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The chemical organization of the cell. inorganic substances. organic matter. Organic and inorganic substances of the cell

All organisms on our planet are made up of cells that are similar in chemical composition. In this article, we will briefly talk about the chemical composition of the cell, its role in the life of the whole organism, and find out what science studies this issue.

Groups of elements of the chemical composition of the cell

The science that studies the constituent parts and structure of a living cell is called cytology.

All elements included in the chemical structure of the body can be divided into three groups:

• macronutrients;
• trace elements;
• ultramicroelements.

Macronutrients include hydrogen, carbon, oxygen and nitrogen. Almost 98% of all constituent elements fall on their share.

Trace elements are available in tenths and hundredths of a percent. And a very small content of ultramicroelements - hundredths and thousandths of a percent.

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Translated from Greek, “macro” means large, and “micro” means small.

Scientists have found that there are no special elements that are inherent only in living organisms. Therefore, that living, that inanimate nature consists of the same elements. This proves their relationship.

Despite the quantitative content of a chemical element, the absence or reduction of at least one of them leads to the death of the whole organism. After all, each of them has its own meaning.

The role of the chemical composition of the cell

Macronutrients are the basis of biopolymers, namely proteins, carbohydrates, nucleic acids and lipids.

Trace elements are part of the vital organic substances involved in metabolic processes. They are the constituent components of mineral salts, which are in the form of cations and anions, their ratio determines the alkaline environment. Most often, it is slightly alkaline, because the ratio of mineral salts does not change.

Hemoglobin contains iron, chlorophyll - magnesium, proteins - sulfur, nucleic acids - phosphorus, metabolism occurs with a sufficient amount of calcium.

Rice. 2. Composition of the cell

Some chemical elements are components of inorganic substances, such as water. She plays big role in the life of both plant and animal cells. Water is a good solvent, because of this, all substances inside the body are divided into:

• hydrophilic - dissolve in water;
• Hydrophobic - do not dissolve in water.

Due to the presence of water, the cell becomes elastic, it contributes to the movement of organic substances in the cytoplasm.

Rice. 3. Substances of the cell.

Table “Properties of the chemical composition of the cell”

To clearly understand what chemical elements are part of the cell, we have included them in the following table:

Elements		Meaning
Macronutrients
Oxygen, carbon, hydrogen, nitrogen
		An integral component of the shell in plants, in the animal body is in the composition of bones and teeth, takes an active part in blood clotting.
		Contained in nucleic acids, enzymes, bone tissue and tooth enamel.
trace elements
		It is the basis of proteins, enzymes and vitamins.
		Provides transmission of nerve impulses, activates protein synthesis, photosynthesis and growth processes.
		One of the components of gastric juice, an enzyme provocateur.
		Takes an active part in metabolic processes, a component of the thyroid hormone.
		Provides impulse transmission nervous system, maintains constant pressure inside the cell, provokes the synthesis of hormones.
		A component of chlorophyll, bone tissue and teeth, provokes DNA synthesis and heat transfer processes.
		An integral part of hemoglobin, lens, cornea, synthesizes chlorophyll. Transports oxygen throughout the body.
Ultramicroelements
		An integral part of the processes of blood formation, photosynthesis, accelerates intracellular oxidation processes.
Manganese		It activates photosynthesis, participates in blood formation, provides high yield.
		Component of tooth enamel.
		Regulates plant growth.

What have we learned?

Each living cell has its own set chemical elements. According to their composition, objects of animate and inanimate nature have similarities, this proves their close relationship. Each cell consists of macronutrients, micronutrients and ultramicronutrients, each of which has its own role. The absence of at least one of them leads to disease and even death of the whole organism.

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Plant and animal cells contain inorganic and organic substances. Inorganic materials include water and minerals. Organic substances include proteins, fats, carbohydrates, nucleic acids.

inorganic substances

Wateris the compound that a living cell contains in the largest amount. Water makes up about 70% of the mass of the cell. Most intracellular reactions take place in aquatic environment. Water in the cell is in a free and bound state.

The importance of water for the life of a cell is determined by its structure and properties. The water content in cells can be different. 95% of the water is in the cell in a free state. It is necessary as a solvent for organic and inorganic substances. All biochemical reactions in the cell take place with the participation of water. Water is used to remove various substances from the cell. Water has a high thermal conductivity and prevents sudden temperature fluctuations. 5% of water is in a bound state, forming fragile compounds with proteins.

Minerals in a cell can be in a dissociated state or in combination with organic substances.

Chemical elements, which participate in metabolic processes and have biological activity are called biogenic.

Cytoplasmcontains about 70% oxygen, 18% carbon, 10% hydrogen, calcium, nitrogen, potassium, phosphorus, magnesium, sulfur, chlorine, sodium, aluminum, iron. These elements make up 99.99% of the composition of the cell and are called macronutrients. For example, calcium and phosphorus are found in bones. Iron - component hemoglobin.

Manganese, boron, copper, zinc, iodine, cobalt - trace elements. They make up thousandths of a percent of the mass of the cell. Trace elements are needed for the formation of hormones, enzymes, vitamins. They affect the metabolic processes in the body. For example, iodine is part of the thyroid hormone, cobalt is part of vitamin B12.

Gold, mercury, radium, etc. - ultramicroelements- make up millionths of a percent of the composition of the cell.

The lack or excess of mineral salts disrupts the vital activity of the body.

organic matter

Oxygen, hydrogen, carbon, nitrogen are part of organic substances. Organic compounds are large molecules called polymers. Polymers are made up of many repeating units (monomers). Organic polymeric compounds include carbohydrates, fats, proteins, nucleic acids, ATP.

Carbohydrates

Carbohydratesare made up of carbon, hydrogen and oxygen.

Monomerscarbohydrates are monosaccharides. Carbohydrates are divided into monosaccharides, disaccharides and polysaccharides.

Monosaccharides- simple sugars with the formula (CH 2 O) n, where n is any integer from three to seven. Depending on the number of carbon atoms in a molecule, trioses (3C), tetroses (4C), pentoses (5C), hexoses (6C), and heptoses (7C) are distinguished.

TriosesC 3 H 6 O 3 - for example, glyceraldehyde and dihydroxyacetone - play the role of intermediate products in the process of respiration, participate in photosynthesis. Tetroses C 4 H 8 O 4 are found in bacteria. Pentoses C 5 H 10 O 5 - for example, ribose - is part of RNA, deoxyribose is part of DNA. Hexoses - C 6 H 12 O 6 - for example glucose, fructose, galactose. Glucose is a source of energy for the cell. Together with fructose and galactose, glucose can participate in the formation of disaccharides.

disaccharidesare formed as a result of a condensation reaction between two monosaccharides (hexoses) with the loss of a water molecule.

The formula of disaccharides C 12 H 22 O 11 Among the disaccharides, maltose, lactose and sucrose are the most widespread.

Sucrose, or cane sugar, is synthesized in plants. Maltose is formed from starch during its digestion in the body of animals. Lactose, or milk sugar, is found only in milk.

Polysaccharides (simple) formed as a result of the condensation reaction a large number monosaccharides. Simple polysaccharides include starch (synthesized in plants), glycogen (found in liver cells and muscles of animals and humans), cellulose (forms a cell wall in plants).

Complex polysaccharides formed as a result of the interaction of carbohydrates with lipids. For example, glycolipids are part of membranes. Complex polysaccharides also include compounds of carbohydrates with proteins (glycoproteins). For example, glycoproteins are part of the mucus secreted by the glands of the gastrointestinal tract.

Functions of carbohydrates:

1. Energy: 60% of the body's energy comes from the breakdown of carbohydrates. When splitting 1 g of carbohydrates, 17.6 kJ of energy is released.

2. Structural and supporting: carbohydrates are part of the plasma membrane, the shell of plant and bacterial cells.

3. Reserve: nutrients (glycogen, starch) are stored in the cells.

4. Protective: secrets (mucus) secreted by various glands protect the walls of hollow organs, bronchi, stomach, intestines from mechanical damage, harmful bacteria and viruses.

5. Participate in photosynthesis.

Fats and fat-like substances

Fatsare made up of carbon, hydrogen and oxygen. Monomers fats are fatty acid And glycerol. The properties of fats are determined qualitative composition fatty acids and their proportions. Vegetable fats are liquid (oils), animals are solid (for example, lard). Fats are insoluble in water - they are hydrophobic compounds. Fats combine with proteins to form lipoproteins, and combine with carbohydrates to form glycolipids. Glycolipids and lipoproteins are fat-like substances.

Fat-like substances are part of cell membranes, membrane organelles, and nervous tissue. Fats can combine with glucose and form glycosides. For example, digitoxin glycoside is a substance used in the treatment of heart disease.

Functions of fats:

1. Energy: with the complete breakdown of 1 g of fat to carbon dioxide and water, 38.9 kJ of energy is released.

2. Structural: are part of the cell membrane.

3. Protective: a layer of fat protects the body from hypothermia, mechanical shocks and concussions.

4. Regulatory: steroid hormones regulate metabolic processes and reproduction.

5. Fat- source endogenous water. When 100 g of fat is oxidized, 107 ml of water is released.

Squirrels

Proteins are made up of carbon, oxygen, hydrogen, and nitrogen. Monomers protein are amino acids. Proteins are built from twenty different amino acids. Amino acid formula:

The composition of amino acids includes: NH 2 - an amino group with basic properties; COOH - carboxyl group, has acidic properties. Amino acids differ from each other by their radicals - R. Amino acids are amphoteric compounds. They are connected to each other in a protein molecule using peptide bonds.

Amino acid condensation scheme (peptide bond formation)

There are primary, secondary, tertiary and quaternary protein structures. The order, quantity and quality of amino acids that make up a protein molecule determine its primary structure. Proteins of the primary structure can be connected into a spiral with the help of hydrogen bonds and form a secondary structure. Polypeptide chains twist in a certain way into a compact structure, forming a globule (ball) - this is the tertiary structure of the protein. Most proteins have a tertiary structure. Amino acids are active only on the surface of the globule. Proteins that have a globular structure come together to form a quaternary structure. The replacement of one amino acid leads to a change in the properties of the protein (Fig. 30).

Under the influence of high temperature, acids and other factors, the destruction of the protein molecule can occur. This phenomenon is called denaturation (Fig. 31). Sometimes denatured

Rice. thirty.Various structures of protein molecules.

1 - primary; 2 - secondary; 3 - tertiary; 4 - Quaternary (on the example of blood hemoglobin).

Rice. 31.protein denaturation.

1 - protein molecule before denaturation;

2 - denatured protein;

3 - restoration of the original protein molecule.

The bathed protein, when conditions change, can again restore its structure. This process is called renaturation and is possible only when the primary structure of the protein is not destroyed.

Proteins are simple and complex. Simple proteins consist only of amino acids: for example, albumins, globulins, fibrinogen, myosin.

Complex proteins are composed of amino acids and other organic compounds: eg lipoproteins, glycoproteins, nucleoproteins.

Protein Functions:

1. Energy. The breakdown of 1 g of protein releases 17.6 kJ of energy.

2. catalytic. They serve as catalysts for biochemical reactions. Catalysts are enzymes. Enzymes speed up biochemical reactions, but are not part of the final products. Enzymes are strictly specific. Each substrate has its own enzyme. The name of the enzyme includes the name of the substrate and the ending "ase": maltase, ribonuclease. Enzymes are active at a certain temperature (35 - 45 ° C).

3. Structural. Proteins are part of the membranes.

4. Transport. For example, hemoglobin carries oxygen and CO 2 in the blood of vertebrates.

5. Protective. Protecting the body from harmful influences: the production of antibodies.

6. Contractile. Due to the presence of actin and myosin proteins in muscle fibers muscle contraction occurs.

Nucleic acids

There are two types of nucleic acids: DNA(deoxyribonucleic acid) and RNA(ribonucleic acid). Monomers nucleic acids are nucleotides.

DNA (deoxyribonucleic acid). The composition of the DNA nucleotide includes one of the nitrogenous bases: adenine (A), guanine (G), thymine (T) or cytosine (C) (Fig. 32), a deoxyribose carbohydrate and a phosphoric acid residue. The DNA molecule is a double helix built on the principle of complementarity. The following nitrogenous bases are complementary in the DNA molecule: A = T; G \u003d C. Two helixes of DNA are connected by hydrogen bonds (Fig. 33).

Rice. 32.The structure of a nucleotide.

Rice. 33.Section of a DNA molecule. Complementary connection of nucleotides of different chains.

DNA is capable of self-duplication (replication) (Fig. 34). Replication begins with the separation of two complementary strands. Each strand is used as a template for the formation of a new DNA molecule. Enzymes are involved in the process of DNA synthesis. Each of the two daughter molecules necessarily includes one old helix and one new one. The new DNA molecule is absolutely identical to the old one in terms of nucleotide sequence. This method of replication ensures the exact reproduction in the daughter molecules of the information that was recorded in the parent DNA molecule.

Rice. 34.Doubling of the DNA molecule.

1 - matrix DNA;

2 - the formation of two new chains based on the matrix;

3 - daughter DNA molecules.

DNA functions:

1. Storage of hereditary information.

2. Ensuring the transfer of genetic information.

3. Presence in the chromosome as a structural component.

DNA is found in the nucleus of the cell, as well as in such cell organelles as mitochondria, chloroplasts.

RNA (ribonucleic acid). Ribonucleic acids are of 3 types: ribosomal, transport And informational RNA. An RNA nucleotide consists of one of the nitrogenous bases: adenine (A), guanine (G), cytosine (C), uracil (U), carbohydrate - ribose and a phosphoric acid residue.

Ribosomal RNA (rRNA) in combination with the protein is part of the ribosomes. rRNA makes up 80% of all RNA in a cell. Protein synthesis takes place on ribosomes.

Messenger RNA (mRNA) makes up from 1 to 10% of all RNA in the cell. The structure of mRNA is complementary to that part of the DNA molecule. carrying information about the synthesis of a particular protein. The length of the mRNA depends on the length of the DNA segment from which the information was read. mRNA transfers information about protein synthesis from the nucleus to the cytoplasm to the ribosome.

Transfer RNA (tRNA) makes up about 10% of all RNA. It has a short chain of nucleotides in the form of a trefoil and is found in the cytoplasm. At one end of the shamrock is a triplet of nucleotides (anticodon) that codes for a specific amino acid. At the other end is a triplet of nucleotides to which an amino acid is attached. Each amino acid has its own tRNA. tRNA carries amino acids to the site of protein synthesis, i.e. to ribosomes (Fig. 35).

RNA is found in the nucleolus, cytoplasm, ribosomes, mitochondria, and plastids.

ATP - Adenazine triphosphoric acid. Adenazine triphosphoric acid (ATP) consists of a nitrogenous base - adenine, sugar - ribose, And three residues of phosphoric acid(Fig. 36). The ATP molecule accumulates a large amount of energy necessary for the biochemical processes taking place in the cell. ATP synthesis occurs in mitochondria. The ATP molecule is very unstable

chiva and is able to split off one or two molecules of phosphate with the release of a large amount of energy. The bonds in the ATP molecule are called macroergic.

ATP → ADP + P + 40 kJ ADP → AMP + P + 40 kJ

Rice. 35. The structure of tRNA.

A, B, C and D - sections of a complementary compound within one RNA chain; D - site (active center) of the compound with the amino acid; E - site of complementary connection with a molecule.

Rice. 36.The structure of ATP and its conversion to ADP.

Questions for self-control

1. What substances in the cell are classified as inorganic?

2. What substances in the cell are classified as organic?

3. What is a carbohydrate monomer?

4. What is the structure of carbohydrates?

5. What functions do carbohydrates perform?

6. What is the monomer of fats?

7. What is the structure of fats?

8. What are the functions of fats?

9. What is a protein monomer? 10. What is the structure of proteins? 11. What structures do proteins have?

12. What happens during the denaturation of a protein molecule?

13. What are the functions of proteins?

14. What nucleic acids are known?

15. What is a nucleic acid monomer?

16. What is included in the DNA nucleotide?

17. What is the structure of an RNA nucleotide?

18. What is the structure of a DNA molecule?

19. What functions does the DNA molecule perform?

20. What is the structure of rRNA?

21. What is the structure of mRNA?

22. What is the structure of tRNA?

23. What are the functions of ribonucleic acids?

24. What is the structure of ATP?

25. What functions does ATP perform in the cell?

Key words of the topic "Chemical composition of cells"

nitrogenous base of albumin

amino acid group of an amino acid

amphoteric compounds

anticodon

bacteria

squirrels

biological activity biological catalyst

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water

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hydrophobic compounds

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glycosides

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glycerol

globule

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glucose

hormones

guanine

double helix deoxyribose denaturation disaccharide

dissociated state

DNA

unit of information living organism animal vital activity fatty acids adipose tissue fat-like substances fats

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mitochondria

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milk sugar

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uracil

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formula

phosphoric acid photosynthesis fructose function

chemical elements

chloroplasts

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cellulose

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cytosine

cytoplasm

quaternary structure ball

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elements

core

A cell is an elementary unit of a living thing that has all the characteristics of an organism: the ability to reproduce, grow, exchange substances and energy with the environment, irritability, and the constancy of chemical composition.
Macronutrients - elements, the amount of which in the cell is up to 0.001% of body weight. Examples are oxygen, carbon, nitrogen, phosphorus, hydrogen, sulfur, iron, sodium, calcium, etc.
Trace elements - elements, the amount of which in the cell is from 0.001% to 0.000001% of body weight. Examples are boron, copper, cobalt, zinc, iodine, etc.
Ultramicroelements are elements whose content in the cell does not exceed 0.000001% of body weight. Examples are gold, mercury, cesium, selenium, etc.

2. Make a diagram of "Cell Substances".

3. What is he talking about scientific fact elementary similarities chemical composition animate and inanimate nature?
This indicates the commonality of animate and inanimate nature.

inorganic substances. The role of water and minerals in the life of the cell.
1. Give definitions of concepts.
Inorganic substances are water, mineral salts, acids, anions and cations present in both living and non-living organisms.
Water is one of the most common inorganic substances in nature, the molecule of which consists of two hydrogen atoms and one oxygen atom.

2. Draw a diagram of the structure of water.

3. What features of the structure of water molecules give it unique properties without which life is impossible?
The structure of the water molecule is formed by two hydrogen atoms and one oxygen atom, which form a dipole, that is, water has two polarities "+" and "-". This contributes to its permeability through the membrane walls, the ability to dissolve chemical substances. In addition, water dipoles are hydrogen bonded to each other, which ensures its ability to be in various states of aggregation, as well as to dissolve or not dissolve various substances.

4. Fill in the table "The role of water and minerals in the cell."

5. What is the meaning of relative constancy internal environment cells in ensuring the processes of its vital activity?
The constancy of the internal environment of the cell is called homeostasis. Violation of homeostasis leads to damage to the cell or to its death, plastic metabolism and energy metabolism constantly occur in the cell, these are two components of metabolism, and violation of this process leads to damage or death of the whole organism.

6. What is the purpose of the buffer systems of living organisms and what is the principle of their functioning?
Buffer systems maintain a certain pH value (acidity index) of the medium in biological fluids. The principle of operation is that the pH of the medium depends on the concentration of protons in this medium (H+). The buffer system is capable of absorbing or donating protons depending on their entry into the medium from outside or, on the contrary, removal from the medium, while the pH will not change. The presence of buffer systems is necessary in a living organism, since pH can change greatly due to changes in environmental conditions, and most enzymes work only at a certain pH value.
Examples of buffer systems:
carbonate-hydrocarbonate (mixture of Na2CO3 and NaHCO3)
phosphate (a mixture of K2HPO4 and KH2PO4).

organic substances. The role of carbohydrates, lipids and proteins in the life of the cell.
1. Give definitions of concepts.
Organic substances are substances that necessarily include carbon; they are part of living organisms and are formed only with their participation.
Proteins are high-molecular organic substances consisting of alpha-amino acids connected in a chain by a peptide bond.
Lipids are a broad group of natural organic compounds, including fats and fat-like substances. Simple lipid molecules consist of alcohol and fatty acids, complex lipids consist of alcohol, high molecular weight fatty acids and other components.
Carbohydrates are organic substances that contain carbonyl and several hydroxyl groups and are otherwise called sugars.

2. Enter in the table the missing information "Structure and functions of the organic substances of the cell."

3. What is meant by protein denaturation?
Protein denaturation is the loss of a protein's natural structure.

Nucleic acids, ATP and others organic compounds cells.
1. Give definitions of concepts.
Nucleic acids are biopolymers consisting of monomers - nucleotides.
ATP is a compound composed of the nitrogenous base adenine, a ribose carbohydrate, and three phosphoric acid residues.
A nucleotide is a nucleic acid monomer that consists of a phosphate group, a five-carbon sugar (pentose), and a nitrogenous base.
A macroergic bond is a bond between phosphoric acid residues in ATP.
Complementarity is the spatial mutual correspondence of nucleotides.

2. Prove that nucleic acids are biopolymers.
Nucleic acids are made up of a large number of repeating nucleotides and have a mass of 10,000 to several million carbon units.

3. Describe the structural features of the nucleotide molecule.
A nucleotide is a compound of three components: a phosphoric acid residue, a five-carbon sugar (ribose), and one of the nitrogenous compounds (adenine, guanine, cytosine, thymine, or uracil).

4. What is the structure of a DNA molecule?
DNA is a double helix consisting of many nucleotides that are sequentially connected to each other due to covalent bonds between the deoxyribose of one and the phosphoric acid residue of another nucleotide. The nitrogenous bases, which are located on one side of the backbone of one chain, are connected by H-bonds with the nitrogenous bases of the second chain according to the principle of complementarity.

5. Using the principle of complementarity, build the second strand of DNA.
T-A-T-C-A-G-A-C-C-T-A-C
A-T-A-G-T-C-T-G-G-A-T-G.

6. What are the main functions of DNA in a cell?
With the help of four types of nucleotides in DNA, all the important information in a cell about an organism is recorded, which is transmitted to subsequent generations.

7. How does an RNA molecule differ from a DNA molecule?
RNA is a single strand smaller than DNA. Nucleotides contain the sugar ribose, not deoxyribose, as in DNA. The nitrogenous base, instead of thymine, is uracil.

8. What is common in the structure of DNA and RNA molecules?
Both RNA and DNA are biopolymers made up of nucleotides. In nucleotides, the common structure is the presence of a phosphoric acid residue and adenine, guanine, and cytosine bases.

9. Fill in the table "RNA types and their functions in the cell."

10. What is ATP? What is its role in the cell?
ATP - adenosine triphosphate, macroergic compound. Its functions are the universal keeper and carrier of energy in the cell.

11. What is the structure of the ATP molecule?
ATP is made up of three residues of phosphoric acid, ribose, and adenine.

12. What are vitamins? For which two large groups do they share?
Vitamins are biologically active organic compounds that play an important role in metabolic processes. They are divided into water-soluble (C, B1, B2, etc.) and fat-soluble (A, E, etc.).

13. Fill in the table "Vitamins and their role in the human body."

Water. Of the inorganic substances that make up the cell, water is the most important. Its amount is from 60 to 95% of the total mass of the cell. Water plays an essential role in the life of cells and living organisms in general. In addition to being part of their composition, for many organisms it is also a habitat.

The role of water in the cell is determined by its unique chemical and physical properties, mainly related to the small size of the molecules, the polarity of its molecules and their ability to form hydrogen bonds with each other.

Water as a component of biological systems performs the following important functions:

1. Water- universal solvent for polar substances, such as salts, sugars, alcohols, acids, etc. Substances that are highly soluble in water are called hydrophilic. When a substance goes into solution, its molecules or ions are allowed to move more freely; the reactivity of the substance increases accordingly. It is for this reason that most of the chemical reactions in the cell proceed in aqueous solutions. Its molecules are involved in many chemical reactions, for example, during the formation or hydrolysis of polymers. In the process of photosynthesis, water is an electron donor, a source of hydrogen ions and free oxygen.
2. Water does not dissolve or mix with non-polar substances, since it cannot form hydrogen bonds with them. Substances that are insoluble in water are called hydrophobic. Hydrophobic molecules or their parts are repelled by water, and in its presence are attracted to each other. Such interactions play an important role in ensuring the stability of membranes, as well as many protein molecules, nucleic acids, and a number of subcellular structures.
3. Water has a high specific heat capacity. It takes a lot of energy to break the hydrogen bonds that hold water molecules together. This property ensures the maintenance of the thermal balance of the body with significant temperature fluctuations in environment. In addition, water is different high thermal conductivity, which allows the body to maintain the same temperature throughout its volume.
4. Water is characterized high heat of vaporization, T. That is, the ability of molecules to carry away with them a significant amount of heat while cooling the body. Due to this property of water, which is manifested during sweating in mammals, thermal shortness of breath in crocodiles and other animals, transpiration in plants, their overheating is prevented.
5. Water is exclusively high surface tension. This property is very important for adsorption processes, for the movement of solutions through tissues (blood circulation, ascending and descending currents in plants). For many small organisms, surface tension allows them to float or glide across the surface of the water.
6. Water provides movement of substances in the cell and the body, the absorption of substances and the excretion of metabolic products.
7. In plants, water determines turgor cells, and in some animals performs support functions being a hydrostatic skeleton (round and annelids, echinoderms).
8. Water is an integral part lubricating fluids(synovial - in the joints of vertebrates, pleural - in the pleural cavity, pericardial - in the pericardial sac) and slime(facilitate the movement of substances through the intestines, create a humid environment on the mucous membranes respiratory tract). It is part of saliva, bile, tears, sperm, etc.

mineral salts. Inorganic substances in the cell, other than water, precspavlevy mineral salts. Molecules of salts in an aqueous solution decompose into cations and anions. Highest value have cations (K +, Na +, Ca 2+, Mg: +, NH 4 +) and anions (C1, H 2 P0 4 -, HP0 4 2-, HC0 3 -, NO3 2--, SO 4 2- ) Not only the content, but also the ratio of ions in the cell is essential.

The difference between the number of cations and anions on the surface and inside the cell provides the occurrence action potential, what underlies the emergence of nervous and muscular excitation. The difference in the concentration of ions on different sides of the membrane is due to the active transfer of substances through the membrane, as well as the conversion of energy.

Biology [A complete guide to preparing for the exam] Lerner Georgy Isaakovich

2.3.1. Inorganic substances of the cell

The cell contains about 70 elements. periodic system elements of Mendeleev, and 24 of them are present in all types of cells. All elements present in the cell are divided, depending on their content in the cell, into groups:

macronutrients– H, O, N, C,. Mg, Na, Ca, Fe, K, P, Cl, S;

trace elements– B, Ni, Cu, Co, Zn, Mb, etc.;

ultramicroelements– U, Ra, Au, Pb, Hg, Se, etc.

The cell contains molecules inorganic And organic connections.

Inorganic compounds of the cell - water And inorganic ions.

Water is the most important inorganic substance of the cell. All biochemical reactions take place in aqueous solutions. The water molecule has a non-linear spatial structure and has polarity. Hydrogen bonds are formed between individual water molecules, which determine the physical and Chemical properties water.

Physical properties of water: Since water molecules are polar, water has the property of dissolving polar molecules of other substances. Substances that are soluble in water are called hydrophilic. Substances that are insoluble in water are called hydrophobic.

Water has a high specific heat. To break the numerous hydrogen bonds that exist between water molecules, it is necessary to absorb a large amount of energy. Remember how long it takes for a kettle to boil. This property of water ensures the maintenance of heat balance in the body.

It takes a lot of energy to evaporate water. The boiling point of water is higher than that of many other substances. This property of water protects the body from overheating.

Water can be in three states of aggregation - liquid, solid and gaseous.

Hydrogen bonds determine the viscosity of water and the adhesion of its molecules to the molecules of other substances. Due to the forces of adhesion of molecules, a film is created on the surface of the water, which has such a characteristic as surface tension.

When cooled, the movement of water molecules slows down. The number of hydrogen bonds between molecules becomes maximum. Water reaches its highest density at 4 C?. As water freezes, it expands (requires room for hydrogen bonds to form) and its density decreases. That's why ice floats.

Biological functions of water. Water ensures the movement of substances in the cell and body, the absorption of substances and the excretion of metabolic products. In nature, water carries waste products to soils and water bodies.

Water is an active participant in metabolic reactions.

Water is involved in the formation of lubricating fluids and mucus, secrets and juices in the body. These fluids are found in the joints of vertebrates, in the pleural cavity, in the pericardial sac.

Water is part of the mucus, which facilitate the movement of substances through the intestines, create a humid environment on the mucous membranes of the respiratory tract. water base they also have secrets secreted by certain glands and organs: saliva, tears, bile, sperm, etc.

inorganic ions. The inorganic ions of the cell include: cations K +, Na +, Ca 2+, Mg 2+, NH 3 + and anions Cl -, NO 3 -, H 2 PO 4 -, NCO 3 -, HPO 4 2-.

The difference between the number of cations and anions (Na + , Ka + , Cl -) on the surface and inside the cell provides the emergence of an action potential, which underlies the nervous and muscle excitation.

Anions phosphoric acids create phosphate buffer system, maintaining the pH of the intracellular environment of the body at the level of 6-9.

Carbonic acid and its anions create a bicarbonate buffer system and maintain the pH of the extracellular medium (blood plasma) at the level of 7-4.

Nitrogen compounds serve as a source of mineral nutrition, synthesis of proteins, nucleic acids. Phosphorus atoms are part of the nucleic acids, phospholipids, as well as the bones of vertebrates, the chitinous cover of arthropods. Calcium ions are part of the bone substance; they are also necessary for the implementation of muscle contraction, blood clotting.

EXAMPLES OF TASKS

A1. The polarity of water determines its ability

1) conduct heat 3) dissolve sodium chloride

2) absorb heat 4) dissolve glycerin

A2. Children with rickets should be given drugs containing

1) iron 2) potassium 3) calcium 4) zinc

A3. Conduction of a nerve impulse is provided by ions:

1) potassium and sodium 3) iron and copper

2) phosphorus and nitrogen 4) oxygen and chlorine

A4. Weak bonds between water molecules in its liquid phase are called:

1) covalent 3) hydrogen

2) hydrophobic 4) hydrophilic

A5. Hemoglobin contains

1) phosphorus 2) iron 3) sulfur 4) magnesium

A6. Choose a group of chemical elements that must be part of proteins

A7. Patients with hypothyroidism are given medications containing

Part B

IN 1. Select the functions of the water in the cage

1) energy 4) construction

2) enzymatic 5) lubricating

3) transport 6) thermoregulatory

AT 2. Select only physical properties water

1) the ability to dissociate

2) hydrolysis of salts

3) density

4) thermal conductivity

5) electrical conductivity

6) electron donation

Part WITH

C1. What physical properties of water determine its biological significance?

From the book Great Soviet Encyclopedia (VK) of the author TSB

From the book Great Soviet Encyclopedia (IN) of the author TSB

From the book Great Soviet Encyclopedia (KA) of the author TSB

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From the book Great Soviet Encyclopedia (PL) of the author TSB

From the book Great Soviet Encyclopedia (PO) of the author TSB

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