mineral salts perform a variety of functions in the body. They are playing important role in plastic processes, the formation and construction of body tissues, regulate metabolism, acid-base balance and water exchange, participate in protein synthesis, various enzymatic processes, work endocrine glands. More than 60 out of 104 mineral elements known in nature have already been found in the human body. Minerals present in food products in significant amounts are called macronutrients. Among them, calcium, phosphorus, sodium and potassium have the greatest hygienic value.

Calcium is part of the bone tissue. It has a significant effect on the metabolism and work of the heart muscle, helps to increase defensive forces body, participates in the process of blood coagulation and has an anti-inflammatory effect. Calcium deficiency in the body adversely affects the processes of ossification, the function of the heart muscle and the course of a number of enzymatic processes. Daily rate calcium for adults 800 mg. Milk and dairy products (cottage cheese, cheese, sour cream) are especially rich in calcium.

Phosphorus, like calcium, is essential for bone formation. It plays an important role in the activity of the nervous system. Organic phosphorus compounds are consumed during muscle contraction, as well as in biochemical processes occurring in the brain, liver, kidneys and other organs. The daily norm of phosphorus is 1600 mg. The main sources of phosphorus: cheese, liver, eggs, meat, fish, beans, peas. To meet the body's need for calcium and phosphorus importance have conditions for their optimal assimilation. Calcium and phosphorus are well absorbed when the ratio between them is 1:1.5 (milk and dairy products, buckwheat porridge with milk).

Sodium is found in many organs, tissues and biological fluids organism. It plays an important role in the processes of intracellular and intercellular metabolism. sodium has great importance to maintain osmotic pressure in the blood and tissue fluids, as well as for water exchange. A person receives sodium mainly from table salt, which gives taste to food and stimulates appetite. V normal conditions the daily requirement for sodium chloride is 10-15 g. At high air temperatures, the body can lose a significant amount with sweat table salt. Therefore, when profuse sweating the need for it increases to 20-25 g.

Potassium is an indispensable bioelement for humans. The adult requirement for potassium is 2000-3000 mg per day and is mainly covered by the intake of plant foods and meat.

An important role in the life of the organism is also played by iron, cobalt, iodine, fluorine, bromine, potassium, chlorine, manganese, zinc. In the body and food, they are found in very small quantities. Minerals are contained and ingested with vegetables and fruits.

We must not forget about water. It is needed primarily for the introduction of solutions into the blood nutrients to be removed from the body unwanted products metabolism, as well as to regulate body temperature. daily requirement young body in water is 1-2.5 liters.

Lack of water leads to thickening of the blood, to a delay harmful products metabolism in tissues, to the violation of salt balance. Its excess is no better, also leading to a violation of the water-salt balance in the body, creating an excessive load on the heart and excretory organs.

We all know that to maintain the health of our body, proteins, carbohydrates, fats and, of course, water are needed. Mineral salts are also important component food, playing the role of participants metabolic processes, catalysts bio chemical reactions.

A significant part of the useful substances are chloride, carbonate, phosphate salts of sodium, calcium, potassium and magnesium. In addition to them, compounds of copper, zinc, iron, manganese, iodine, cobalt and other elements are present in the body. Useful material v aquatic environment dissolve and exist as ions.

Types of mineral salts

Salts can decompose into positive and negative ions. The former are called cations (charged particles of various metals), the latter are called anions. Negatively charged ions of phosphoric acid form a phosphate buffer system, the main significance of which is to regulate the pH of urine and interstitial fluid. Anions of carbonic acid form a bicarbonate buffer system, which is responsible for the activity of the lungs and maintains the pH of the blood plasma at the desired level. Thus, mineral salts, the composition of which is represented by various ions, have their own unique significance. For example, they participate in the synthesis of phospholipids, nucleotides, hemoglobin, ATP, chlorophyll, and so on.

The group of macronutrients includes sodium, magnesium, potassium, phosphorus, calcium and chlorine ions. These elements must be eaten in sufficient quantities. What is the importance of mineral salts of the macronutrient group? We'll figure out.

Salts of sodium and chlorine

One of the most common compounds that a person consumes every day is table salt. The substance is composed of sodium and chlorine. The first regulates the amount of fluid in the body, and the second, combining with a hydrogen ion, forms hydrochloric acid in the stomach. Sodium affects the growth of the body and the functioning of the heart. The lack of an element can lead to apathy and weakness, can cause hardening of the walls of the arteries, the formation gallstones and involuntary muscle twitching. Excess sodium chloride leads to the formation of edema. For a day you need to eat no more than 2 grams of salt.

Potassium salts

This ion is responsible for brain activity. The element helps to increase concentration, the development of memory. It maintains the excitability of muscle and nerve tissues, water-salt balance, arterial pressure. The ion also catalyzes the formation of acetylcholine and regulates osmotic pressure. With a deficiency of potassium salts, a person feels disorientation, drowsiness, reflexes are disturbed, and mental activity decreases. The element is found in many foods, such as vegetables, fruits, nuts.

Salts of calcium and phosphorus

The calcium ion is involved in the stabilization of the membranes of brain cells, as well as nerve cells. The element is responsible for the normal development of bones, is necessary for blood clotting, helps to eliminate lead and heavy metals from the body. The ion is the main source of blood saturation with alkaline salts, which contributes to the maintenance of life. Human glands that secrete hormones should normally always contain a sufficient amount of calcium ions, otherwise the body will begin to age prematurely. Children require this ion three times more than adults. Excess calcium can lead to kidney stones. Its deficiency causes cessation of breathing, as well as a significant deterioration in the work of the heart.

The phosphorus ion is responsible for the production of energy from nutrients. When it interacts with calcium and vitamin D, the functions of the brain and nerve tissues are activated. Phosphorus ion deficiency can delay bone development. It should be consumed no more than 1 gram per day. For the body, a favorable ratio of this element and calcium is one to one. An excess of phosphorus ions can cause various tumors.

Magnesium salts

Mineral salts in the cell break down into various ions, one of them is magnesium. The element is indispensable in protein, carbohydrate and fat metabolism. The magnesium ion is involved in the conduction of impulses along nerve fibers, stabilizes the cell membranes of nerve cells, thereby protecting the body from the effects of stress. The element regulates the work of the intestines. With a lack of magnesium, a person suffers from memory impairment, loses the ability to concentrate his attention for a long time, becomes irritable and nervous. It is enough to consume 400 milligrams of magnesium per day.

The group of trace elements includes ions of cobalt, copper, iron, chromium, fluorine, zinc, iodine, selenium, manganese and silicon. These elements are necessary for the body in minimal quantities.

Salts of iron, fluorine, iodine

The daily need for an iron ion is only 15 milligrams. This element is part of hemoglobin, which transports oxygen to tissues and cells from the lungs. Iron deficiency causes anemia.

Fluorine ions are present in tooth enamel, bones, muscles, blood and brain. With a lack of this element, the teeth lose their strength, begin to collapse. On the this moment the problem of fluorine deficiency is solved by using toothpastes containing it, as well as by eating a sufficient amount of foods rich in fluorine (nuts, cereals, fruits, and others).

Iodine is responsible for correct work thyroid gland, thereby regulating metabolism. With its deficiency, goiter develops and immunity decreases. With a lack of iodine ions in children, there is a delay in growth and development. An excess of element ions causes Basedow's disease, is also observed general weakness, irritability, weight loss, muscle atrophy.

Salts of copper and zinc

Copper, in cooperation with the iron ion, saturates the body with oxygen. Therefore, copper deficiency causes disturbances in the synthesis of hemoglobin, the development of anemia. Lack of an element can lead to various diseases of cardio-vascular system, appearance bronchial asthma and mental disorders. An excess of copper ions provokes CNS disorders. The patient complains of depression, memory loss, insomnia. An excess of the element is more common in the body of workers in the production of copper. In this case, the ions enter the body through inhalation of vapors, which leads to the phenomenon of copper fever. Copper can accumulate in the tissues of the brain, as well as in the liver, skin, pancreas, causing various disorders of the body. A person needs 2.5 milligrams of an element per day.

A number of properties of copper ions are associated with zinc ions. Together, they participate in the activity of the superoxide dismutase enzyme, which has antioxidant, antiviral, antiallergic and anti-inflammatory effects. Zinc ions are involved in protein and fat metabolism. It is part of most hormones and enzymes, controls the biochemical bonds between brain cells. Zinc ions fight alcohol intoxication.

According to some scientists, the deficiency of the element can cause fear, depression, impaired speech, and difficulty in movement. An excess of ion is formed by the uncontrolled use of preparations containing zinc, including ointments, as well as during work in the production of this element. A large amount of the substance leads to a decrease in immunity, impaired functions of the liver, prostate, pancreas.

The value of mineral salts containing copper and zinc ions cannot be overestimated. And, following the rules of nutrition, the listed problems associated with an excess or lack of elements can always be avoided.

Salts of cobalt and chromium

Mineral salts containing chromium ions play an important role in the regulation of insulin. The element is involved in the synthesis fatty acids, proteins, as well as in the process of glucose metabolism. A lack of chromium can cause an increase in the amount of cholesterol in the blood, and therefore increase the risk of a stroke.

One of the components of vitamin B 12 is the cobalt ion. He takes part in the production of thyroid hormones, as well as fats, proteins and carbohydrates, activates enzymes. Cobalt fights education atherosclerotic plaques, removing cholesterol from the vessels. This element is responsible for the production of RNA and DNA, promotes growth bone tissue, activates the synthesis of hemoglobin, is able to inhibit the development of cancer cells.

Athletes and vegetarians are often deficient in cobalt ions, which can lead to various violations in the body: anemia, arrhythmias, vegetative dystonia, memory disorders, etc. When vitamin B 12 is abused or when it comes into contact with this element at work, an excess of cobalt in the body occurs.

Salts of manganese, silicon and selenium

Three elements that are part of the micronutrient group also play an important role in maintaining the health of the body. So, manganese is involved in immune reactions, improves thinking processes, stimulates tissue respiration and hematopoiesis. The functions of mineral salts, in which silicon is present, are to give strength and elasticity to the walls of blood vessels. The element selenium in microdoses brings great benefits to humans. It is able to protect against cancer, supports the growth of the body, strengthens the immune system. With a lack of selenium, inflammation is formed in the joints, weakness in the muscles, the functioning of the thyroid gland is disrupted, male power, visual acuity decreases. daily requirement for given element is 400 micrograms.

Mineral exchange

What's Included this concept? This is a combination of the processes of absorption, assimilation, distribution, transformation and excretion. various substances. Mineral salts in the body create an internal environment with constant physical and chemical properties, which ensures the normal activity of cells and tissues.

Entering the digestive system with food, ions pass into the blood and lymph. The functions of mineral salts are to maintain the acid-base constancy of the blood, to regulate the osmotic pressure in the cells, as well as in the interstitial fluid. Useful substances take part in the formation of enzymes and in the process of blood clotting. Salts regulate total fluids in the body. Osmoregulation is based on the potassium-sodium pump. Potassium ions accumulate inside cells, and sodium ions accumulate in their environment. Due to the potential difference, the liquids are redistributed and thereby the constancy of the osmotic pressure is maintained.

Salts are excreted in three ways:

1. Through the kidneys. In this way, potassium, iodine, sodium and chlorine ions are removed.
2. Through the intestines. Salts of magnesium, calcium, iron and copper leave the body with feces.
3. Through the skin (along with sweat).

In order to avoid salt retention in the body, it is necessary to consume a sufficient amount of fluid.

Mineral metabolism disorders

The main reasons for deviations are:

1. hereditary factors. In this case, the exchange of mineral salts can be expressed in such a phenomenon as salt-sensitivity. The kidneys and adrenal glands in this disorder produce substances that can disrupt the content of potassium and sodium in the walls of blood vessels, thereby causing a water-salt imbalance.
2. Unfavorable ecology.
3. Eating too much salt.
4. Poor quality food.
5. Professional hazard.
6. Binge eating.
7. Excessive use of tobacco and alcohol.
8. age disorders.

Despite the small percentage in food, the role of mineral salts cannot be overestimated. Some of the ions are the building material of the skeleton, others are involved in the regulation of the water-salt balance, and others are involved in the accumulation and release of energy. Deficiency, as well as an excess of minerals, harms the body.

At daily use vegetable and animal food don't forget the water. Some food items such as seaweed, cereals, seafood, can incorrectly concentrate mineral salts in the cell, which is harmful to the body. For good digestibility, it is necessary to take breaks between taking the same salts for seven hours. Balanced diet is the key to the health of our body.

Mineral salts are among the necessary components of the food taken, and their absence can lead to the death of a living organism. They are very actively involved in the activities of all elements of the body, as well as in the normalization of the functioning of its systems. Minerals are necessary for hematopoiesis, the formation of various tissues. For example, calcium and phosphorus are the main structural elements of bone tissue. It is believed that a person needs at least twenty different mineral salts. In our body, they can come with water and food.

For some types of products, high concentration certain minerals, including rare ones. Cereals contain a lot of silicon, and marine plants - iodine.

For our body, a certain acid-gap balance is normal. Its maintenance is the basis of effective life activity. Such a balance should be constant, but with some shifts in nutrition, it can fluctuate in one direction or another.

For human nutrition, a shift towards an acidic character is considered characteristic. It is fraught with development various diseases including atherosclerosis.

To sour minerals include chlorine, phosphorus and sulfur. They are found in fish, meat, bread, eggs, cereals, etc. Potassium, sodium, magnesium and calcium are alkaline elements.

They are rich in products such as fruits and vegetables, berries, milk and its derivatives.
The older a person gets, the more alkaline products must be present in his diet.

The most essential mineral salts for our body are potassium, calcium, phosphorus, magnesium and iron.

Potassium belongs to the alkali metals. It is needed by our body to build muscles, as well as for the spleen and liver. Potassium contributes to the normalization of digestion processes, and in particular actively stimulates the processing of starches and fats.

This explains the benefits of this element for constipation. In addition, it is indispensable for disorders in blood circulation, inflammatory processes on the skin, weakened work of the heart and flushes of blood.

Shows up quickly muscle mass as well as violations mental activity. This element is contained in sour fruits, raw vegetables, cranberries and barberries, as well as nuts, bran and almonds.

Calcium is equally necessary at any age. Its salts are part of the blood, as well as interstitial and cellular fluid. It is believed that they are necessary to strengthen protective systems body, as well as for the implementation and maintenance of neuromuscular excitability.

The role of calcium salts in their importance for blood clotting, and their lack quickly affects the activity of the heart muscle. This mineral is especially necessary for the bones of the skeleton.

Calcium is present in many foods. But at the same time, it is quite difficult to be absorbed by the body. It is best to consume it with dairy products, for example, half a liter of milk contains its daily rate.

When building a diet, one should take into account the fact that calcium is actively lost by the body during various stressful situations and during illness. This very quickly affects the state of the whole organism. Therefore, if calcium is lost, its intake should be increased.

Phosphorus is essential for stimulating the growth and activity of the body. It affects bone development and is also very important for the brain. A stable intake of this element is necessary for active mental work. But it should be borne in mind that a constant excess of phosphorus can lead to the formation of tumors.

This mineral is found in foods such as fish liver, cheese, yolk, bran, cucumbers, lettuce, radishes, almonds, nuts, lentils.

Magnesium is essential for the hardness of teeth and bones. This element is also present in the muscles, nerves, lungs, brain, giving them density and elasticity. Lack of magnesium in the diet has a very quick effect. nervous tension.

It is magnesium salts that can protect our body from negative impacts various stresses, by supporting the work of cell membranes in nervous system. Contained in tomatoes, spinach, nuts, celery, wine berries, bran.

Iron is the main element for blood oxidation. Without it, the formation of hemoglobin - red balls - is impossible. With a lack of this microelement, anemia, apathy, reduced vitality and pale infirmity are observed. In the body, iron is deposited in the liver.

Found in lettuce, spinach, asparagus, strawberries, pumpkin, onions, and watermelon.

Mineral salts are inorganic elements. It means that human body cannot synthesize them on its own. The task of a person is a competent approach to building his diet.

In this case, the need for a strict balance in the ratio of mineral salts should be taken into account. Their wrong combination or excess can be harmful and have Negative consequences.

For example, an excessive amount of calcium in the diet can lead to the formation of calcium-containing kidney stones. Also, this element must be correctly combined with phosphorus and potassium. With an excess of table salt, edema and problems with the cardiovascular system may appear. This is because salt retains fluid in the body.

The biological role of mineral salts in the body is great. For their balanced intake, it is necessary to competently approach the preparation of the diet. In this case, it will not be superfluous to consult with nutritionists.

The chemical composition of plant and animal cells is very similar, which indicates the unity of their origin. More than 80 found in cells chemical elements, but only 27 of them have a known physiological role.

All elements are divided into three groups:

• macronutrients, the content of which in the cell is up to 10 - 3%. These are oxygen, carbon, hydrogen, nitrogen, phosphorus, sulfur, calcium, sodium and magnesium, which together make up over 99% of the mass of cells;
• trace elements, the content of which ranges from 10 - 3% to 10 - 12%. These are manganese, copper, zinc, cobalt, nickel, iodine, bromine, fluorine; they account for less than 1.0% of the mass of cells;
• multimicroelements, making up less than 10 - 12%. These are gold, silver, uranium, selenium and others - in total less than 0.01% of the cell mass. Physiological role most of these elements have not been established.

All of the above elements are part of the inorganic and organic matter living organisms or are contained in the form of ions.

Inorganic compounds of cells are represented by water and mineral salts.

The most common inorganic compound in the cells of living organisms is water. Its content in different cells ranges from 10% in tooth enamel to 85% in nerve cells and up to 97% in the cells of the developing embryo. The amount of water in cells depends on the nature of metabolic processes: the more intense they are, the higher the water content. On average, the body of multicellular organisms contains about 80% water. Such high content water indicates an important role due to its chemical nature.

The dipole nature of the water molecule allows it to form an aqueous (solvate) shell around proteins, which prevents them from sticking to each other. This bound water, constituting 4 - 5% of its total content. The rest of the water (about 95%) is called free. Free water is a universal solvent for many organic and inorganic compounds. Most chemical reactions take place only in solutions. The penetration of substances into the cell and the removal of dissimilation products from it in most cases is possible only in dissolved form. Water is also directly involved in biochemical reactions occurring in the cell (hydrolysis reactions). The regulation of the thermal regime of cells is also associated with water, since it has good thermal conductivity and heat capacity.

Water is actively involved in the regulation of osmotic pressure in cells. The penetration of solvent molecules through a semipermeable membrane into a solution of a substance is called osmosis, and the pressure with which the solvent (water) penetrates through the membrane is called osmotic pressure. The value of osmotic pressure increases with increasing concentration of the solution. The osmotic pressure of body fluids in humans and most mammals is equal to the pressure of 0.85% sodium chloride solution. Solutions with this osmotic pressure are called isotonic, more concentrated - hypertonic, and less concentrated - hypotonic. The phenomenon of osmosis underlies wall stress plant cells(turgor).

In relation to water, all substances are divided into hydrophilic (water-soluble) - mineral salts, acids, alkalis, monosaccharides, proteins, etc. and hydrophobic (water-insoluble) - fats, polysaccharides, some salts and vitamins, etc. In addition to water, solvents can be fats and alcohols.

Mineral salts in certain concentrations are necessary for the normal functioning of cells. So, nitrogen and sulfur are part of proteins, phosphorus is part of DNA, RNA and ATP, magnesium is part of many enzymes and chlorophyll, iron is part of hemoglobin, zinc is part of the pancreatic hormone, iodine is part of thyroid hormones etc. Insoluble salts of calcium and phosphorus provide strength to bone tissue, sodium, potassium and calcium cations - irritability of cells. Calcium ions take part in blood coagulation.

Anions of weak acids and weak alkalis bind hydrogen (H+) and hydroxyl (OH-) ions, as a result of which a slightly alkaline reaction is maintained at a constant level in cells and interstitial fluid. This phenomenon is called buffering.

Organic compounds make up about 20 - 30% of the mass of living cells. These include biological polymers - proteins, nucleic acids and polysaccharides, as well as fats, hormones, pigments, ATP, etc.

Squirrels

Proteins make up 10 - 18% of the total cell mass (50 - 80% of the dry mass). The molecular weight of proteins ranges from tens of thousands to many millions of units. Proteins are biopolymers whose monomers are amino acids. All proteins of living organisms are built from 20 amino acids. Despite this, the diversity of protein molecules is enormous. They differ in size, structure and functions, which are determined by the number and order of amino acids. Apart from simple proteins(albumins, globulins, histones) there are also complex ones, which are compounds of proteins with carbohydrates (glycoproteins), fats (lipoproteins) and nucleic acids (nucleoproteins).

Each amino acid consists of a hydrocarbon radical linked to an acidic carboxyl group (-COOH) and a basic amino group (-NH2). Amino acids differ from each other only by radicals. Amino acids are amphoteric compounds that have properties of both acids and bases. This phenomenon makes it possible for acids to form long chains. In this case, strong covalent (peptide) bonds are established between the acidic carbon and the nitrogen of the main groups (-CO-NH-) with the release of a water molecule. Compounds consisting of two amino acid residues are called dipeptides, three - tripeptides, many - polypeptides.

The proteins of living organisms consist of hundreds and thousands of amino acids, that is, they are macromolecules. Various properties and the functions of protein molecules are determined by the sequence of amino acids that are encoded in DNA. This sequence is called the primary structure of the protein molecule, which, in turn, determines the subsequent levels of spatial organization and biological properties proteins. The primary structure of a protein molecule is due to peptide bonds.

The secondary structure of a protein molecule is achieved by its spiralization due to the establishment of hydrogen bonds between the atoms of adjacent turns of the helix. They are weaker than covalent, but, repeated many times, create a fairly strong connection. Functioning in the form of a twisted spiral is characteristic of some fibrillar proteins (collagen, fibrinogen, myosin, actin, etc.).

Many protein molecules become functionally active only after acquiring a globular (tertiary) structure. It is formed by repeatedly folding the spiral into a three-dimensional formation - a globule. This structure is crosslinked, as a rule, by even weaker disulfide bonds. Most proteins (albumins, globulins, etc.) have a globular structure.

Some functions require the participation of proteins with more high level organization, in which there is an association of several globular protein molecules into a single system - a quaternary structure (chemical bonds may be different). For example, a hemoglobin molecule consists of four different globules and a heme group containing an iron ion.

The loss of a protein molecule structural organization called denaturation. It can be caused by various chemical (acids, alkalis, alcohol, salts of heavy metals, etc.) and physical (high temperature and pressure, ionizing radiation, etc.) factors. First, a very weak - Quaternary, then tertiary, secondary, and under more severe conditions, the primary structure is destroyed. If under the influence of the denaturing factor the primary structure is not affected, then when the protein molecules return to normal conditions environment, their structure is completely restored, i.e., renaturation occurs. This property of protein molecules is widely used in medicine for the preparation of vaccines and sera and in Food Industry for food concentrates. With irreversible denaturation (destruction of the primary structure), proteins lose their properties.

Proteins perform the following functions: building, catalytic, transport, motor, protective, signaling, regulatory and energy.

How construction material proteins are part of all cell membranes, hyaloplasm, organelles, nuclear juice, chromosomes and nucleoli.

The catalytic (enzymatic) function is performed by enzyme proteins, which accelerate the course of biochemical reactions in cells by tens and hundreds of thousands of times. normal pressure and a temperature of about 37 °C. Each enzyme can catalyze only one reaction, i.e., the action of enzymes is strictly specific. The specificity of enzymes is due to the presence of one or more active centers in which there is close contact between the molecules of the enzyme and a specific substance (substrate). Some enzymes are used in medical practice and food industry.

The transport function of proteins is to transport substances, such as oxygen (hemoglobin) and some biologically active substances(hormones).

The motor function of proteins is that all types of motor reactions of cells and organisms are provided by special contractile proteins - actin and myosin. They are found in all muscles, cilia and flagella. Their threads are able to contract using the energy of ATP.

The protective function of proteins is associated with the production of special protein substances by leukocytes - antibodies in response to the penetration of foreign proteins or microorganisms into the body. Antibodies bind, neutralize and destroy compounds that are not characteristic of the body. An example of the protective function of proteins is the conversion of fibrinogen into fibrin during blood clotting.

The signal (receptor) function is carried out by proteins due to the ability of their molecules to change their structure under the influence of many chemical and physical factors, as a result of which the cell or organism perceives these changes.

The regulatory function is carried out by hormones of a protein nature (for example, insulin).

The energy function of proteins lies in their ability to be a source of energy in the cell (as a rule, in the absence of others). With complete enzymatic cleavage of 1 g of protein, 17.6 kJ of energy is released.

Carbohydrates

Carbohydrates are an essential component of both animal and plant cells. In plant cells, their content reaches 90% of dry weight (in potato tubers), and in animals - 5% (in liver cells). The composition of carbohydrate molecules includes carbon, hydrogen and oxygen, and the number of hydrogen atoms in most cases is twice the number of oxygen atoms.

All carbohydrates are divided into mono-, di- and polysaccharides. Monosaccharides often contain five (pentoses) or six (hexoses) carbon atoms, the same amount of oxygen and twice as much hydrogen (for example, C6H12OH - glucose). Pentoses (ribose and deoxyribose) are part of nucleic acids and ATP. Hexoses (glucose and fructose) are constantly present in the cells of plant fruits, giving them a sweet taste. Glucose is found in the blood and serves as a source of energy for animal cells and tissues. Disaccharides combine two monosaccharides in one molecule. Dietary sugar (sucrose) consists of glucose and fructose molecules, milk sugar (lactose) includes glucose and galactose. All mono- and disaccharides are highly soluble in water and have a sweet taste. Polysaccharide molecules are formed as a result of the polymerization of monosaccharides. The monomer of polysaccharides - starch, glycogen, cellulose (fiber) is glucose. Polysaccharides are practically insoluble in water and do not have a sweet taste. The main polysaccharides - starch (in plant cells) and glycogen (in animal cells) are deposited in the form of inclusions and serve as reserve energy substances.

Carbohydrates are formed in green plants during photosynthesis and can be used later for the biosynthesis of amino acids, fatty acids and other compounds.

Carbohydrates perform three main functions: building (structural), energy and storage. Cellulose forms the walls of plant cells; complex polysaccharide - chitin - the outer skeleton of arthropods. Carbohydrates in combination with proteins (glycoproteins) are part of bones, cartilage, tendons and ligaments. Carbohydrates act as the main source of energy in the cell: when 1 g of carbohydrates are oxidized, 17.6 kJ of energy is released. Glycogen is stored in the muscles and liver cells as a reserve nutrient.

Lipids

Lipids (fats) and lipoids are essential components of all cells. Fats are esters of high molecular weight fatty acids and the trihydric alcohol glycerol, and lipoids are esters of fatty acids with other alcohols. These compounds are insoluble in water (hydrophobic). Lipids can form complex complexes with proteins (lipoproteins), carbohydrates (glycolipids), residues phosphoric acid(phospholipids), etc. The fat content in the cell ranges from 5 to 15% of the dry matter mass, and in the cells of the subcutaneous adipose tissue - up to 90%.

Fats perform building, energy, storage and protective functions. The bimolecular layer of lipids (mainly phospholipids) forms the basis of all biological cell membranes. Lipids are part of the sheaths of nerve fibers. Fats are a source of energy: with the complete breakdown of 1 g of fat, 38.9 kJ of energy is released. They serve as a source of water released during their oxidation. Fats are a reserve source of energy, accumulating in the adipose tissue of animals and in the fruits and seeds of plants. They protect organs from mechanical damage(for example, the kidneys are wrapped in a soft fatty "case"). Accumulating in the subcutaneous fatty tissue of some animals (whales, seals), fats perform a heat-insulating function.

Nucleic acids Nucleic acids are the primary biological significance and are complex high-molecular biopolymers, the monomers of which are nucleotides. They were first discovered in the nuclei of cells, hence their name.

There are two types of nucleic acids: deoxyribonucleic (DNA) and ribonucleic (RNA). DNA enters mainly into the chromatin of the nucleus, although a small amount of it is also contained in some organelles (mitochondria, plastids). RNA is found in the nucleoli, ribosomes, and in the cytoplasm of the cell.

The structure of the DNA molecule was first deciphered by J. Watson and F. Crick in 1953. It consists of two polynucleotide chains connected to each other. DNA monomers are nucleotides, which include: a five-carbon sugar - deoxyribose, a phosphoric acid residue and a nitrogenous base. Nucleotides differ from one another only in their nitrogenous bases. The composition of DNA nucleotides includes the following nitrogenous bases: adenine, guanine, cytosine and thymine. Nucleotides are connected in a chain by the formation of covalent bonds between the deoxyribose of one and the phosphoric acid residue of the adjacent nucleotide. Both chains are combined into one molecule by hydrogen bonds that arise between the nitrogenous bases of different chains, and due to a certain spatial configuration, two bonds are established between adenine and thymine, and three between guanine and cytosine. As a result, the nucleotides of the two chains form pairs: A-T, G-C. The strict correspondence of nucleotides to each other in paired DNA chains is called complementary. This property underlies the replication (self-doubling) of the DNA molecule, i.e., the formation of a new molecule based on the original one.

replication

Replication happens in the following way. Under the action of a special enzyme (DNA polymerase), hydrogen bonds between the nucleotides of two chains are broken, and the corresponding DNA nucleotides (A-T, G-C) are attached to the released bonds according to the principle of complementarity. Consequently, the order of nucleotides in the "old" DNA strand determines the order of nucleotides in the "new", i.e., the "old" DNA strand is a template for the synthesis of the "new". Such reactions are called matrix synthesis reactions, they are characteristic only for living things. DNA molecules can contain from 200 to 2 x 108 nucleotides. A huge variety of DNA molecules is achieved by their different sizes and different nucleotide sequences.

The role of DNA in a cell is to store, reproduce and transmit genetic information. Thanks to matrix synthesis, the hereditary information of daughter cells exactly matches the mother's.

RNA

RNA, like DNA, is a polymer built from monomers - nucleotides. The structure of RNA nucleotides is similar to that of DNA, but there are the following differences: instead of deoxyribose, RNA nucleotides contain a five-carbon sugar - ribose, and instead of the nitrogenous base of thymine - uracil. The other three nitrogenous bases are the same: adenine, guanine, and cytosine. Compared to DNA, RNA contains fewer nucleotides and, therefore, its molecular weight is smaller.

Double- and single-stranded RNAs are known. Double-stranded RNA is contained in some viruses, performing (like DNA) the role of the keeper and transmitter of hereditary information. In the cells of other organisms, single-stranded RNAs are found, which are copies of the corresponding sections of DNA.

There are three types of RNA in cells: messenger, transport, and ribosomal.

Messenger RNA (i-RNA) consists of 300-30,000 nucleotides and makes up approximately 5% of all RNA contained in the cell. It is a copy of a specific piece of DNA (gene). i-RNA molecules act as carriers of genetic information from DNA to the site of protein synthesis (into ribosomes) and are directly involved in the assembly of its molecules.

Transfer RNA (t-RNA) makes up to 10% of all cell RNA and consists of 75-85 nucleotides. tRNA molecules transport amino acids from the cytoplasm to the ribosomes.

The main part of the cytoplasmic RNA (about 85%) is ribosomal RNA (r-RNA). It is part of the ribosome. rRNA molecules include 3 - 5 thousand nucleotides. It is believed that r-RNA provides a certain spatial relationship between i-RNA and t-RNA.

Mineral salts are mandatory components food, and their absence leads to the death of the body. Mineral substances are actively involved in the life of the body, in the normalization of the functions of its most important systems. Their role in hematopoiesis (iron, copper, cobalt, manganese, nickel) is known, as well as their participation in the formation and regeneration of body tissues, especially bone, where phosphorus and calcium are the main structural elements. Minerals play an important role in the development and growth of teeth. Fluorine, for example, makes dental tissue especially strong.

One of essential functions minerals is to maintain the necessary acid-base balance in the body. Entering into the composition of protein fractions, mineral substances impart to them the properties of living protoplasm. Mineral salts are involved in the function of endocrine and enzyme systems, their role in the normalization of water metabolism is invaluable.

The daily requirement for some minerals in adults is as follows:

• Calcium - 800-100 mg
• Iron - 2 mg
• Phosphorus -1600-2000 mg
• Mel - 2 mg
• Magnesium - 500-600 mg
• Iodine - 100-150 mg
• Potassium - 2-3 mg
• Sodium -4-6 mg
• Zinc -12-16 mg
• Chlorine - 4-6 mg
• Manganese - 4 mg
• Sulfur - 1 mg
• Aluminum - 12-13 mg
• Fluorine -0.8-1.6 mg

Some food products have the ability to selectively concentrate in their composition a significant amount of sometimes rare minerals. Yes, known large quantities silicon in cereals, iodine - in sea ​​plants, copper and zinc - in oysters, cadmium - in scallops, etc.

Acid-base balance. The human body maintains the acid-base balance necessary for its normal functioning. It is distinguished by constancy, however, the nature of nutrition and the predominance of acidic or alkaline compounds in it can affect shifts. acid-base balance. In human nutrition, the predominance of acidic substances is most often noted, as a result of which this balance can shift towards acidity, which is undesirable.

There is evidence that acid shifts in the body contribute to the development of a.

Sources of acidic minerals are foods such as meat, fish, eggs, bread, cereals, bakery products and others containing significant amounts of sulfur, phosphorus and chlorine. Foods rich in calcium, magnesium and potassium (or sodium)! are sources of alkaline substances. These include milk and dairy products (except cheeses), potatoes, vegetables and fruits, berries. It would seem that vegetables, fruits and berries, due to their sour taste should be sources of acidic substances. In fact, as a result of transformations in the body, they serve as suppliers of alkaline substances. Organic acids of vegetables, fruits and berries contain a large number of alkaline and alkaline earth salts, which are retained in the body.

It is desirable to strengthen the diet of people of mature age with products from alkaline environment. This can be achieved by increasing the proportion of milk and dairy products, potatoes, vegetables and fruits in the diet. To the main minerals that it needs; organism, include calcium, potassium, magnesium, phosphorus and iron.

Calcium. The importance of calcium in baby food. One might think that for adults the role of calcium is small, and more than that it is harmful in old age due to the danger of its deposition in the vessels.

However, adults also need calcium; there is evidence that in old age the need for calcium even increases. Calcium salts are constant integral part blood, cell and tissue juices; they strengthen the body's defense mechanisms and play an important role in maintaining normal neuromuscular excitability. Calcium salts are involved in the processes of blood clotting, calcium affects the function of the heart muscle. Of particular importance is calcium in the formation, growth and development of the bones of the skeleton.

Calcium is widely present in many foods, however, it is difficult to digest. The best sources of digestible calcium are milk and dairy products. 0.5 l of milk or 100 g of cheese is guaranteed to satisfy daily requirement in calcium. cereal calcium, bread products it is poorly digested due to its unfavorable ratio in these products with phosphorus and magnesium, and also due to the presence of inositol-phosphoric acid in cereals, which forms indigestible compounds with phosphorus. The same indigestible compounds form with calcium and oxalic acid; therefore, calcium in foods rich in oxalic acid (sorrel, spinach, etc.) is practically (not used in the body.

Meat and fish contain little calcium and cannot be considered as any significant source of it. Milk alone is an excellent source of absorbable calcium, but it can increase the calcium absorption of other foods. Therefore, milk should be an indispensable component of any diet.

Between doses reach 7 or more hours. As a result, the stomach is overfilled, its walls are excessively stretched, the mobility and mixing of food are limited in it, and the processing of its juices worsens. Nutrients become less accessible for processing by enzymes. Food stays in the stomach for a long time, and the work of the digestive glands becomes long and intense. Such nutrition ultimately leads to the development of dysfunction of the gastric glands and indigestion. Elderly people often have impaired functional abilities digestive system, and such an excessive load leads to even more pronounced violations.

The regularity of food intake is extremely important,

i.e. eating always at the same time. At the same time, it produces conditioned reflex to highlight the most active at the set time gastric juice rich in enzymes. Incoming food meets in the stomach prepared soil for vigorous, active digestion. Quite a different thing happens with disordered eating. In these cases, there is no conditioned reflex, there is no preliminary release of juice, and the introduced food enters the stomach, which is not prepared for the processes of digestion.

If the time of eating is not observed for a long time, then digestion processes are inevitably disturbed, often leading to the development of stomach diseases.

It can be said without exaggeration that one of common causes ov and peptic ulcer stomach and duodenum is precisely non-compliance with the diet, disorderly eating with long breaks between these methods.

Eating too much before bed is very harmful. The fact is that the digestive organs need rest, and such a period of rest is night sleep. long continuous work glands of the digestive apparatus leads to a decrease in the digestive power of gastric juice and disruption of its normal separation.

The digestive glands should have 6-10 hours of rest daily. late dinners deprive the secretory apparatus of rest, which leads to overstrain and exhaustion of the digestive glands.

Dinner should be no later than 3 hours before bedtime. Immediately before bedtime, lactic acid foods or fruits (a glass of curdled milk, an apple) are recommended.

Distribution of the daily diet for individual meals is differentiated, depending on the nature labor activity and daily routine.

Mineral salts, like vitamins, must be in our food, as they are necessary for the life and activity of our body.

The main groups of minerals.

1. Sodium. One of the main alkaline elements in the body. Thanks to him, lime and magnesium are retained in blood solutions and tissues. Lack of sodium causes hardening of the walls of the arteries, stagnation of blood in the capillary vessels, gallstones, urinary, hepatic, jaundice. Then sodium removes carbon dioxide from the tissues to the lungs, with a lack of sodium, heart diseases appear, and ic and obese suffocate. Then sodium is the source of hydrochloric acid which is part of the gastric juice. Only thanks to sodium, iron can capture oxygen from the air.

2. Iron. It is the most necessary element for the oxidation of our blood, it contributes to the formation of red balls (hemoglobin) in it. Lack of iron in the body creates acute anemia, reduced vitality, apathy, pale infirmity. The storage place for iron in the body is the liver.

Most iron is found in spinach, lettuce, strawberries, asparagus, onions, pumpkins and watermelons.

3. Potassium. It is an alkali metal necessary for the building of muscles. In the body, it is needed for the liver and spleen, as well as

for the intestines, which helps to digest fats and starches.

Therefore, the food rich in potassium, useful when ah. It is also useful in poor blood circulation, in weakening the activity of the heart, in various inflammations and diseases of the skin, with congestion of blood to the head.

A lack of potassium creates flabbiness and inflexibility of the muscles, lowers mental vitality. Most of all it is found in raw vegetables, in sour fruits, especially lemons, cranberries and barberries, and also in bran, nuts, almonds and chestnuts.

And, since calcium is necessary for the work of the heart muscles and for blood clotting. It is the main source of blood supply with alkaline salts, which is extremely important, since the blood in normal condition alkaline, and if the alkaline balance is disturbed, then death occurs. All our glands, which secrete hormones for blood, cells and tissues, must always have enough calcium, otherwise the body ages prematurely. Children and adolescents require 3-4 times more calcium than adults for the formation of bones, teeth, tissues.

4. Calcium. During illness, especially high temperature, as well as overwork and big trouble a lot of calcium is thrown out of the body. This is immediately reflected in the work of the whole organism: super-acidity of the blood appears, the liver weakens, losing its activity necessary for the destruction of substances that enter it from the blood. toxic substances, tonsils begin to inflame, stones appear in gallbladder, staggering and crumbling teeth, the body is covered with a rash (mainly the hands).

The introduction of one pure calcium into the body does not bring great benefit, it must be introduced along the way in the form of food containing alkali in an organic compound, it is necessary to give egg yolks, yellow turnips, rutabaga, beans, olives, lentils, almonds, wine berries, cauliflower, bran, whey.

5. Phosphorus. Bone development can be delayed due to a lack of phosphorus, despite the sufficiency of calcium, since phosphorus is a stimulus for growth and activity in the body. Phosphorus is still needed for brain work, as it is part of the brain substance; therefore, brain fatigue with increased brain work is associated with a decrease in phosphorus. On the other hand, its disproportionate amount in the body causes various tumors.

Phosphorus is especially rich in fish liver, also egg yolk, cheese, bread bran, radishes, cucumbers, lettuce, nuts, almonds, lentils and dried peas.

6. Sulfur. It is found in all cells and tissues of the human body.

Organism: in the component of hair,

nails, muscles, bile, gases, urine. Is an antiseptic

intestines, moderates excessive oxidation of phosphorus, preserves the strength of the nerves. Lack of sulfur leads to irritable activity, tumors, painful phenomena on the skin. There is a lot of sulfur in horseradish, turnips, cabbage, egg white, bran, walnuts and Chinese nuts, in ripe rye and wheat.

7. Silicon. It goes to the construction of muscles, nerves, skin, hair and nails. Its deficiency causes hair loss, brittle nails, and contributes to diabetes. Most silicon is found in the skin fresh fruit and in cereal bran. In addition, a little in cucumbers, asparagus, head lettuce, parsley, beets and strawberries.

Most chlorine in oysters, whey, egg white, fresh green vegetables - cabbage, celery, parsley. Also found in butter, bananas, eggs, milk and rye bread whole flour.

9. Fluorine. It is found in humans in the spinal bones and teeth and less in the muscles, brain and blood. It is part of the enamel of the teeth: without

fluorine enamel cracks, teeth rot. The bones of the skeleton without fluoride also get sick. Fluoride is found in all cereal grains, nuts, beans, peas, egg whites, fruits and green vegetables. By the way, fluorine is necessary substance in the protoplasm of plants, therefore, in soil devoid of fluorine, plants do not bloom.

10. Iodine. In organisms, it is thyroid gland and is a metabolic regulator. Lack of iodine leads to the formation of a and weakens the immune system, i.e., the body's resistance to all kinds of diseases, reduces physical forces organism.

Most iodine is found in sea ​​kale(algae). Then it is found in turnips, rutabaga, beets, lettuce, tomatoes, also in sea ahs, chilims, oysters, crabs, herrings and lobsters.

11. Salt(cooking). It is very necessary for tissues and blood, as well as for the formation of hydrochloric acid, which is part of the gastric juice. Lack of salt in the body leads to weight loss, and its excess is harmful to the heart.

12. Magnesium. It gives the bones and teeth a special hardness and rigidity. In nerves, muscles, lungs, brains, it is also present in small quantities, giving them elasticity and density. Lack of it is reflected in nervous tension.

Magnesium is found in spinach, tomatoes, celery, nuts, figs, and bran.