Elements included in the composition of body cells. What chemical elements make up the cell. Carbohydrates and polysaccharides include

Depending on the content chemical elements in the cell they are divided into groups: macroelements, microelements and ultramicroelements.

A separate group among macroelements consists of organogenic elements(O, C, H, N), which form the molecules of all organic substances.

Macroelements, their role in the cell.Organogenic elements - oxygen, carbon, hydrogen and nitrogen make up ≈98% of the cell's chemical content. They easily form covalent bonds by sharing two electrons (one from each atom) and thereby form a wide variety of organic substances in the cell.

Other macroelements in animal and human cells (potassium, sodium, magnesium, calcium, chlorine, iron) are also vital, accounting for about 1.9%.

Thus, Potassium and Sodium ions regulate osmotic pressure in the cell, determine the normal rhythm of cardiac activity, the occurrence and conduction of a nerve impulse. Calcium ions take part in blood clotting and muscle fiber contraction. Insoluble calcium salts take part in the formation of bones and teeth.

Magnesium ions play an important role in the functioning of ribosomes and mitochondria. Iron is part of hemoglobin.

Microelements, their role in the cell. The biological role of micro- and ultramicroelements is determined not by their percentage content, but by the fact that they are part of enzymes, vitamins and hormones. For example, Cobalt is part of vitamin B12, Iodine is part of the hormone thyroxine, Copper is part of enzymes that catalyze redox processes.

Ultramicroelements, their role in the cell. Their concentration does not exceed 0.000001%. These are the following elements: gold, silver, lead, uranium, selenium, cesium, beryllium, radium, etc. The physiological role of many chemical elements has not yet been established, but they are necessary for the normal functioning of the body. For example, deficiency of the ultramicroelement Selenium leads to the development of cancer.

Summarized information about the biological significance of the main chemical elements contained in the cells of living organisms is presented in Table 4.1.

When there is a shortage of an important chemical element in the soil of a certain region, which causes its deficiency in the body local residents, so-called endemic diseases.

All chemical elements are contained in the cell in the form of ions or are part of chemicals.

Table 4.1. Basic chemical elements of the cell and their significance for the life and activity of organisms

Element	Symbol	Content	Importance for cells and organisms
Carbon	o	15-18
Oxygen	N	65-75 1,5-3,0	Main structural component all organic compounds of the cell
Nitrogen	H	8-10	Essential component of amino acids
Hydrogen	K	0.0001	The main structural component of all organic compounds of the cell
Phosphorus	S	0,15-0,4	Part of bone tissue and tooth enamel, nucleic acids, ATP and some enzymes
Potassium	Cl	0,15-0,20	Contained in the cell only in the form of ions, activates enzymes of protein synthesis, determines the rhythm of cardiac activity, and participates in the processes of photosynthesis
Sulfur	Ca	0,05-0,10	Part of some amino acids, enzymes, vitamin B
Chlorine	Mg	0,04-2,00	The most important negative ion in the animal body, a component of HC1 in gastric juice
Calcium	Na	0,02-0,03	Part of the cell wall of plants, bones and teeth, activates blood clotting and muscle fiber contraction
Magnesium	Fe	0,02-0,03	Part of chlorophyll molecules, as well as bones and teeth, it activates energy metabolism and DNA synthesis
Sodium	I	0,010-0,015	Contained in the cell only in the form of ions, it determines the normal rhythm of cardiac activity and affects the synthesis of hormones
Iron	Cu	0,0001	Part of many enzymes, hemoglobin and myoglobin, participates in the biosynthesis of chlorophyll, in the processes of respiration and photosynthesis
Iodine	Mn	0,0002	Contains thyroid hormones
Copper	Mo	0.0001	It is part of some enzymes and participates in the processes of blood formation, photosynthesis, and hemoglobin synthesis.
Manganese	Co	0,0001	It is part of some enzymes or increases their activity, takes part in bone development, nitrogen assimilation and the process of photosynthesis
Molybdenum	Zn	0.0001	It is part of some enzymes and participates in the processes of fixing atmospheric nitrogen by plants.
Cobalt	o	0,0003	Part of vitamin B12, participates in the fixation of atmospheric nitrogen by plants and the development of red blood cells
Zinc	N	15-18	Part of some enzymes, participates in the synthesis of plant hormones (fuchsin) and alcoholic fermentation

Cell chemicals

The chemical composition of a cell is closely related to the structural features and functioning of this elementary and functional unit of living things. As in morphological terms, the most common and universal for cells of representatives of all kingdoms is chemical composition protoplast. The latter contains about 80% water, 10% organic matter and 1% salts. Among them, proteins, nucleic acids, lipids and carbohydrates play a leading role in the formation of a protoplast.

The composition of the chemical elements of the protoplast is extremely complex. It contains substances with both small molecular weight and substances with large molecules. 80% of the weight of the protoplast is made up of high molecular weight substances and only 30% is accounted for by low molecular weight compounds. At the same time, for each macromolecule there are hundreds, and for each large macromolecule there are thousands and tens of thousands of molecules.

Any cell contains more than 60 elements from the periodic table.

Based on frequency of occurrence, elements can be divided into three groups:

Inorganic substances have low molecular weight and are found and synthesized both in living cells and in inanimate nature. In the cell, these substances are represented mainly by water and salts dissolved in it.

Water makes up about 70% of the cell. Due to its special property of molecular polarization, water plays a huge role in the life of a cell.

A water molecule consists of two hydrogen atoms and one oxygen atom.

The electrochemical structure of the molecule is such that oxygen has a slight excess of negative charge, and hydrogen atoms have a positive charge, that is, a water molecule has two parts that attract other water molecules with oppositely charged parts. This leads to an increase in the connection between molecules, which in turn determines the liquid state of aggregation at temperatures from 0 to 1000C, despite the relatively low molecular weight. At the same time, polarized water molecules provide better solubility of salts.

The role of water in the cell:

· Water is the medium of the cell; all biochemical reactions take place in it.

· Water performs a transport function.

· Water is a solvent for inorganic and some organic substances.

· Water itself participates in some reactions (for example, photolysis of water).

Salts are found in the cell, usually in dissolved form, that is, in the form of anions (negatively charged ions) and cations (positively charged ions).

The most important anions of the cell are hydroskid (OH -), carbonate (CO 3 2-), bicarbonate (CO 3 -), phosphate (PO 4 3-), hydrophosphate (HPO 4 -), dihydrogen phosphate (H 2 PO 4 -). The role of anions is enormous. Phosphate ensures the formation of high-energy bonds (chemical bonds with high energy). Carbonates provide buffering properties of the cytoplasm. Buffer capacity is the ability to maintain constant acidity of a solution.

The most important cations include proton (H +), potassium (K +), sodium (Na +). The proton is involved in many biochemical reactions, and its concentration also determines such an important characteristic of the cytoplasm as its acidity. Potassium and sodium ions provide such an important property of the cell membrane as the conductivity of an electrical impulse.

The cell is the elementary structure in which all the main stages of biological metabolism are carried out and contains all the main chemical components of living matter. 80% of the weight of the protoplast consists of high-molecular substances - proteins, carbohydrates, lipids, nucleic acids, ATP. The organic substances of the cell are represented by various biochemical polymers, that is, molecules that consist of numerous repetitions of simpler sections (monomers) similar in structure.

2. Organic substances, their structure and role in the life of the cell.

About 70 elements of D.I. Mendeleev’s periodic system of elements were found in the cells of different organisms, but only 24 of them have a well-established significance and are constantly found in all types of cells.

The largest share in the elemental composition of the cell is made up of oxygen, carbon, hydrogen and nitrogen. These are the so-called basic or nutrients. These elements account for more than 95% of the mass of cells, and their relative content in living matter is much higher than in the earth’s crust. Calcium, phosphorus, sulfur, potassium, chlorine, sodium, magnesium, iodine and iron are also vital. Their content in the cell is calculated in tenths and hundredths of a percent. The listed elements form a group macronutrients.

Other chemical elements: copper, manganese, molybdenum, cobalt, zinc, boron, fluorine, chromium, selenium, aluminum, iodine, iron, silicon - are contained in extremely small quantities (less than 0.01% of cell mass). They belong to the group microelements.

The percentage content of a particular element in the body in no way characterizes the degree of its importance and necessity in the body. For example, many microelements are part of various biologically active substances - enzymes, vitamins (cobalt is part of vitamin B 12), hormones (iodine is part of thyroxine); they influence the growth and development of organisms (zinc, manganese, copper) , hematopoiesis (iron, copper), cellular respiration processes (copper, zinc), etc. The content and significance of various chemical elements for the life of cells and the body as a whole are given in the table:

The most important chemical elements of the cell

Element	Symbol	Approximate content, %	Importance for cells and organisms
Oxygen	O	62	Part of water and organic matter; participates in cellular respiration
Carbon	C	20	Contains all organic substances
Hydrogen	H	10	Part of water and organic matter; participates in energy conversion processes
Nitrogen	N	3	Contains amino acids, proteins, nucleic acids, ATP, chlorophyll, vitamins
Calcium	Ca	2,5	Part of the cell wall of plants, bones and teeth, increases blood clotting and contractility of muscle fibers
Phosphorus	P	1,0	Part of bone tissue and tooth enamel, nucleic acids, ATP, and some enzymes
Sulfur	S	0,25	Part of amino acids (cysteine, cystine and methionine), some vitamins, participates in the formation of disulfide bonds in the formation of the tertiary structure of proteins
Potassium	K	0,25	Contained in the cell only in the form of ions, activates enzymes of protein synthesis, determines the normal rhythm of cardiac activity, participates in the processes of photosynthesis and the generation of bioelectric potentials
Chlorine	Cl	0,2	The negative ion predominates in the body of animals. Hydrochloric acid component of gastric juice
Sodium	Na	0,10	Contained in the cell only in the form of ions, it determines the normal rhythm of cardiac activity and affects the synthesis of hormones
Magnesium	Mg	0,07	Part of chlorophyll molecules, as well as bones and teeth, activates energy metabolism and DNA synthesis
Iodine	I	0,01	Contains thyroid hormones
Iron	Fe	0,01	It is part of many enzymes, hemoglobin and myoglobin, participates in the biosynthesis of chlorophyll, in electron transport, in the processes of respiration and photosynthesis
Copper	Cu	Traces	It is part of hemocyanins in invertebrates, part of some enzymes, and is involved in the processes of hematopoiesis, photosynthesis, and hemoglobin synthesis.
Manganese	Mn	Traces	Part of or increases the activity of certain enzymes, participates in bone development, nitrogen assimilation and the process of photosynthesis
Molybdenum	Mo	Traces	Part of some enzymes (nitrate reductase), participates in the processes of fixation of atmospheric nitrogen by nodule bacteria
Cobalt	Co	Traces	Part of vitamin B 12, participates in the fixation of atmospheric nitrogen by nodule bacteria
Bor	B	Traces	Affects plant growth processes, activates reductive respiration enzymes
Zinc	Zn	Traces	Part of some enzymes that break down polypeptides, participates in the synthesis of plant hormones (auxins) and glycolysis
Fluorine	F	Traces	Contains the enamel of teeth and bones

The composition of a living cell includes the same chemical elements that are part of inanimate nature. Of the 104 elements of D. I. Mendeleev’s periodic table, 60 were found in cells.

They are divided into three groups:

1. the main elements are oxygen, carbon, hydrogen and nitrogen (98% of the cell composition);
2. elements constituting tenths and hundredths of a percent - potassium, phosphorus, sulfur, magnesium, iron, chlorine, calcium, sodium (in total 1.9%);
3. all other elements present in even smaller quantities are microelements.

The molecular composition of a cell is complex and heterogeneous. Individual compounds - water and mineral salts - are also found in inanimate nature; others - organic compounds: carbohydrates, fats, proteins, nucleic acids, etc. - are characteristic only of living organisms.

INORGANIC SUBSTANCES

Water makes up about 80% of the cell's mass; in young fast-growing cells - up to 95%, in old cells - 60%.

The role of water in the cell is great.

It is the main medium and solvent, participates in most chemical reactions, the movement of substances, thermoregulation, the formation of cellular structures, and determines the volume and elasticity of the cell. Most substances enter and exit the body in an aqueous solution. The biological role of water is determined by the specificity of its structure: the polarity of its molecules and the ability to form hydrogen bonds, due to which complexes of several water molecules arise. If the energy of attraction between water molecules is less than between the molecules of water and a substance, it dissolves in water. Such substances are called hydrophilic (from the Greek “hydro” - water, “fillet” - love). These are many mineral salts, proteins, carbohydrates, etc. If the energy of attraction between water molecules is greater than the energy of attraction between molecules of water and a substance, such substances are insoluble (or slightly soluble), they are called hydrophobic (from the Greek “phobos” - fear) - fats, lipids, etc.

Mineral salts in aqueous cell solutions dissociate into cations and anions, providing a stable amount of necessary chemical elements and osmotic pressure. Of the cations, the most important are K +, Na +, Ca 2+, Mg +. The concentration of individual cations in the cell and in the extracellular environment is not the same. In a living cell, the concentration of K is high, Na + is low, and in the blood plasma, on the contrary, the concentration of Na + is high and K + is low. This is due to the selective permeability of membranes. The difference in the concentration of ions in the cell and the environment ensures the flow of water from the environment into the cell and the absorption of water by plant roots. The lack of individual elements - Fe, P, Mg, Co, Zn - blocks the formation of nucleic acids, hemoglobin, proteins and other vital substances and leads to serious diseases. Anions determine the constancy of the pH-cellular environment (neutral and slightly alkaline). Of the anions, the most important are HPO 4 2-, H 2 PO 4 -, Cl -, HCO 3 -

ORGANIC SUBSTANCES

Organic substances in the complex form about 20-30% of the cell composition.

Carbohydrates- organic compounds consisting of carbon, hydrogen and oxygen. They are divided into simple - monosaccharides (from the Greek "monos" - one) and complex - polysaccharides (from the Greek "poly" - many).

Monosaccharides(their general formula C n H 2n O n) are colorless substances with a pleasant sweet taste, highly soluble in water. They differ in the number of carbon atoms. Of the monosaccharides, the most common are hexoses (with 6 C atoms): glucose, fructose (found in fruits, honey, blood) and galactose (found in milk). Of the pentoses (with 5 C atoms), the most common are ribose and deoxyribose, which are part of nucleic acids and ATP.

Polysaccharides refer to polymers - compounds in which the same monomer is repeated many times. The monomers of polysaccharides are monosaccharides. Polysaccharides are water soluble and many have a sweet taste. Of these, the simplest are disaccharides, consisting of two monosaccharides. For example, sucrose consists of glucose and fructose; milk sugar - from glucose and galactose. As the number of monomers increases, the solubility of polysaccharides decreases. Of the high-molecular polysaccharides, glycogen is the most common in animals, and starch and fiber (cellulose) in plants. The latter consists of 150-200 glucose molecules.

Carbohydrates- the main source of energy for all forms of cellular activity (movement, biosynthesis, secretion, etc.). Breaking down into the simplest products CO 2 and H 2 O, 1 g of carbohydrate releases 17.6 kJ of energy. Carbohydrates perform a construction function in plants (their shells consist of cellulose) and the role of storage substances (in plants - starch, in animals - glycogen).

Lipids- These are water-insoluble fat-like substances and fats, consisting of glycerol and high-molecular fatty acids. Animal fats are found in milk, meat, and subcutaneous tissue. At room temperature they are solids. In plants, fats are found in seeds, fruits and other organs. At room temperature they are liquids. Fat-like substances are similar in chemical structure to fats. There are many of them in the yolk of eggs, brain cells and other tissues.

The role of lipids is determined by their structural function. They consist of cell membranes, which, due to their hydrophobicity, prevent the mixing of cell contents with environment. Lipids perform an energy function. Breaking down to CO 2 and H 2 O, 1 g of fat releases 38.9 kJ of energy. They conduct heat poorly, accumulating in the subcutaneous tissue (and other organs and tissues), perform protective function and the role of reserve substances.

Squirrels- the most specific and important for the body. They belong to non-periodic polymers. Unlike other polymers, their molecules consist of similar, but non-identical monomers - 20 different amino acids.

Each amino acid has its own name, special structure and properties. Their general formula can be represented as follows

An amino acid molecule consists of a specific part (radical R) and a part that is the same for all amino acids, including an amino group (- NH 2) with basic properties, and a carboxyl group (COOH) with acidic properties. The presence of acidic and basic groups in one molecule determines their high reactivity. Through these groups, amino acids are combined to form a polymer - protein. In this case, a water molecule is released from the amino group of one amino acid and the carboxyl of another, and the released electrons are combined to form a peptide bond. Therefore, proteins are called polypeptides.

A protein molecule is a chain of several tens or hundreds of amino acids.

Protein molecules are enormous in size, which is why they are called macromolecules. Proteins, like amino acids, are highly reactive and can react with acids and alkalis. They differ in composition, quantity and sequence of amino acids (the number of such combinations of 20 amino acids is almost infinite). This explains the diversity of proteins.

There are four levels of organization in the structure of protein molecules (59)

• Primary structure- a polypeptide chain of amino acids linked in a certain sequence by covalent (strong) peptide bonds.
• Secondary structure- a polypeptide chain twisted into a tight spiral. In it, low-strength hydrogen bonds arise between the peptide bonds of neighboring turns (and other atoms). Together they provide a fairly strong structure.
• Tertiary structure represents a bizarre, but specific configuration for each protein - a globule. It is held by low-strength hydrophobic bonds or adhesive forces between non-polar radicals, which are found in many amino acids. Due to their abundance, they provide sufficient stability of the protein macromolecule and its mobility. The tertiary structure of proteins is also maintained due to covalent S - S (es - es) bonds that arise between distant radicals of the sulfur-containing amino acid - cysteine.
• Quaternary structure not typical for all proteins. It occurs when several protein macromolecules combine to form complexes. For example, hemoglobin in human blood is a complex of four macromolecules of this protein.

This complexity of the structure of protein molecules is associated with the diversity of functions inherent in these biopolymers. However, the structure of protein molecules depends on the properties of the environment.

Violation of the natural structure of a protein is called denaturation. It can occur under the influence of heat, chemicals, radiant energy and other factors. With a weak impact, only the quaternary structure disintegrates, with a stronger impact, the tertiary, and then the secondary, and the protein remains in the form of a primary structure - a polypeptide chain. This process is partially reversible, and the denatured protein is able to restore its structure.

The role of protein in the life of a cell is enormous.

Squirrels- This building material body. They participate in the construction of the shell, organelles and membranes of the cell and individual tissues (hair, blood vessels, etc.). Many proteins act as catalysts in the cell - enzymes that accelerate cellular reactions tens or hundreds of millions of times. About a thousand enzymes are known. In addition to protein, their composition includes metals Mg, Fe, Mn, vitamins, etc.

Each reaction is catalyzed by its own specific enzyme. In this case, it is not the entire enzyme that acts, but a certain region - the active center. It fits into the substrate like a key into a lock. Enzymes operate at a certain temperature and pH of the environment. Special contractile proteins provide the motor functions of cells (movement of flagella, ciliates, muscle contraction, etc.). Individual proteins (blood hemoglobin) perform a transport function, delivering oxygen to all organs and tissues of the body. Specific proteins - antibodies - perform a protective function, neutralizing foreign substances. Some proteins perform an energy function. Breaking down into amino acids and then into even simpler substances, 1 g of protein releases 17.6 kJ of energy.

Nucleic acids(from the Latin “nucleus” - core) were first discovered in the nucleus. They are of two types - deoxyribonucleic acids(DNA) and ribonucleic acids(RNA). Their biological role is great; they determine the synthesis of proteins and the transfer of hereditary information from one generation to another.

The DNA molecule has a complex structure. It consists of two spirally twisted chains. The width of the double helix is ​​2 nm 1, the length is several tens and even hundreds of micromicrons (hundreds or thousands of times larger than the largest protein molecule). DNA is a polymer whose monomers are nucleotides - compounds consisting of a molecule of phosphoric acid, a carbohydrate - deoxyribose and a nitrogenous base. Their general formula is as follows:

Phosphoric acid and carbohydrate are the same in all nucleotides, and nitrogenous bases are of four types: adenine, guanine, cytosine and thymine. They determine the name of the corresponding nucleotides:

• adenyl (A),
• guanyl (G),
• cytosyl (C),
• thymidyl (T).

Each DNA strand is a polynucleotide consisting of several tens of thousands of nucleotides. In it, neighboring nucleotides are connected by a strong covalent bond between phosphoric acid and deoxyribose.

Given the enormous size of DNA molecules, the combination of four nucleotides in them can be infinitely large.

When a DNA double helix is ​​formed, the nitrogenous bases of one chain are arranged in a strictly defined order opposite the nitrogenous bases of the other. In this case, T is always against A, and only C is against G. This is explained by the fact that A and T, as well as G and C, strictly correspond to each other, like two halves broken glass, and are additional or complementary(from the Greek “complement” - addition) to each other. If the sequence of nucleotides in one DNA chain is known, then using the principle of complementarity it is possible to determine the nucleotides of another chain (see Appendix, task 1). Complementary nucleotides are connected using hydrogen bonds.

There are two connections between A and T, and three between G and C.

The doubling of the DNA molecule is its unique feature, which ensures the transfer of hereditary information from the mother cell to the daughter cells. The process of DNA doubling is called DNA reduplication. It is carried out as follows. Shortly before cell division, the DNA molecule unwinds and its double strand, under the action of an enzyme, is split at one end into two independent chains. On each half of the free nucleotides of the cell, according to the principle of complementarity, a second chain is built. As a result, instead of one DNA molecule, two completely identical molecules appear.

RNA- a polymer similar in structure to one strand of DNA, but much smaller in size. RNA monomers are nucleotides consisting of phosphoric acid, a carbohydrate (ribose) and a nitrogenous base. Three nitrogenous bases of RNA - adenine, guanine and cytosine - correspond to those of DNA, but the fourth is different. Instead of thymine, RNA contains uracil. The formation of an RNA polymer occurs through covalent bonds between ribose and phosphoric acid of neighboring nucleotides. Three types of RNA are known: messenger RNA(i-RNA) transmits information about the structure of the protein from the DNA molecule; transfer RNA(tRNA) transports amino acids to the site of protein synthesis; ribosomal RNA (r-RNA) is contained in ribosomes and is involved in protein synthesis.

ATP- adenosine triphosphoric acid is an important organic compound. Its structure is a nucleotide. It consists of the nitrogenous base adenine, the carbohydrate ribose and three molecules of phosphoric acid. ATP is an unstable structure, under the influence of the enzyme the bond between “P” and “O” is broken, a molecule of phosphoric acid is split off and ATP goes into

>> Chemistry: Chemical elements in the cells of living organisms

More than 70 elements have been discovered in the substances that form the cells of all living organisms (humans, animals, plants). These elements are usually divided into two groups: macroelements and microelements.

Macroelements are found in cells in large quantities. First of all, these are carbon, oxygen, nitrogen and hydrogen. Together they make up almost 98% of the total contents of the cell. In addition to these elements, macroelements also include magnesium, potassium, calcium, sodium, phosphorus, sulfur and chlorine. Their total content is 1.9%. Thus, the share of other chemical elements accounts for about 0.1%. These are microelements. These include iron, zinc, manganese, boron, copper, iodine, cobalt, bromine, fluorine, aluminum, etc.

23 microelements were found in mammalian milk: lithium, rubidium, copper, silver, barium, strontium, titanium, arsenic, vanadium, chromium, molybdenum, iodine, fluorine, manganese, iron, cobalt, nickel, etc.

The blood of mammals contains 24 trace elements, and the human brain contains 18 trace elements.

As you can see, in the cell there are no special elements characteristic only of living nature, that is, at the atomic level there are no differences between living and inanimate nature. These differences are found only at the level of complex substances - at the molecular level. Thus, along with inorganic substances (water and mineral salts), the cells of living organisms contain substances characteristic only of them - organic substances (proteins, fats, carbohydrates, nucleic acids, vitamins, hormones, etc.). These substances are built mainly from carbon, hydrogen, oxygen and nitrogen, i.e. from macroelements. Microelements are contained in these substances in small quantities, however, their role in the normal functioning of organisms is enormous. For example, compounds of boron, manganese, zinc, and cobalt dramatically increase the yield of individual agricultural plants and increase their resistance to various diseases.

Humans and animals receive the microelements they need for normal life through the plants they eat. If there is not enough manganese in food, then growth retardation, delayed puberty, and metabolic disorders during the formation of the skeleton are possible. Adding fractions of a milligram of manganese salts to the daily diet of animals eliminates these diseases.

Cobalt is part of vitamin B12, which is responsible for the functioning of blood-forming organs. Lack of cobalt in food often causes serious illness, which leads to depletion of the body and even death.

The importance of microelements for humans was first revealed during the study of a disease such as endemic goiter, which was caused by a lack of iodine in food and water. Taking salt containing iodine leads to recovery, and adding it to food in small quantities prevents disease. For this purpose, table salt is iodized, to which 0.001-0.01% potassium iodide is added.

Most biological enzyme catalysts include zinc, molybdenum and some other metals. These elements, contained in very small quantities in the cells of living organisms, ensure the normal functioning of the finest biochemical mechanisms and are true regulators of vital processes.

Many microelements are contained in vitamins - organic substances of various chemical natures that enter the body with food in small doses and have a great impact on metabolism and the overall functioning of the body. In their biological action, they are close to enzymes, but enzymes are formed by the cells of the body, and vitamins usually come from food. Sources of vitamins are plants: citrus fruits, rose hips, parsley, onions, garlic and many others. Some vitamins - A, B1, B2, K - are obtained synthetically. Vitamins got their name from two words: vita - life and amine - containing nitrogen.

Microelements are also part of hormones - biologically active substances that regulate the functioning of organs and organ systems of humans and animals. They take their name from Greek word Harmao - I win. Hormones are produced by the endocrine glands and enter the blood, which carries them throughout the body. Some hormones are obtained synthetically.

1. Macroelements and microelements.

2. The role of microelements in the life of plants, animals and humans.

3. Organic substances: proteins, fats, carbohydrates.

4. Enzymes.

5. Vitamins.

6. Hormones.

At what level of forms of existence of a chemical element does the difference between living and inanimate nature begin?

Why are individual macroelements also called biogenic? List them.

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