingdoms

3) the origin of plants from animals

4) complications of organisms in the process of evolution

5) unity of the organic world

6) diversity of organisms

24 What functions does the Golgi complex perform?

1) synthesizes organic substances from inorganic ones

2) breaks down biopolymers into monomers

3) accumulates proteins, lipids, carbohydrates synthesized in the cell

4) ensures packaging and removal of substances from the cell

5) oxidizes organic substances to inorganic ones

6) participates in the formation of lysosomes

25 Autotrophs include

1) spore plants

2) molds

3) unicellular algae

4) chemotrophic bacteria

5) viruses

6) most protozoa

26 Which of the following organelles are membranous?

1) lysosomes

2) centrioles

3) ribosomes

4) microtubules

5) vacuoles

6) leucoplasts

27 Select the provisions of the synthetic theory of evolution.

1) Species actually exist in nature and are formed over a long period of time.

2) Mutations and combinations of genes serve as material for evolution.

3) The driving forces of evolution are the mutation process, population waves, and combinative variability.

4) In nature, there are various types of struggle for existence between organisms.

5) Natural selection is the guiding factor of evolution.

6) Natural selection preserves some individuals and destroys others.

28 What substances make up the cell membrane?

1) lipids

2) chlorophyll

3) RNA

4) carbohydrates

5) proteins

6) DNA

29. In which of the listed cell organelles do matrix synthesis reactions occur?

1) centrioles

2) lysosomes

3) Golgi apparatus

4) ribosomes

5) mitochondria

6) chloroplasts

30. Eukaryotes include

1) ordinary amoeba

2) yeast

4) Vibrio cholerae

5) E. coli

6) human immunodeficiency virus

31. Prokaryotic cells are different from eukaryotic cells

1) the presence of a nucleoid in the cytoplasm

2) the presence of ribosomes in the cytoplasm

3) ATP synthesis in mitochondria

4) the presence of the endoplasmic reticulum

5) absence of a morphologically distinct nucleus

6) the presence of invaginations of the plasma membrane, performing the function of membrane organelles

32.What are the features of the structure and functions of mitochondria

1) the inner membrane forms grana

2) are part of the core

3) synthesize their own proteins

4) participate in the oxidation of organic substances to And

5) provide glucose synthesis

6) are the site of ATP synthesis

33. Which of the following functions does the plasma membrane of a cell perform? Write down the numbers in ascending order as your answer.

1) participates in lipid synthesis

2) carries out active transport of substances

3) participates in the process of phagocytosis

4) participates in the process of pinocytosis

5) is the site of synthesis of membrane proteins

6) coordinates the process of cell division

34. What are the features of the structure and functions of ribosomes? Write down the numbers in ascending order as your answer.

1) have one membrane

2) consist of DNA molecules

3) break down organic substances

4) consist of large and small particles

5) participate in the process of protein biosynthesis

6) consist of RNA and protein

35. Which of the following organelles are membrane-bound? Write down the numbers in ascending order as your answer.

1) lysosomes

2) centrioles

3) ribosomes

4) vacuoles

5) leucoplasts

6) microtubules

36.All of the following features, except two, can be used to describe the functions of the cytoplasm. Identify two characteristics that “drop out” from the general list, and write down the numbers under which they are indicated in your answer.

1) the internal environment in which the organelles are located

2) glucose synthesis

3) relationships between metabolic processes

4) oxidation of organic substances to inorganic ones

5) communication between cell organelles

37.All of the following features, except two, can be used to characterize the general properties of mitochondria and chloroplasts. Identify two characteristics that “drop out” from the general list and write down the numbers under which they are indicated in the table.

1) form lysosomes

2) are double membrane

3) are semi-autonomous organelles

4) participate in ATP synthesis

5) form a spindle

38All of the characteristics listed below, except two, can be used to describe the cell organelle shown in the figure. Identify two characteristics that “drop out” from the general list, and write down the numbers under which they are indicated in the table.

1) found in plant and animal cells

2) characteristic of prokaryotic cells

3) participates in the formation of lysosomes

4) forms secretory vesicles

5) double-membrane organelle

39All of the characteristics listed below, except two, can be used to describe the cell organelle shown in the figure. Identify two characteristics that “drop out” from the general list and write down the numbers under which they are indicated in the table.

1) single-membrane organelle

2) consists of cristae and chromatin

3) contains circular DNA

4) synthesizes its own protein

5) capable of division

40. All of the characteristics listed below, except two, can be used to describe the cell organelle shown in the figure. Identify two characteristics that “drop out” from the general list, and write down the numbers under which they are indicated in the table.

1) single-membrane organelle

2) contains fragments of ribosomes

3) the shell is riddled with pores

4) contains DNA molecules

5) contains mitochondria

41 All of the characteristics listed below, except two, can be used to describe the cell shown in the figure. Identify two characteristics that “drop out” from the general list; Write down the numbers under which they are indicated in the table.

1) there is a cell membrane

2) the cell wall consists of chitin

3) the hereditary apparatus is contained in a ring chromosome

4) storage substance - glycogen

5) the cell is capable of photosynthesis

42All of the characteristics listed below, except two, can be used to describe the cell shown in the figure. Identify two characteristics that “drop out” from the general list; write down the numbers under which they are indicated in the table

1) there is a cell membrane

2) there is a Golgi apparatus

3) there are several linear chromosomes

4) there are ribosomes

5) there is a cell wall

Chemical composition of the cell

All living things are characterized by a selective attitude towards the environment. Of the 110 elements of D.I. Mendeleev’s periodic table, more than half are included in the composition of organisms. However, there are only about 20 elements necessary for life, without which living things cannot do.

All these elements are part of inanimate nature and the earth's crust, as well as living organisms, but their percentage distribution in living and nonliving bodies is different.

Elemental composition of living matter

Molecular biology, which develops in close contact with biochemistry, is involved in the accumulation of knowledge about biomolecules. Biochemistry studies life at the level of molecules and elements.

Macronutrients(Greek macros- large and lat. elemėntum- original substance) - chemical elements that are the main components of all living organisms. These include oxygen, hydrogen, carbon, nitrogen, iron, phosphorus, potassium, calcium, sulfur, magnesium, sodium and chlorine. These elements are also universal components of organic compounds. Their concentration reaches a total of 98 - 99%.

All macroelements are divided into 2 groups.

The role of macroelements of groups I and II

Content of bioelements in the cell

Microelements(Greek mikros- small and lat. elemėntum- original substance) - chemical elements contained in organisms in low concentrations (usually thousandths of a percent or less), but extremely necessary for normal life. These are aluminum, copper, manganese, zinc, molybdenum, cobalt, nickel, iodine, selenium, bromine, fluorine, boron and some others.

Microelements are part of a variety of biologically active compounds: enzymes (for example, Zn, Cu, Mn, Mo; in total about 200 metalloenzymes are known), vitamins (Co - in vitamin B 12), hormones (I - in thyroxine, Zn and Co - into insulin ) , respiratory pigments (Cu - to hemocyanin). Microelements affect growth, reproduction, hematopoiesis, etc.

The role of microelements in the body

Cobalt is part of vitamin B 12 and takes part in the synthesis hemoglobin , its deficiency leads to anemia.

1 - cobalt in nature; 2 - structural formula of vitamin B 12; 3 - red blood cells of a healthy person and red blood cells of an anemic person

Molybdenum As part of enzymes, it participates in nitrogen fixation in bacteria and ensures the functioning of the stomatal apparatus in plants.

1 - molybdenite (mineral containing molybdenum); 2 - nitrogen-fixing bacteria; 3 - stomatal apparatus

Copper is a component of an enzyme involved in the synthesis melanin(skin pigment), affects the growth and reproduction of plants, and the processes of hematopoiesis in animal organisms.

1 - copper; 2 - melanin particles in skin cells; 3 - plant growth and development

Iodine in all vertebrates it is part of the thyroid hormone - thyroxine .

1 - iodine; 2 - appearance of the thyroid gland; 3 - thyroid cells that synthesize thyroxine

Bor affects the growth processes of plants; its deficiency leads to the death of apical buds, flowers and ovaries.

1 - boron in nature; 2 - spatial structure of boron; 3 - apical bud

Zinc is part of the pancreatic hormone - insulin, and also affects the growth of animals and plants.

1 - spatial structure of insulin; 2 - pancreas; 3 - growth and development of animals

Microelements enter the organisms of plants and microorganisms from soil and water; into the organisms of animals and humans - with food, in natural waters and with air.

TEST

The chemical composition of living organisms can be expressed in two forms - atomic and molecular.

Atomic (elemental) composition characterizes the ratio of atoms of elements included in living organisms.
Molecular (material) composition reflects the ratio of molecules of substances.

Elemental composition

Based on their relative content, the elements that make up living organisms are divided into three groups.

Groups of elements according to their content in living organisms

Macroelements make up the bulk of the percentage composition of living organisms.

Content of some chemical elements in natural objects

Chemical elements that are part of living organisms and at the same time perform biological functions are called biogenic. Even those of them that are contained in cells in negligible quantities cannot be replaced by anything and are absolutely necessary for life. These are mainly macro- and microelements. The physiological role of most microelements has not been revealed.

The role of nutrients in living organisms

Molecular composition

Chemical elements are part of cells in the form of ions and molecules of inorganic and organic substances. The most important inorganic substances in the cell are water and mineral salts, the most important organic substances are carbohydrates, lipids, proteins and nucleic acids.

Chemical content in the cell

Inorganic substances

Water

Water- the predominant substance of all living organisms. It has unique properties due to its structural features: water molecules have the shape of a dipole and hydrogen bonds are formed between them. The average water content in the cells of most living organisms is about 70%. Water in the cell is present in two forms: free(95% of all cell water) and related(4–5% protein bound). The functions of water are presented in the table.

Functions of water

Mineral salts

Mineral salts in an aqueous solution, cells dissociate into cations and anions.
The most important cations are K +, Ca 2+, Mg 2+, Na +, NH 4+,
The most important anions are Cl -, SO 4 2-, HPO 4 2-, H 2 PO 4 -, HCO 3 -, NO 3 -.
It is not only the concentration that is important, but also the ratio of individual ions in the cell.
The functions of minerals are presented in the table.

Functions of minerals

In addition, hydrochloric acid is part of the gastric juice of animals and humans, accelerating the process of digesting food proteins. Residues of sulfuric acid help remove foreign substances from the body. Sodium and potassium salts of nitrous and phosphoric acids, calcium salt of sulfuric acid serve as important components of mineral nutrition of plants; they are added to the soil as fertilizers.

Organic matter

Polymer- a multi-link chain in which the link is some relatively simple substance - a monomer. There are polymers linear and branched, homopolymers(all monomers are the same - glucose residues in starch) and heteropolymers(different monomers - amino acid residues in proteins), regular(a group of monomers in a polymer repeats periodically) and irregular(there is no visible repeatability of monomer units in the molecules).
Biological polymers- These are polymers that are part of the cells of living organisms and their metabolic products. Biopolymers are proteins, nucleic acids, and polysaccharides. The properties of biopolymers depend on the number, composition and order of arrangement of their constituent monomers. Changing the composition and sequence of monomers in the polymer structure leads to a significant number of variants of biological macromolecules.

Carbohydrates

Carbohydrates- organic compounds consisting of one or many molecules of simple sugars. The carbohydrate content in animal cells is 1–5%, and in some plant cells it reaches 70%.
There are three groups of carbohydrates: monosaccharides, oligosaccharides(consist of 2–10 molecules of simple sugars), polysaccharides(consist of more than 10 sugar molecules). By combining with lipids and proteins, carbohydrates form glycolipids and glycoproteins.

Characteristics of carbohydrates

The functions of carbohydrates are presented in the table.

Functions of carbohydrates

Lipids

Lipids- fats and fat-like organic compounds, practically insoluble in water. Their content in different cells varies greatly from 2–3 (in plant seed cells) to 50–90% (in animal adipose tissue). Chemically, lipids are usually esters of fatty acids and a number of alcohols

They are divided into several classes. Most common in wildlife neutral fats, waxes, phospholipids, steroids. Most lipids contain fatty acids, the molecules of which contain a hydrophobic long-chain hydrocarbon “tail” and a hydrophilic carboxyl group.
Fats- esters of the trihydric alcohol glycerol and three molecules of fatty acids. Wax are esters of polyhydric alcohols and fatty acids. Phospholipids have a phosphoric acid residue in the molecule instead of a fatty acid residue. Steroids do not contain fatty acids and have a special structure. Also characteristic of living organisms lipoproteins- compounds of lipids with proteins without the formation of covalent bonds and glycolipids- lipids that, in addition to a fatty acid residue, contain one or more sugar molecules.
The functions of lipids are presented in the table.

Functions of lipids

Squirrels

Proteins are the largest and most diverse class of organic compounds in the cell. Squirrels are biological heteropolymers whose monomers are amino acids.

By chemical composition amino acids- these are compounds containing one carboxyl group (-COOH) and one amine group (-NH 2), connected to one carbon atom to which a side chain is attached - some radical R. It is the radical that gives the amino acid its unique properties.
Only 20 amino acids are involved in the formation of proteins. They're called fundamental, or main: alanine, methionine, valine, proline, leucine, isoleucine, tryptophan, phenylalanine, asparagine, glutamine, serine, glycine, tyrosine, threonine, cysteine, arginine, histidine, lysine, aspartic and glutamic acids. Some of the amino acids are not synthesized in animals and humans and must be obtained from plant foods. They are called essential: arginine, valine, histidine, isoleucine, leucine, lysine, methionine, threonine, tryptophan, phenylalanine.
Amino acids joining each other covalently peptide bonds, form peptides of varying lengths
A peptide (amide) bond is a covalent bond formed by the carboxyl group of one amino acid and the amine group of another.
Proteins are high molecular weight polypeptides containing from one hundred to several thousand amino acids.
There are 4 levels of protein organization:

Levels of protein organization

The configuration of a protein depends on the sequence of amino acids, but it can also be influenced by the specific conditions in which the protein is located.
The loss of a protein molecule's structural organization is called denaturation.

Denaturation may be reversible And irreversible. With reversible denaturation, the quaternary, tertiary and secondary structures are destroyed, but due to the preservation of the primary structure, when normal conditions return, it is possible renaturation protein - restoration of normal (native) conformation. With irreversible denaturation, the primary structure of the protein is destroyed. Denaturation can be caused by high temperature (above 45 °C), dehydration, ionizing radiation and other factors. Changes in the conformation (spatial structure) of a protein molecule underlie a number of protein functions (signaling, antigenic properties, etc.).
Based on their chemical composition, simple and complex proteins are distinguished. Simple proteins consist only of amino acids (fibrillar proteins, antibodies - immunoglobulins). Complex proteins contain a protein part and a non-protein part - prosthetic groups. Distinguish lipoproteins(contain lipids) glycoproteins(carbohydrates), phosphoproteins(one or more phosphate groups), metalloproteins(various metals), nucleoproteins(nucleic acids). Prosthetic groups usually play an important role in a protein performing its biological function.
The functions of proteins are presented in the table.

Functions of proteins

Enzymes. Enzyme proteins catalyze chemical reactions in the body. These reactions, due to energetic reasons, either do not occur in the body at all, or proceed too slowly.
The enzymatic reaction can be expressed by the general equation:
E+S → → E+P,
where the substrate (S) reacts reversibly with the enzyme (E) to form an enzyme-substrate complex (ES), which then decomposes to form the reaction product (P). The enzyme is not part of the final reaction products.
The enzyme molecule contains active center, consisting of two sections - sorption(responsible for binding the enzyme to the substrate molecule) and catalytic(responsible for the course of catalysis itself). During the reaction, the enzyme binds the substrate, sequentially changes its configuration, forming a series of intermediate molecules that ultimately produce reaction products.
The difference between enzymes and inorganic catalysts:
1. One enzyme catalyzes only one type of reaction.
2. Enzyme activity is limited to a fairly narrow temperature range (usually 35–45 o C).
3. Enzymes are active at certain pH values ​​(most in a slightly alkaline environment).

Nucleic acids

Mononucleotides. A mononucleotide consists of one nitrogenous base - purine(adenine - A, guanine - G) or pyrimidine(cytosine - C, thymine - T, uracil - U), pentose sugars (ribose or deoxyribose) and 1-3 phosphoric acid residues.
Depending on the number of phosphate groups, mono-, di- and triphosphates of nucleotides are distinguished, for example, adenosine monophosphate - AMP, guanosine diphosphate - HDP, uridine triphosphate - UTP, thymidine triphosphate - TTP, etc.
The functions of mononucleotides are presented in the table.

Functions of mononucleotides

Polynucleotides. Nucleic acids (polynucleotides)- polymers whose monomers are nucleotides. There are two types of nucleic acids: DNA (deoxyribonucleic acid) and RNA (ribonucleic acid).
DNA and RNA nucleotides consist of the following components:

1. Nitrogen base(in DNA: adenine, guanine, cytosine and thymine; in RNA: adenine, guanine, cytosine and uracil).
2. Pentose sugar(in DNA - deoxyribose, in RNA - ribose).
3. Phosphoric acid residue.

​DNA (deoxyribonucleic acid)- a linear polymer consisting of four types of monomers: nucleotides A, T, G and C, linked to each other by a covalent bond through phosphoric acid residues.

The DNA molecule consists of two spirally twisted chains (double helix). In this case, two hydrogen bonds are formed between adenine and thymine, and three between guanine and cytosine. These pairs of nitrogenous bases are called complementary. In a DNA molecule they are always located opposite each other. The chains in a DNA molecule are in opposite directions. The spatial structure of the DNA molecule was established in 1953 by D. Watson and F. Crick.

By binding to proteins, the DNA molecule forms a chromosome. Chromosome- a complex of one DNA molecule with proteins. DNA molecules of eukaryotic organisms (fungi, plants and animals) are linear, open-ended, linked to proteins, forming chromosomes. In prokaryotes (bacteria), DNA is closed in a ring, not associated with proteins, and does not form a linear chromosome.

DNA Function: storage, transmission and reproduction of genetic information over generations. DNA determines which proteins need to be synthesized and in what quantities.
RNA (ribonucleic acids) Unlike DNA, they contain ribose instead of deoxyribose, and uracil instead of thymine. RNA typically has only one strand, which is shorter than DNA strands. Double-stranded RNA is found in some viruses.
There are 3 types of RNA.

Types of RNA

Functions of RNA: participation in protein biosynthesis.
Self duplication of DNA. DNA molecules have an ability that is not inherent in any other molecule - the ability to duplicate. The process of doubling DNA molecules is called replication.

Replication is based on the principle of complementarity - the formation of hydrogen bonds between nucleotides A and T, G and C.
Replication is carried out by DNA polymerase enzymes. Under their influence, the chains of DNA molecules are separated into a small segment of the molecule. On the chain of the mother molecule, daughter chains are completed. Then a new segment is unraveled, and the replication cycle repeats.
As a result, daughter DNA molecules are formed that are no different from each other or from the parent molecule. During cell division, daughter DNA molecules are distributed among the resulting cells. This is how information is passed on from generation to generation.
Under the influence of various environmental factors (ultraviolet radiation, various chemicals), the DNA molecule can be damaged. Chain breaks, erroneous substitutions of nitrogenous bases of nucleotides, etc. occur. In addition, changes in DNA can occur spontaneously, for example, as a result recombination- exchange of DNA fragments. The changes that occur in hereditary information are also transmitted to the offspring.
In some cases, DNA molecules are able to “correct” changes that occur in its chains. This ability is called reparation. The restoration of the original DNA structure involves proteins that recognize altered sections of DNA and remove them from the chain, thereby restoring the correct nucleotide sequence by stitching the restored fragment with the rest of the DNA molecule.
Comparative characteristics of DNA and RNA are presented in the table.

Comparative characteristics of DNA and RNA

Cell structure Cell theory

The formation of cell theory:

• Robert Hooke discovered cells in a section of cork in 1665 and first used the term cell.
• Anthony van Leeuwenhoek discovered single-celled organisms.
• Matthias Schleiden in 1838 and Thomas Schwann in 1839 formulated the basic principles of cell theory. However, they mistakenly believed that cells arise from a primary noncellular substance.
• Rudolf Virchow proved in 1858 that all cells are formed from other cells through cell division.

Basic principles of cell theory:

1. The cell is structural unit all living things. All living organisms are made up of cells (with the exception of viruses).
2. The cell is functional unit all living things. The cell exhibits the entire complex of vital functions.
3. The cell is development unit all living things. New cells are formed only as a result of division of the original (mother) cell.
4. The cell is genetic unit all living things. The chromosomes of a cell contain information about the development of the entire organism.
5. The cells of all organisms are similar in chemical composition, structure and functions.

Types of Cellular Organization

Among living organisms, only viruses do not have a cellular structure. All other organisms are represented by cellular life forms. There are two types of cellular organization: prokaryotic and eukaryotic. Prokaryotes include bacteria and cyanobacteria (blue-green), while eukaryotes include plants, fungi and animals.

Prokaryotic cells are arranged relatively simply. They do not have a nucleus, the area where DNA is located in the cytoplasm is called a nucleoid, the only DNA molecule is circular and not associated with proteins, the cells are smaller than eukaryotic ones, the cell wall includes a glycopeptide - murein, there are no membrane organelles, their functions are performed by invaginations of the plasma membrane (mesosomes), ribosomes are small, microtubules are absent, so the cytoplasm is motionless, and cilia and flagella have a special structure.

Eukaryotic cells have a nucleus in which chromosomes are located - linear DNA molecules associated with proteins; various membrane organelles are located in the cytoplasm.
Plant cells They are distinguished by the presence of a thick cellulose cell wall, plastids, and a large central vacuole that displaces the nucleus to the periphery. The cell center of higher plants does not contain centrioles. The storage carbohydrate is starch.
Fungal cells have a cell wall containing chitin, a central vacuole in the cytoplasm, and no plastids. Only some fungi have a centriole in the cell center. The main reserve carbohydrate is glycogen.
Animal cells do not have a cell wall, do not contain plastids and a central vacuole, the cell center is characterized by a centriole. The storage carbohydrate is glycogen.
Depending on the number of cells that make up organisms, they are divided into unicellular and multicellular. Unicellular organisms consist of a single cell that performs the functions of an entire organism. All prokaryotes are unicellular, as well as protozoa, some green algae and fungi. Body multicellular organisms consists of many cells united into tissues, organs and organ systems. The cells of a multicellular organism are specialized to perform a specific function and can exist outside the body only in a microenvironment close to the physiological one (for example, in tissue culture conditions). Cells within a multicellular organism vary in size, shape, structure, and functions. Despite their individual characteristics, all cells are built according to a single plan and have many common features.

Characteristics of eukaryotic cell structures

Main differences between prokaryotic and eukaryotic cells