What is metabolism in biology: definition. Metabolism (metabolism) and energy conversion in the body What is metabolism in biology briefly

A prerequisite for the existence of any living organism is the constant intake and excretion of final decay products.

What is metabolism in biology

Metabolism, or metabolism, is a special set of chemical reactions that occur in any living organism to maintain its activity and life. Such reactions give the body the opportunity to develop, grow and reproduce, while maintaining its structure and responding to environmental stimuli.

Metabolism is usually divided into two stages: catabolism and anabolism. At the first stage, all complex substances are broken down and become simpler. In the second, along with energy expenditure, nucleic acids, lipids and proteins are synthesized.

The most important role in the metabolic process is played by enzymes that are active. They are able to reduce the activation energy of a physical reaction and regulate metabolic pathways.

Metabolic chains and components are absolutely identical for many species, which is proof of the unity of origin of all living beings. This similarity shows the relatively early appearance of evolution in the history of the development of organisms.

Classification by type of metabolism

What metabolism is in biology is described in detail in this article. All living organisms existing on planet Earth can be divided into eight groups, guided by the source of carbon, energy and oxidizable substrate.

Living organisms can use the energy of chemical reactions or light as a food source. The oxidizable substrate can be either organic or the source of carbon is carbon dioxide or organic matter.

There are microorganisms that, being in different living conditions, use different types of metabolism. It depends on humidity, lighting and other factors.

They can be characterized by the fact that the same organism can have cells with different types of metabolic processes.

Catabolism

Biology considers metabolism and energy through such a concept as “catabolism”. This term is used to describe the process during which large particles of fats, amino acids and carbohydrates are broken down. During catabolism, simple molecules appear that participate in biosynthetic reactions. It is thanks to these processes that the body is able to mobilize energy, converting it into an accessible form.

In organisms that live thanks to photosynthesis (cyanobacteria and plants), the electron transfer reaction does not release energy, but accumulates it thanks to sunlight.

In animals, catabolic reactions are associated with the breakdown of complex elements into simpler ones. Such substances are nitrates and oxygen.

Catabolism in animals is divided into three stages:

Breaking down complex substances into simpler ones.
Breaking down simple molecules into even simpler ones.
Release of energy.

Anabolism

Metabolism (8th grade biology examines this concept) is also characterized by anabolism - a set of metabolic processes of biosynthesis with energy consumption. Complex molecules, which are the energy basis of cellular structures, are successively formed from the simplest precursors.

First, amino acids, nucleotides and monosaccharides are synthesized. The above elements then become active forms thanks to the energy of ATP. And at the last stage, all active monomers are combined into complex structures such as proteins, lipids and polysaccharides.

It is worth noting that not all living organisms synthesize active molecules. Biology (metabolism is described in detail in this article) distinguishes organisms such as autotrophs, chemotrophs and heterotrophs. They get energy from alternative sources.

Energy obtained from sunlight

What is metabolism in biology? The process through which all life on Earth exists and distinguishes living organisms from inanimate matter.

Some protozoa, plants and cyanobacteria feed on the energy of sunlight. In these representatives, metabolism occurs due to photosynthesis - the process of absorbing oxygen and releasing carbon dioxide.

Digestion

Molecules such as starch, proteins and cellulose are broken down before they are used by cells. The digestion process involves special enzymes that break down proteins into amino acids and polysaccharides into monosaccharides.

Animals can secrete such enzymes only from special cells. But microorganisms release such substances into the surrounding space. All substances that are produced thanks to extracellular enzymes enter the body using “active transport”.

Control and regulation

What is metabolism in biology, you can read in this article. Each organism is characterized by homeostasis - the constancy of the internal environment of the body. The presence of such a condition is very important for any organism. Since they are all surrounded by an environment that is constantly changing, in order to maintain optimal conditions inside cells, all metabolic reactions must be correctly and accurately regulated. A good metabolism allows living organisms to constantly contact the environment and respond to its changes.

Historical information

What is metabolism in biology? The definition is at the beginning of the article. The concept of “metabolism” was first used by Theodor Schwann in the forties of the nineteenth century.

Scientists have been studying metabolism for several centuries, and it all began with attempts to study animal organisms. But the term “metabolism” was first used by Ibn al-Nafis, who believed that the whole body is constantly in a state of nutrition and decay, therefore it is characterized by constant changes.

The biology lesson “Metabolism” will reveal the essence of this concept and describe examples that will help increase the depth of knowledge.

The first controlled experiment to study metabolism was obtained by Santorio Santorio in 1614. He described his condition before and after eating, working, drinking water and sleeping. He was the first to notice that most of the food consumed was lost during the process of "imperceptible evaporation."

In initial studies, metabolic reactions were not detected, and scientists believed that living tissue was controlled by a living force.

In the twentieth century, Eduard Buchner introduced the concept of enzymes. From then on, the study of metabolism began with the study of cells. During this period, biochemistry became a science.

What is metabolism in biology? The definition can be given as follows - this is a special set of biochemical reactions that support the existence of an organism.

Minerals

Inorganic substances play a very important role in metabolism. All organic compounds consist of large amounts of phosphorus, oxygen, carbon and nitrogen.

Most inorganic compounds allow you to control the level of pressure inside cells. Also, their concentration has a positive effect on the functioning of muscle and nerve cells.

(iron and zinc) regulate the activity of transport proteins and enzymes. All inorganic microelements are absorbed thanks to transport proteins and are never in a free state.

Metabolism (metabolism) is a set of chemical reactions involved in maintaining the vital activity of cells and organisms.

There are two types of metabolism:

Catabolism is a set of processes that, as a result of fermentation of complex organic substances, lead to the production of simpler substances (fatty acids, amino acids, monosaccharides).
Anabolism is the creation by the body of new substances, tissues and cells from simpler substances obtained as a result of catabolism (cellular proteins, membrane phospholipids, polysaccharides).

As a result of catabolism, not only new, simpler substances are formed, but also energy, which is then used for anabolism. When the balance between these two processes is disrupted, the organism dies.

Classification

Depending on the type of metabolism, all organisms are divided into the following groups:

If organic compounds are the source of carbon for the body, we are talking about heterotrophs.
If the source of carbon for the body is inorganic compounds, these are autotrophs.
If plants or bacteria obtain energy from sunlight through the process of photosynthesis, they are phototrophs.
If, during the process of photosynthesis, plants or bacteria obtain energy from primary molecules, then these are chemotrophs.
Bacteria that obtain energy from organic compounds are called organotrophs.
Bacteria that obtain energy from inorganic compounds are called lithotrophs.

Proper nutrition implies the consumption of all substances necessary for the body: carbohydrates, hydrogen, oxygen, nitrogen, phosphorus, sulfur and about 20 other inorganic elements. If the body does not receive enough nutrients, a malfunction occurs in the body, in which first individual cells, and then entire organs, begin to function incorrectly.

Basic nutrients obtained from food

Carbohydrates are involved in the construction of cellular structures, create a supply of nutrients in the body, participate in the formation of immunity and perform an energy function. A person gets carbohydrates from starch, sugar and fiber.
Proteins are the main building material of tissues. Proteins are necessary for the body because they contain amino acids obtained as a result of the breakdown of proteins. Proteins are found in eggs, milk, fruits, vegetables, soy and grains.
Fats - help form cellular structures, form a vital protective cushion and insulation around internal organs, help absorb fat-soluble vitamins and provide reserve energy.
Minerals and vitamins are part of the body's metabolic pathways. Vitamins are important organic compounds that the human body cannot synthesize on its own and, therefore, must be ensured that they are supplied in sufficient quantities through food.

We can briefly outline what metabolism is in three stages:

The breakdown of complex substances into simpler ones under the influence of enzymes in the digestive system and their absorption into the blood.
Transporting received nutrients to cells and tissues.
Getting rid of metabolic by-products through sweat, urine, feces, exhaled air, etc.

Metabolism

Metabolism is the main vital property of the body; with the cessation of metabolism, death occurs. Metabolism includes two interrelated processes: the absorption of substances entering the body - assimilation and their breakdown - dissimilation. During the process of assimilation, complex organic substances are formed, which are used to build body cells and intercellular structures, and during dissimilation, complex organic substances disintegrate, turning into simpler ones. The process of dissimilation is accompanied by the release of a significant amount of energy necessary for the life of the body. The final products of decomposition that are not involved in further transformations are removed from the body. The main feature of the dissimilation process

is that during the oxygen decay process, most of the energy (about 55%) is stored in the form of ATP and 55%) is stored in the form of ATP and substances (mainly in the new synthesis of organic substances).

Metabolism involves proteins, fats, carbohydrates, water, mineral salts and vitamins. All metabolic processes are interconnected. The intensity of metabolism depends on the age of the person, the nature of the work performed, climatic and other factors. Metabolism is regulated by the nervous system and humoral factors. During diseases, various changes in metabolism occur, sometimes they are the main signs of the disease. For example, with gout, the level of uric acid in the blood is increased and it is deposited in joints, tendons and cartilage. Changes in metabolism can be observed when the activity of the endocrine glands is disrupted, insufficient intake of vitamins into the body, or when certain parts of the nervous system, such as the hypothalamus, are damaged.

Proteins that enter the body with food, under the influence of enzymes in the digestive tract, are broken down into amino acids, which are absorbed into the blood and distributed throughout the body. In the cells of organs and tissues, proteins characteristic of humans are synthesized from them. The unused part of the proteins undergoes breakdown and is removed from the body, and the released energy is used in other reactions (energy function of proteins). Proteins are necessary not only for the construction of cellular structures (construction function), but are an integral part of enzymes, hormones and some other substances. Proteins are part of enzymes as catalysts for many reactions (catalytic function) and antibodies (protective function).

The end products of protein breakdown in the body are water, carbon dioxide and nitrogen-containing substances (ammonia, uric acid, etc.). Protein breakdown products are removed from the body through the excretory organs. Proteins in the body are not stored (or almost not stored). In a healthy adult body, the amount of nitrogen taken in is equal to the amount removed, i.e. Protein is broken down as much as it is supplied (nitrogen equilibrium). In a growing child's body, protein synthesis exceeds their breakdown (positive nitrogen balance). In severe illnesses and during fasting, and often in very elderly people, a negative nitrogen balance can be observed: the amount of nitrogen excreted exceeds the amount introduced. Proteins contain on average 16% nitrogen, i.e. the weight of proteins is 6.25 times the weight of the nitrogen present in them (calculated per 100 g of protein). The resulting amount of nitrogen is multiplied by 6.25 to obtain the amount of protein in grams. The daily protein requirement is on average 100-118 g; it depends on age, the nature of the profession and other conditions. A long-term lack of proteins causes severe disturbances in the body: delayed growth and development in children, changes in the enzymatic systems of the body, in the endocrine glands, etc. A positive nitrogen balance in an adult can occur with the growth of neoplasms - the growth of cells that are not characteristic of the body. If this process is detected in time, timely treatment is possible.

Complex carbohydrates that enter the body with food are broken down in the digestive tract into monosaccharides, which enter the blood and then into the liver, where glycogen is synthesized from glucose. As needed, it turns back into glucose, which is carried throughout the body by blood. The blood glucose level is maintained at the same level (about 0.1%). The liver regulates blood sugar: it contains about 300 g of carbohydrates in the form of glycogen. When a significant amount of sugar or glucose (150-200 g) is taken from food, the blood sugar level increases (food hyperglycemia). Excess sugar is excreted in the urine, i.e. Glucose appears in the urine - glucosuria occurs. When the intrasecretory activity of the pancreas is disrupted, a disease called sugar disease, or diabetes mellitus, occurs. In diabetes mellitus, the blood sugar level rises and increased excretion of sugar in the urine begins (up to 500 g of sugar can be excreted in the urine during the day). Glycogen is not only deposited in the liver, it can accumulate in the muscles. If necessary, glucose enters the blood from both liver glycogen and muscle glycogen. Glucose is not only a structural component of the cytoplasm of cells, but also a necessary component of their growth (energy source); it is very important for the functioning of the nervous system (glycogen is also deposited in nerve cells). If the blood sugar concentration drops to 0.04%, then convulsions, delirium, loss of consciousness, etc. begin. - the activity of the central nervous system is disrupted. It is enough for such a patient to eat regular sugar or introduce glucose into the blood, and all the disorders disappear. A sharp and prolonged decrease in blood sugar - hypoglycemia can lead to more severe disturbances in the body's functioning and lead to death. If there is insufficient intake of carbohydrates from food, they can be formed from proteins and fats.

Carbohydrates break down easily and are the main source of energy in the body, especially during physical activity. A person's daily need for carbohydrates averages 450-500 g. The center for regulating blood sugar is located in the medulla oblongata and diencephalon (subthalamic region) of the brain. The higher centers are located in the cerebral cortex. Adrenaline, a hormone of the adrenal medulla, promotes the conversion of glycogen into glucose and enhances oxidative processes in cells. Its action is opposite to insulin, which promotes the penetration of glucose into cells and the synthesis of glycogen. Other hormones also take part in the regulation of carbohydrate metabolism: hormones of the adrenal cortex, the anterior lobe of the pituitary gland and the thyroid gland.

Fats, like carbohydrates, are used by the body as a source of energy. During the oxidation of fat, more than two times more energy is released than during the oxidation of the same amount of carbohydrates and proteins: during the oxidation of 1 g of fat, 9.3 kcal of heat is released, 1 g of carbohydrates - 4.1 kcal, 1 g of protein - 4.1 kcal

Glycerol formed during the breakdown of fats is easily absorbed, and fatty acids are absorbed only after saponification. In the human body, glycerol and fatty acids form fat, which is unique to the human body. Fat is part of the cells, and amounts of fat not required by the body are stored in the form of fat drops. Fat is deposited mainly in the subcutaneous tissue, omentum, around the kidneys, and is found in the liver and muscles. In humans, fat makes up 10-20% of weight, and in obesity - up to 50%. With obesity, metabolic processes are disrupted. Fat is synthesized not only from consumed fat, but also from proteins and carbohydrates. During fasting, carbohydrates are formed from fats, which are used as a source of energy. In the regulation of fat metabolism, the central nervous system plays an important role, as well as many endocrine glands (genital, pituitary, thyroid, adrenal glands).

The hormonal regulation of protein metabolism is even less studied than the hormonal regulation of lipid metabolism. Since growth consists of the deposition of new protein in the cytoplasm, pituitary growth hormone plays some role in this regulation, but the mechanism of its action is little known. Insulin, sex hormones and cortisol secreted by the adrenal cortex also participate in the regulation of protein metabolism. A very important role in preserving the life of the body is played by the exchange of lipoids, or fat-like substances that make up the nervous tissue and participate in its activity. In their structure, lipoids are close to some hormones and, apparently, are the basis for the formation of sex hormones, adrenal hormone and vitamin D.

Water and mineral salts are not sources of energy or nutrients, but their role is extremely important. Water makes up up to 65% of the body's weight, and in children - up to 80%. Without food, but with the presence of water (its consumption), a person can survive for 40-50 days, and without water he dies after a few days. Water and mineral salts create the internal environment of the body, being the main part of plasma, lymph and tissue fluid. Mineral salts dissolved in water maintain a constant osmotic pressure necessary for the normal functioning of body cells. Water is formed in small quantities in the body during the oxidation of nutrients, especially a lot of it is obtained during the oxidation of fats (118 g of water during the oxidation of 100 g of fat). Water enters the body when drinking and with food, is excreted mainly by the kidneys (1.5 l), partially with exhaled air (500 ml) and by evaporation from the surface of the skin (500 ml). The daily water requirement of an adult is 2-2.5 liters; it may vary depending on climatic conditions and working conditions. In hot weather, water is consumed in large quantities, as well as when working in hot workshops. Water is a solvent for many substances; all physical and chemical reactions of the body take place in it; it plays an important role in the transport of substances. The ratio of the amount of water consumed to the amount excreted is called water balance; It is important that the supply of water covers the consumption, otherwise, as a result of the loss of water, serious disruptions to the vital functions of the body occur.

About 15 chemical elements are introduced into the body with food, some of which are supplied in negligible quantities. A person needs up to 10 g of table salt, 1 g of potassium, 0.3 g of magnesium, 1.5 g of phosphorus, 0.8 g of calcium, 0.012 g of iron, 0.001 mg of copper, 0.0003 g of manganese and 0.00003 g of Yoda. Salts are distributed unevenly in different cells and tissues of the body. Thus, many sodium salts are contained in plasma and intercellular fluid; there are more potassium salts in cells than in body fluids; bones contain a lot of calcium and phosphorus; hemoglobin - copper and iron, and thyroid cells - iodine. Since minerals are constantly removed from the body, they must be replenished in equal quantities with food intake. Lack of salts in the diet can lead to death faster than complete starvation. The need for table salt is due to the fact that its solution plays a major role in maintaining osmotic pressure. Calcium salts are necessary to maintain the activity of the heart: in their absence, the activity of the heart slows down and soon stops completely. The ratio of potassium and calcium salts is also important for the normal functioning of the heart muscle. Sodium, potassium, calcium and chlorine ions play a role in the processes of excitation and inhibition, muscle contraction. Salts, which are necessary in minimal quantities (microelements), are also important for the normal functioning of the body (for example, cobalt is part of vitamin B12; zinc is part of the enzyme carbonic anhydrase, which binds carbon dioxide in the blood; fluorine prevents tooth decay, etc.) .

A balanced diet should fully cover a person’s need for energy and plastic substances. The daily diet of a person who does not engage in physical labor should include about 100 g of protein, 90 g of fat and 400 g of carbohydrates (about 3,000 kcal); mineral salts, vitamins and water are needed. During physical activity, the need for energy and plastic substances increases; therefore, the diet should increase the content of not only fats and carbohydrates, but also proteins.

It is recommended to consume about 50% of proteins and fats in the form of animal products and, when increasing the calorie content of food, to maintain the ratio of proteins, fats and carbohydrates - 1: 1: 4. In this ratio, products are better absorbed. One-sided nutrition (predominance of either protein or carbohydrate foods) is inappropriate, as it disrupts the processes of digestion and metabolism. To reduce body weight, you should reduce your carbohydrate intake.

Daily energy requirement for individuals

(in kilocalories)

People of mental work

People employed in

mechanized production

Manual workers

(partial or absent

mechanization)

Persons performing heavy

muscle work

Metabolism is accompanied by energy exchange - both processes are interconnected. The energy released during dissimilation is consumed in the form of mechanical (in muscles), electrical (nervous and other tissues), chemical (synthesis of new substances) and other types of energy. It is important that all these types of energy are converted into heat, which is released into the environment. The intensity of metabolism can be determined by the amount of heat generated in the body. On average, the human body absorbs about 90% of incoming nutrients. Energy consumption in the body can be counted. With direct calorimetry, the amount of heat released is determined in special chambers; with indirect calorimetry, using special instruments, the volume of inhaled oxygen and exhaled carbon dioxide (gas exchange) is determined and the respiratory coefficient is calculated (the ratio of the volume of exhaled carbon dioxide to the volume of absorbed oxygen - CO2/O2), using which can be used to calculate energy consumption using special tables.

Basic metabolism is the amount of energy spent by the body only to maintain life, i.e. on processes that occur during complete rest (heart function, contraction of respiratory muscles, urine formation, secretion of hormones, etc.). The amount of basal metabolic rate varies depending on a person’s gender, weight, age and other factors. It ranges from 1,000 to 2,000 large calories per day in adult men and from 1,000 to 1,700 in women (an average of 24 large calories per kilogram of weight). During physical activity, in addition to the main metabolism, additional energy consumption occurs (working metabolism of the body). The total energy expenditure, therefore, consists of the basal and working metabolism and during high physical activity can reach 5,000 or more calories. There is a direct relationship between metabolism and heat generation: an increase in metabolism is accompanied by an increase in heat generation and, conversely, with a decrease in metabolism, heat generation also decreases. Heat transfer occurs through the skin through the evaporation of sweat, with exhaled air, with urine and feces. The regulation of heat transfer is based largely on changes in the volume of blood flowing through the vessels of the skin and on the intensity of sweating. When skin vessels dilate and blood flow increases, heat transfer increases, and when blood vessels narrow and blood flow decreases, it decreases. The process of heat transfer and heat generation is regulated by the nervous system - the “thermal center” is located in the intermediate section of the brain.

In the body of a healthy person, there is a balance between the formation of heat and its release: as much heat is released into the environment as it is generated, due to which the body temperature is maintained at the same level. The average body temperature when measured in the armpit is 36.5-36.9 oC. The lowest temperature is observed from 4 to 6 o'clock, the highest - from 16 to 18 o'clock. When the disease occurs, an increase in body temperature is observed due to a violation of thermoregulation; its increase above 41 oC is threatening for the body, since vital processes occurring at certain temperature limits are disrupted. At high temperatures, metabolism increases sharply: the breakdown of one’s own proteins increases (negative nitrogen balance), heart function and breathing become more frequent, blood pressure rises, etc. During intense muscular work, an increase in temperature can lead to heatstroke, especially in conditions of high air temperature. With prolonged cooling, body temperature may decrease compared to normal, i.e. hypothermia may develop. In hot climates or in hot workshops, the main means of cooling the body is sweating. A person can lose up to 9-15 liters of water per day through sweat and give up 5,000-9,000 kcal of heat (1 ml of water takes 0.58 kcal). When the temperature of the external environment changes, the work of the endocrine glands reflexively changes: the thyroid gland, adrenal glands and pancreas (their hormones enhance oxidative processes). The pituitary gland inhibits the secretion of thyroid hormone, reduces metabolism and lowers body temperature.

A prerequisite for the existence of any living organism is the constant supply of nutrients and the removal of final decay products.

Contents [Show]

What is metabolism in biology

The most important role in the metabolic process is played by enzymes, which are active biological catalysts. They are able to reduce the activation energy of a physical reaction and regulate metabolic pathways.

Classification by type of metabolism

Living organisms can use the energy of chemical reactions or light as a food source. The oxidizable substrate can be either organic or inorganic substances. The source of carbon is carbon dioxide or organic matter.

There are microorganisms that, being in different living conditions, use different types of metabolism. It depends on humidity, lighting and other factors.

Multicellular organisms can be characterized by the fact that the same organism can have cells with different types of metabolic processes.

Catabolism

Biology considers metabolism and energy through such a concept as “catabolism”. This term refers to metabolic processes during which large particles of fats, amino acids and carbohydrates are broken down. During catabolism, simple molecules appear that participate in biosynthetic reactions. It is thanks to these processes that the body is able to mobilize energy, converting it into an accessible form.

In organisms that live thanks to photosynthesis (cyanobacteria and plants), the electron transfer reaction does not release energy, but accumulates it thanks to sunlight.

In animals, catabolic reactions are associated with the breakdown of complex elements into simpler ones. Such substances are nitrates and oxygen.

Catabolism in animals is divided into three stages:

Breaking down complex substances into simpler ones.
Breaking down simple molecules into even simpler ones.
Release of energy.

Anabolism

Energy obtained from sunlight

What is metabolism in biology? The process through which all life on Earth exists and distinguishes living organisms from inanimate matter.

Digestion

Control and regulation

Historical information

What is metabolism in biology? The definition is at the beginning of the article. The concept of “metabolism” was first used by Theodor Schwann in the forties of the nineteenth century.

The biology lesson “Metabolism” will reveal the essence of this concept and describe examples that will help increase the depth of knowledge.

In initial studies, metabolic reactions were not detected, and scientists believed that living tissue was controlled by a living force.

In the twentieth century, Eduard Buchner introduced the concept of enzymes. From then on, the study of metabolism began with the study of cells. During this period, biochemistry became a science.

What is metabolism in biology? The definition can be given as follows - this is a special set of biochemical reactions that support the existence of an organism.

Minerals

Inorganic substances play a very important role in metabolism. All organic compounds consist of large amounts of phosphorus, oxygen, carbon and nitrogen.

Most inorganic compounds allow you to control the level of pressure inside cells. Also, their concentration has a positive effect on the functioning of muscle and nerve cells.

Transition metals (iron and zinc) regulate the activity of transport proteins and enzymes. All inorganic microelements are absorbed thanks to transport proteins and are never in a free state.

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Many people have heard about metabolism and its effect on weight. But what does this concept mean and is there a connection between good metabolism and the amount of fat in the body? In order to understand this, it is necessary to understand the very essence of metabolism.

The essence of metabolism

The complex word metabolism has a synonym - metabolism, and this concept is probably heard by more people. In biology, metabolism is a set of chemical reactions that occur in the body of all living beings on the planet, including humans. As a result of these transformations, the work of the whole organism is carried out.

Metabolism - what is it in simple terms? Various substances enter the human body through breathing, food, and drink:

nutritional elements (proteins, fats, carbohydrates);
oxygen;
water;
mineral salts;
vitamins.

All these elements cannot be absorbed by the body in their original form, so the body launches special processes to decompose substances into components and assemble new particles from them. New cells are formed from new components. This is how muscle volume increases, skin regeneration in case of lesions (cuts, ulcers, etc.), tissue renewal, which occurs constantly.

Without metabolism, human life is impossible. It is a mistaken belief that the metabolic process in the body occurs only when we do something. Even in a state of complete rest (which, by the way, is very difficult for the body to provide, because we are always making movements: we blink, turn our heads, move our hands), the body needs to break down complex elements and create simple ones from them in order to renew tissues, ensure the functioning of internal organs, breathing, etc.

The exchange cycle can be divided into 2 processes.

1. Destruction (anabolism) is the breakdown of all elements entering the body into simpler substances.

As you know, protein found in food consists of amino acids. To build new cells, you do not need pure protein, but a set of amino acids that the body receives during the breakdown of protein. Each protein product is made up of different amino acids, so chicken protein cannot be a substitute for milk protein. However, our body, in the process of anabolism, breaks down each of these products, taking from them exactly those valuable “building blocks” that are needed.

During anabolism, energy is released from each substance, which is necessary for the construction of complex molecules. This energy is the very calories, counting which is so important when losing weight.

2. Creation (catabolism) is the synthesis of complex components from simple ones and the construction of new cells from them. You can observe the process of catabolism during the growth of hair and nails or when wounds heal. This also includes the renewal of blood, tissues of internal organs and many processes that take place in the body unnoticed by us.

To create new cells, energy (calories) is needed, which is released during anabolism. If there is too much of this energy, it is not completely spent on the synthesis of molecules, but is stored “in reserve” in fatty tissue.

Protein metabolism

Proteins are of plant and animal origin. Both of these groups of substances are necessary for the normal functioning of the body. Protein compounds are not stored in the body as fat. All protein that enters the body of an adult is broken down and synthesized into new protein at a rate of 1:1. But in children, the process of catabolism (cell creation) prevails over decay - due to the growth of their body.

Protein can be complete or incomplete. The first consists of all 20 amino acids and is found only in animal products. If a protein compound lacks at least 1 amino acid, it is classified as the second type.

Carbohydrate metabolism

Carbohydrates are the main source of energy for our body. They can be complex or simple. The first group is cereals, cereals, bread, vegetables, fruits. These are so-called healthy carbohydrates, which are slowly broken down in the body and provide it with a long-lasting boost of energy. Fast or simple carbohydrates are sugar, white flour products, various sweets, baked goods, carbonated drinks. By and large, our body does not need such food at all: the body will function correctly without it.

Once in the body, complex carbohydrates are converted into glucose. Its level in the blood is relatively the same throughout the entire time. Fast carbohydrates cause this level to fluctuate greatly, which affects both the general well-being of a person and his mood.

When there is an excess, carbohydrates begin to be deposited in the form of fat cells; when there is a shortage, they are synthesized from internal protein and adipose tissue.

Fat metabolism

One of the products of fat processing in the body is glycerin. It is this that, with the participation of fatty acids, is converted into the fat that is deposited in adipose tissue. With an excess supply of lipids, fatty tissue grows and we see the result - the human body becomes loose and increases in volume.

Another place for excess fat to be deposited is the space between the internal organs. Such reserves are called visceral, and they are even more dangerous for humans. Obesity of internal organs does not allow them to work as usual. Most often, people experience fatty liver, because it is the liver that takes the hit first, filtering through itself the products of fat breakdown. Even a thin person can have visceral fat due to lipid metabolism disorders.

The average daily requirement of lipids for a person is 100 g, although this value can be reduced to 20 g taking into account the person’s age, weight, his goal (for example, losing weight), and diseases.

Exchange of water and mineral salts

Water is one of the most important components for humans. It is known that the human body is 70% liquid. Water is present in blood, lymph, plasma, intercellular fluid, and the cells themselves. Without water, most chemical reactions cannot take place.

Many people today are hydrated without realizing it. Every day our body releases water through sweat, urine, and breathing. To replenish reserves, you need to drink up to 3 liters of fluid per day. This standard also includes moisture contained in food products.

Symptoms of water deficiency may include headaches, fatigue, irritability, and lethargy.

Mineral salts make up about 4.5% of the total body weight. They are needed for many metabolic processes, including maintaining bone tissue, transporting impulses in muscles and nerve cells, and creating thyroid hormones. Proper nutrition daily completely replenishes reserves of mineral salts. However, if your diet is not balanced, then various problems may arise due to a lack of salts.

The role of vitamins in the body

When vitamins enter the body, they are not broken down, but become ready-made “building blocks” for building cells. It is for this reason that our body reacts sharply to a lack of one or another vitamin: after all, without its participation, some functions are disrupted.

The norm of vitamins every day for a person is small. However, with modern eating habits, many people experience vitamin deficiency - an acute vitamin deficiency. An excess of these substances leads to hypovitaminosis, which is no less dangerous.

Few people think that the vitamin composition of foods can change greatly when food is processed or stored for a long time. Thus, the amount of vitamins in vegetables and fruits decreases sharply due to long-term storage. Heat treatment can often “kill” all the beneficial properties of food.

Metabolic level

There is such a thing as basal or basic metabolism. This is an indicator of the energy that our body needs to maintain all its functions. The metabolic rate shows how many calories the human body will burn at complete rest. Complete rest means the absence of any physical activity: that is, if you lie on the bed for a day without even batting your eyelashes.

This indicator is very important, because without knowing the level of their metabolism, many women, in an effort to lose weight, reduce the calorie intake to a level that is below the basal metabolism. But basic metabolism is necessary for the functioning of the heart, lungs, blood circulation, etc.

You can independently calculate your metabolic rate on one of the websites on the Internet. To do this, you will need to enter information about your gender, age, height and weight. To find out how many calories you need per day to maintain your weight, you need to multiply your basal metabolic rate by your activity factor. Such calculations can also be made directly on the website.

A faster metabolism allows people to eat more without gaining fat. And this is not to mention the general well-being of a person who, with a fast metabolism, feels healthy, cheerful and happy. What does metabolic rate depend on?

Floor. The male body consumes more energy to maintain its functions than the female body. On average, a man needs 5-6% more calories than a woman. This is due to the fact that the female body naturally has more adipose tissue, which requires less energy expenditure to maintain.
Age. From the age of 25, the human body undergoes changes. Metabolic processes begin to rearrange and slow down. From the age of 30, each subsequent ten years, metabolism slows down by 7-10%. Due to the fact that the rate of metabolic processes decreases, it is easier for an elderly person to gain excess weight. With age, the caloric content of food consumed should decrease by 100 calories per 10 years. And physical activity, on the contrary, should increase. Only in this case will you be able to maintain your figure in the desired shape.
The ratio of fat and muscle tissue in the body. Muscles consume energy even at rest. To maintain their tone, the body has to devote more energy than maintaining fat reserves. An athlete spends 10-15% more calories than an overweight person. This is not about physical activity, of which the athlete certainly has more. And about basic metabolism, that is, the amount of energy that is spent at rest.
Nutrition. Overeating, fasting, eating disorders, large amounts of fatty, unhealthy, heavy food - all this negatively affects the speed of metabolic processes.

Metabolic disorder

The causes of metabolic disorders can be diseases of the thyroid gland, adrenal glands, pituitary gland, and gonads. A factor that we cannot influence - hereditary - can also give impetus to changes in the functioning of the body.

However, the most common cause of slow metabolism is poor eating behavior. This includes overeating, abuse of animal fats, heavy meals, and large gaps between meals. Fans of express diets should know that fasting and the predominance of low-calorie foods in the diet are a sure way to disrupt the internal balance.

Often, bad habits such as smoking and drinking alcohol lead to slower processes. Also at risk are people who lead a sedentary lifestyle, constantly lack sleep, are exposed to frequent stress, and do not receive the full amount of vitamins and minerals.

Why is a slow metabolism so dangerous?

Symptoms by which you can judge about failures in metabolic processes:

excess body weight;
swelling;
deterioration of the skin condition, change in its color to a painful gray;
fragility of nails;
fragility and hair loss;
dyspnea.

In addition to external manifestations, there are also internal ones. These are metabolic diseases that are very individual. Disorders of the body due to internal imbalance can be very different, there are really many of them. After all, metabolism is understood as the totality of all processes of the body, of which there are also a large number.

How to speed up your metabolism?

In order to normalize the speed of metabolic processes, it is necessary to eliminate the reasons due to which the imbalance occurred.

People who have little physical activity in their lives need to increase their physical activity. Don’t rush to rush to the gym and torment your body with back-breaking workouts - this is just as harmful as spending the whole day in front of a monitor. Start small. Walk where you used to travel by public transport. Take steps instead of using the elevator. Gradually increase the load. A good way to “stretch” your body is to participate in sports games - football, basketball, tennis, etc.
The rhythm of modern man often forces him to give up adequate sleep. In this case, it is better to sacrifice watching a movie or other way of relaxation and get a good night's sleep. Inadequate sleep leads to many disorders in the body, including it directly affects a person’s desire to eat fast carbohydrates. But sweets are poorly absorbed in the body of a “sleepy” person, being deposited in problem areas.
Start drinking water. Drink a glass of water after sleep, half an hour before meals and an hour after. Drink water in small sips and no more than 200 ml at a time. By starting to drink at least 2 liters of fluid per day, you will provide your body with the necessary amount of moisture for most metabolic processes.
If you have serious metabolic disorders, take a massage course. It doesn't matter which type you choose. Any massage has the effect of lymphatic drainage, stimulates blood flow and, as a result, “accelerates” the metabolism.

Provide your body with enough oxygen and solar heat. Take a walk in the fresh air, especially in sunny weather. Remember that oxygen is one of the most important elements for normal metabolism. You can try breathing exercises that will teach your body to breathe deeply. And the sun's rays will give you valuable vitamin D, which is very difficult to obtain from other sources.
Be positive. According to statistics, people who are happy more often during the day have a higher metabolic rate than eternal pessimists.
Eat right.

Nutrition - diet for metabolism

Poor eating behavior is the most common cause of slow metabolism. If you eat too often or, conversely, only 1-2 times a day, your metabolism risks being disrupted.

It is optimal to eat every 2-3 hours, that is, 5-6 times a day. Of these, there should be 3 full meals - breakfast, lunch, dinner, and 2-3 light snacks.

The day begins with breakfast, and only under this condition can you count on proper metabolism. Breakfast should be hearty and nutritious, consisting of slow carbohydrates that will give us energy for the day, proteins and fats. For dinner, it is better to leave protein foods - lean fish, meat, poultry and vegetables. As a snack, it is ideal to drink natural yogurt, kefir, eat fruit or some cottage cheese. If you feel hungry before bed, you can indulge in low-fat cottage cheese.

If you have a slow metabolism, you can influence its speed by adding foods to your diet to speed up your metabolism:

citrus fruit;
apples;
almond;
natural black coffee;
fresh green tea without sugar or other additives;
low-fat dairy products;
spinach;
beans;
white and cauliflower, broccoli;
lean turkey meat.

Metabolism - weight loss

Not many people know that weight directly depends on the speed of metabolic processes in our body. The number of calories your body burns at rest depends on your metabolic rate. For one person this is 1000 calories, for another - 2000. The second person, even without playing sports, can afford the energy value of the daily diet almost twice as much as the first.

If you are overweight and have a low basal metabolic rate, you will have to eat very little to lose weight. In addition, a body with a slow metabolism will be very reluctant to give up fat mass. It is more correct to accelerate the metabolism of substances to ensure the normal functioning of the entire body.

Boosting Metabolism Hayley Pomeroy

Our body uses energy even at rest. Therefore, American nutritionist Haley Pomeroy suggests accelerating metabolic processes and losing weight only due to them. If you follow Hayley's instructions exactly, she guarantees you will lose 10 kg in a month with virtually no effort. The lost fat will not return unless you continue to violate the principles of proper nutrition in the future.

The complex proposed by the American will save you from mono-diets, during which you are haunted by painful hunger. Hayley has developed a balanced nutrition plan that is not aimed at reducing the nutritional value of the menu, but at improving the flow of all processes in the body.

In order to maintain metabolism at the same level, it is necessary to constantly feed it with food. This does not mean that there should be a lot of food. Haley recommends eating small, frequent meals. This way your body will be constantly busy processing substances and will not have time to slow down. It is optimal to have 3 hearty meals - breakfast, lunch and dinner. And between them place 2-3 snacks.

Despite the fact that the nutritionist almost does not limit you in the choice of ingredients, you will still have to give up some foods that are harmful to metabolism. These are foods containing sugar, wheat dishes, alcoholic drinks, and fatty dairy products.

Hayley Pomeroy's meal plan lasts 4 weeks. Each week is divided into blocks.

1st block - complex carbohydrates. Duration - 2 days. Your diet should be dominated by foods rich in healthy carbohydrates. These are primarily vegetables, whole grains, and cereals. Make sure you have enough fiber in your menu. Fiber will help maintain normal blood glucose levels, which can fluctuate due to large amounts of carbohydrate foods.
2nd block - protein and vegetable. Duration - 2 days. Our body expends the most calories to process and assimilate protein compounds. Eat low-fat foods containing protein: poultry, meat, fish, soy, cottage cheese, eggs. Add vegetable dishes to protein foods.
3rd block - adding healthy fats. You eat a balanced diet, that is, you consume carbohydrates, proteins, and fats. Give preference to natural vegetable oils, avocados, and peanuts.

You can learn more about Hayley Pomeroy's diet in her book, The Metabolism Diet.

Jillian Michaels - speed up your metabolism

As a child, Jillian Michaels was seriously overweight. Having become acquainted with fitness, the girl decided to devote herself forever to a healthy lifestyle. Now she is a successful woman who is not only in great shape, but also teaches others how to help their body.

Among Gillian's several effective techniques is a special program called “Speed Up Your Metabolism.” It is not designed for beginners in sports, but for those who can withstand an intense hour-long fitness program from the first workout.

First of all, the American asks you to pay attention not to your diet. She advises including foods in your diet that will have a positive effect on your metabolism.

Red beans. This product contains special starch, which is not absorbed by the body, but helps cleanse the intestines. Fiber removes toxins, and the vitamin and mineral composition of beans affects the formation of muscles in both men and women.
Onions and garlic are real fighters against bad cholesterol. The antioxidants contained in onions and garlic are excellent for removing toxins from the body.
Raspberries and strawberries. These berries regulate blood glucose levels. Special substances in strawberries and raspberries prevent the absorption of fat and starch.
Broccoli and other cruciferous vegetables. These are low-calorie foods that will keep you feeling full for a long time.
Whole grain breads, muesli. Cereals are certainly high in calories, and many people avoid them when dieting. But only refined grains and flour dishes pose a danger. Gillian recommends eating oats, buckwheat, barley, and wheat.

The workout, aimed at burning fat and increasing metabolism, is a 50-minute program. These are aerobic or cardio exercises. The workout begins with a 5-minute warm-up and ends with a 5-minute cool-down, the purpose of which is to stretch the muscles and calm the body after exercise.

The exercises are quite simple to perform; anyone can repeat them without the help of an instructor. But only those who are constantly involved in sports can withstand the fast pace of the program. In an effort to lose weight, do not harm your body, because starting from scratch to heavy loads is dangerous for your health. Prepare your body gradually, starting with brisk walking, jogging, and short cardio sessions.

vesdoloi.ru

Metabolism(or metabolism, from the Greek μεταβολή - “transformation, change”) (hereinafter referred to as “O.V.”) is the natural order of transformation of substances and energy in living systems underlying life, aimed at their preservation and self-reproduction; the totality of all chemical reactions occurring in the body.

The German philosopher and thinker Friedrich Engels, when defining life, pointed out that its most important property is constant oxygen. with the surrounding external nature, with the cessation of which life also ceases. Thus, metabolism is an essential and indispensable sign of life.

Without exception, all organs and tissues of organisms are in a state of continuous chemical interaction with other organs and tissues, as well as with the external environment surrounding the organism. Using the isotope tracer method, it was found that intensive metabolism occurs in any living cell.

With food, various substances enter the body from the external environment. In the body, these substances undergo changes (metabolize), as a result of which they are partially converted into substances of the body itself. This is the process of assimilation. In close interaction with assimilation, the reverse process occurs - dissimilation. The substances of a living organism do not remain unchanged, but are more or less quickly broken down with the release of energy; they are replaced by newly assimilated compounds, and the decay products that arise during decomposition are removed from the body. Chemical processes occurring in living cells are characterized by a high degree of order: the reactions of decay and synthesis are organized in a certain way in time and space, coordinated with each other and form an integral, finely regulated system that has developed as a result of long evolution. The close relationship between the processes of assimilation and dissimilation is manifested in the fact that the latter is not only a source of energy in organisms, but also a source of initial products for synthetic reactions.

The order of phenomena characteristic of metabolism is based on the consistency of the rates of individual chemical reactions, which depends on the catalytic action of specific proteins - enzymes. Almost any substance, in order to participate in O. century, must interact with the enzyme. At the same time, it will change at high speed in a very specific direction. Each enzymatic reaction is a separate link in the chain of those transformations (metabolic pathways) that together constitute metabolism. The catalytic activity of enzymes varies over a very wide range and is under the control of a complex and subtle system of regulations that provide the body with optimal living conditions under changing environmental conditions. Thus, the natural order of chemical transformations depends on the composition and activity of the enzyme apparatus, which is adjusted depending on the needs of the body.

For knowledge of metabolism, it is essential to study both the order of individual chemical transformations and the immediate causes that determine this order. O.v. took shape at the very origin of life on Earth, therefore it is based on a biochemical plan common to all organisms on our planet. However, in the process of development of living matter, changes and improvement of oxygen. followed different paths among different representatives of the animal and plant world. Therefore, organisms belonging to different systematic groups and standing at different stages of historical development, along with fundamental similarities in the basic order of chemical transformations, have significant and characteristic differences. The evolution of living nature was accompanied by changes in the structures and properties of biopolymers, as well as energy mechanisms, metabolic regulation and coordination systems.

Metabolic scheme

I. Assimilation

The differences in metabolism among representatives of different groups of organisms are especially significant in the initial stages of the assimilation process. It is believed that primary organisms used organic matter that arose abiogenically for nutrition (see origin of life); with the subsequent development of life, some of the living creatures acquired the ability to synthesize organic substances. On this basis, all organisms can be divided into heterotrophs and autotrophs (see autotrophic organisms and heterotrophic organisms). In heterotrophs, to which all animals, fungi, and many types of bacteria belong, O. v. based on nutrition with ready-made organic substances. True, they have the ability to assimilate some, relatively small, amount of CO2, using it for the synthesis of more complex organic substances. However, this process is accomplished by heterotrophs only through the use of energy contained in the chemical bonds of organic food substances. Autotrophs (green plants and some bacteria) do not need ready-made organic substances and carry out their primary synthesis from their constituent elements. Some of the autotrophs (sulfur bacteria, iron bacteria and nitrifying bacteria) use the energy of oxidation of inorganic substances for this purpose (see chemosynthesis). Green plants form organic substances using the energy of sunlight during the process of photosynthesis - the main source of organic matter on Earth.

Biosynthesis of carbohydrates

During the process of photosynthesis, green plants assimilate CO2 and form carbohydrates. Photosynthesis is a chain of sequential redox reactions in which Chlorophyll, a green pigment capable of capturing solar energy, takes part. Due to the energy of light, photochemical decomposition of water occurs, and oxygen is released into the atmosphere, and hydrogen is used to restore CO2. At relatively early stages of photosynthesis, phosphoglyceric acid is formed, which, when subjected to reduction, produces three-carbon sugars - trioses. Two trioses - phosphoglyceraldehyde and phosphodioxyacetone - are condensed under the action of the enzyme aldolase to form hexose - fructose diphosphate, which, in turn, is converted into other hexoses - glucose, mannose, galactose. The condensation of phosphodioxyacetone with a number of other aldehydes leads to the formation of pentoses. Hexoses formed in plants serve as the starting material for the synthesis of complex carbohydrates - sucrose, starch, inulin, cellulose (fiber), etc.

Pentoses give rise to high-molecular pentosans, which are involved in the construction of plant support tissues. In many plants, hexoses can be converted into polyphenols, phenolcarboxylic acids and other aromatic compounds. As a result of polymerization and condensation, tannins, anthocyanins, flavonoids and other complex compounds are formed from these compounds.

Animals and other heterotrophs obtain carbohydrates in finished form from food, mainly in the form of disaccharides and polysaccharides (sucrose, starch). In the digestive tract, carbohydrates are broken down by enzymes into monosaccharides, which are absorbed into the blood and distributed to all tissues of the body. In tissues, animal reserve polysaccharide glycogen is synthesized from monosaccharides. See carbohydrate metabolism.

Lipid biosynthesis

The primary products of photosynthesis, chemosynthesis and carbohydrates formed from them or absorbed from food are the starting material for the synthesis of lipids - fats and other fat-like substances. For example, the accumulation of fats in ripening seeds of oilseeds occurs due to sugars. Some microorganisms (for example, Torulopsis lipofera) when cultivated in glucose solutions form up to 11% fat per dry matter within 5 hours. Glycerol, necessary for the synthesis of fats, is formed by the reduction of phosphoglyceraldehyde. High-molecular fatty acids - palmitic, stearic, oleic and others, which produce fats when interacting with glycerol, are synthesized in the body from acetic acid - a product of photosynthesis or the oxidation of substances formed as a result of the breakdown of carbohydrates. Animals also obtain fats from food. In this case, fats in the digestive tract are broken down by lipases into glycerol and fatty acids and absorbed by the body. See fat metabolism.

Protein biosynthesis

In autotrophic organisms, protein synthesis begins with the absorption of inorganic nitrogen (N) and the synthesis of amino acids. During the process of nitrogen fixation, some microorganisms absorb molecular nitrogen from the air, which is converted into ammonia (NH3). Higher plants and chemosynthetic microorganisms consume nitrogen in the form of ammonium salts and nitrates, and the latter are first subjected to enzymatic reduction to NH3. Under the action of appropriate enzymes, NH3 then combines with keto or hydroxy acids, resulting in the formation of amino acids (for example, pyruvic acid and NH3 produce one of the most important amino acids, alanine). The amino acids thus formed can further undergo transamination and other transformations, giving all the other amino acids that make up proteins.

Heterotrophic organisms are also capable of synthesizing amino acids from ammonia salts and carbohydrates, but animals and humans receive the bulk of amino acids from food proteins. Heterotrophic organisms cannot synthesize a number of amino acids and must obtain them in finished form as part of food proteins.

Amino acids, when combined with each other under the action of appropriate enzymes, form various proteins (see the article proteins, section Protein biosynthesis). All enzymes are proteins. Some structural and contractile proteins also have catalytic activity. Thus, the muscle protein myosin is capable of hydrolyzing adenosine triphosphate (ATP), which supplies the energy necessary for muscle contraction. Simple proteins, interacting with other substances, give rise to complex proteins - proteins: combining with carbohydrates, proteins form glycoproteins, with lipids - lipoproteins, with nucleic acids - nucleoproteins. Lipoproteins are the main structural component of biological membranes; Nucleoproteins are part of the chromatin of cell nuclei and form cellular protein-synthesizing particles - ribosomes. See also nitrogen in the body, protein metabolism.

II. Dissimilation

The source of energy necessary to maintain life, growth, reproduction, mobility, excitability and other manifestations of vital activity are the oxidation processes of part of those breakdown products that are used by cells to synthesize structural components.

The most ancient and therefore most common for all organisms is the process of anaerobic breakdown of organic substances, which occurs without the participation of oxygen (see fermentation, glycolysis). Later, this initial mechanism for obtaining energy by living cells was supplemented by the oxidation of the resulting intermediate products with air oxygen, which appeared in the Earth’s atmosphere as a result of photosynthesis. This is how intracellular or tissue respiration arose. For more details, see biological oxidation.

Carbohydrate dissimilation

The main source of energy stored in chemical bonds in most organisms is carbohydrates. The breakdown of polysaccharides in the body begins with their enzymatic hydrolysis. For example, in plants, during seed germination, the starch stored in them is hydrolyzed by amylases; in animals, starch absorbed from food is hydrolyzed under the action of salivary and pancreatic amylases, forming maltose. Maltose is further hydrolyzed to form glucose. In the animal body, glucose is also formed as a result of the breakdown of glycogen. Glucose undergoes further transformations in the processes of fermentation or glycolysis, which results in the formation of pyruvic acid. The latter, depending on the type of metabolism of a given organism, formed in the process of historical development, can further undergo various transformations. During various types of fermentations and during glycolysis in muscles, pyruvic acid undergoes anaerobic transformations. Under aerobic conditions - during respiration - it can undergo oxidative decarboxylation with the formation of acetic acid, and also serve as a source of formation of other organic acids: oxalic-acetic, citric, cis-aconitic, isocitric, oxalic-succinic, ketoglutaric, succinic, fumaric and malic . Their mutual enzymatic transformations, leading to the complete oxidation of pyruvic acid to CO2 and H2O, are called the tricarboxylic acid cycle, or the Krebs cycle.

Dissimilation of fats also begins with their hydrolytic breakdown by lipases with the formation of free fatty acids and glycerol; these substances can then easily oxidize, ultimately yielding CO2 and H2O. The oxidation of fatty acids occurs mainly through the so-called β-oxidation, i.e., in such a way that two carbon atoms are split off from the fatty acid molecule, giving the remainder of acetic acid, and a new fatty acid is formed, which can undergo further β-oxidation. The resulting acetic acid residues are either used for the synthesis of various compounds (for example, aromatic compounds, isoprenoids, etc.) or are oxidized to CO2 and H2O. See also fat metabolism, lipids.

Dissimilation of proteins begins with their hydrolytic cleavage by proteolytic enzymes, resulting in the formation of low molecular weight peptides and free amino acids. This kind of secondary formation of amino acids occurs, for example, very intensively during seed germination, when proteins contained in the endosperm or in the cotyledons of the seed are hydrolyzed to form free amino acids, partly used to build the tissues of the developing plant, and partly subjected to oxidative decomposition. The oxidative breakdown of amino acids that occurs during the dissimilation process occurs through deamination and leads to the formation of the corresponding keto or hydroxy acids. These latter are either subject to further oxidation to CO2 and H2O, or are used for the synthesis of various compounds, including new amino acids. In humans and animals, a particularly intensive breakdown of amino acids occurs in the liver.

Free MH3 formed during deamination of amino acids is poisonous to the body; it binds to acids or is converted into urea, uric acid, asparagine or glutamine. In animals, ammonium salts, urea and uric acid are excreted from the body, while in plants, asparagine, glutamine and urea are used in the body as reserve sources of nitrogen. Thus, one of the most important biochemical differences between plants and animals is the almost complete absence of nitrogenous waste in the former. The formation of urea during the oxidative dissimilation of amino acids is carried out mainly through the so-called ornithine cycle, which is closely related to other transformations of proteins and amino acids in the body. Dissimilation of amino acids can also occur through their decarboxylation, in which CO2 and some amine or a new amino acid are formed from an amino acid (for example, when histidine is decarboxylated, histamine is formed, a physiologically active substance, and when aspartic acid is decarboxylated, a new amino acid is formed - (α- or β-alanine) Amines can undergo methylation to form various betaines and important compounds such as choline.Plants use amines (along with some amino acids) for the biosynthesis of alkaloids.

III. Relationship between the metabolism of carbohydrates, lipids, proteins and other compounds

All biochemical processes occurring in the body are closely related to each other. The relationship between protein metabolism and redox processes occurs in various ways. Individual biochemical reactions underlying the respiration process occur due to the catalytic action of the corresponding enzymes, i.e. proteins. At the same time, the products of protein breakdown themselves - amino acids - can undergo various redox transformations - decarboxylation, deamination, etc.

Thus, the products of deamination of aspartic and glutamic acids - oxalic-acetic and α-ketoglutaric acids - are at the same time the most important links in the oxidative transformations of carbohydrates that occur during respiration. Pyruvic acid, the most important intermediate product formed during fermentation and respiration, is also closely related to protein metabolism: interacting with NH3 and the corresponding enzyme, it produces the important amino acid α-alanine. The close connection between the processes of fermentation and respiration with lipid metabolism in the body is manifested in the fact that phosphoglyceraldehyde, formed in the first stages of carbohydrate dissimilation, is the starting material for the synthesis of glycerol. On the other hand, as a result of the oxidation of pyruvic acid, acetic acid residues are obtained, from which high-molecular fatty acids and various isoprenoids (terpenes, carotenoids, steroids) are synthesized. Thus, the processes of fermentation and respiration lead to the formation of compounds necessary for the synthesis of fats and other substances.

IV. The role of vitamins and minerals in metabolism

Vitamins, water and various mineral compounds occupy an important place in the transformation of substances in the body. Vitamins participate in numerous enzymatic reactions as part of coenzymes. Thus, a derivative of vitamin B1 - thiamine pyrophosphate - serves as a coenzyme in the oxidative decarboxylation of α-keto acids, including pyruvic acid; the phosphate ester of vitamin B6 - pyridoxal phosphate - is necessary for catalytic transamination, decarboxylation and other amino acid metabolism reactions. A derivative of vitamin A is part of the visual pigment. The functions of a number of vitamins (for example, ascorbic acid) have not been fully elucidated. Different types of organisms differ both in their ability to biosynthesize vitamins and in their needs for the set of certain vitamins supplied with food, which are necessary for normal metabolism.

An important role in mineral metabolism is played by Na, K, Ca, P, as well as trace elements and other inorganic substances. Na and K are involved in bioelectrical and osmotic phenomena in cells and tissues, in the mechanisms of permeability of biological membranes; Ca and P are the main components of bones and teeth; Fe is part of the respiratory pigments - hemoglobin and myoglobin, as well as a number of enzymes. For the activity of the latter, other microelements (Cu, Mn, Mo, Zn) are also necessary.

A decisive role in the energy mechanisms of metabolism is played by phosphoric acid esters and, above all, adenosine phosphoric acids, which perceive and accumulate energy released in the body in the processes of glycolysis, oxidation, and photosynthesis. These and some other energy-rich compounds (see high-energy compounds) transfer the energy contained in their chemical bonds for use in the process of mechanical, osmotic and other types of work or for carrying out synthetic reactions that involve energy consumption (see also bioenergetics).

V. Regulation of metabolism

The amazing consistency and coherence of metabolic processes in a living organism is achieved through strict and flexible coordination of metabolic processes. both in cells and in tissues and organs. This coordination determines for a given organism the nature of metabolism that has developed in the process of historical development, supported and directed by the mechanisms of heredity and the interaction of the organism with the external environment.

Regulation of metabolism at the cellular level is carried out by regulating the synthesis and activity of enzymes. The synthesis of each enzyme is determined by the corresponding gene. Various intermediate products of oxygen, acting on a certain section of the DNA molecule, which contains information about the synthesis of a given enzyme, can induce (start, enhance) or, conversely, repress (stop) its synthesis. Thus, E. coli, with an excess of isoleucine in the nutrient medium, stops the synthesis of this amino acid. Excess isoleucine has two effects:

a) inhibits (inhibits) the activity of the enzyme threonine dehydratase, which catalyzes the first stage of the chain of reactions leading to the synthesis of isoleucine, and
b) represses the synthesis of all enzymes necessary for the biosynthesis of isoleucine (including threonine dehydratase).

Inhibition of threonine dehydratase is carried out according to the principle of allosteric regulation of enzyme activity.

The theory of genetic regulation proposed by the French scientists F. Jacob and J. Monod considers repression and induction of enzyme synthesis as two sides of the same process. Various repressors are specialized receptors in the cell, each of which is “tuned” to interact with a specific metabolite that induces or represses the synthesis of a particular enzyme. Thus, in cells, polynucleotide chains of DNA contain “instructions” for the synthesis of a wide variety of enzymes, and the formation of each of them can be caused by the effect of a signal metabolite (inducer) on the corresponding repressor (for more details, see molecular genetics, operon).

The most important role in the regulation of metabolism and energy in cells is played by protein-lipid biological membranes surrounding the protoplasm and the nucleus, mitochondria, plastids and other subcellular structures located in it. The entry and exit of various substances into the cell is regulated by the permeability of biological membranes. A significant portion of enzymes are associated with membranes into which they are, as it were, “built in.” As a result of the interaction of a particular enzyme with lipids and other components of the membrane, the conformation of its molecule, and therefore its properties as a catalyst, will be different than in a homogeneous solution. This circumstance is of great importance for the regulation of enzymatic processes and metabolism in general.

The most important means by which the regulation of metabolism in living organisms is carried out are hormones. For example, in animals, with a significant decrease in the content of caxapa in the blood, the release of adrenaline increases, which promotes the breakdown of glycogen and the formation of glucose. With excess sugar in the blood, insulin secretion increases, which inhibits the breakdown of glycogen in the liver, resulting in less glucose entering the blood. An important role in the mechanism of action of hormones belongs to cyclic adenosine monophosphoric acid (cAMP). In animals and humans, hormonal regulation of metabolism. is closely related to the coordinating activity of the nervous system (see nervous regulation).

Thanks to a set of closely interconnected biochemical reactions that make up metabolism, the interaction of the organism with the environment occurs, which is an indispensable condition for life. Friedrich Engels wrote: “From metabolism through nutrition and excretion... flow all other simple factors of life...” (“Anti-Dühring”, 1966, p. 80). Thus, the development (ontogenesis) and growth of organisms, heredity and variability, irritability and higher nervous activity - these most important manifestations of life can be understood and subordinated to the will of man on the basis of elucidating the hereditarily determined patterns of metabolism and the shifts occurring in it under the influence of changing conditions external environment (within the normal reaction range of a given organism). See also biology, biochemistry, genetics, molecular biology and literature under these articles. (biochemist, Doctor of Biological Sciences, professor (1944), corresponding member of the USSR Academy of Sciences Vaclav Leonovich Kretovich)

VI. Metabolic disorders

Any disease is accompanied by metabolic disorders. They are especially distinct in disorders of the trophic and regulatory functions of the nervous system and the endocrine glands controlled by it. Metabolism is also disturbed by abnormal nutrition (excessive or insufficient and qualitatively inferior food intake, for example, lack or excess of vitamins in food, etc.). Expression of a general violation of O. century. (and thereby energy exchange), caused by changes in the intensity of oxidative processes, are shifts in the main metabolism. An increase in it is typical for diseases associated with increased function of the thyroid gland, a decrease - with insufficiency of this gland, loss of functions of the pituitary gland and adrenal glands and general starvation. There are disorders of protein, fat, carbohydrate, mineral, and water metabolism; however, all types of metabolism are so closely interconnected that such a division is arbitrary.

Metabolic disorders are expressed in insufficient or excessive accumulation of substances involved in metabolism, in changes in their interaction and the nature of transformations, in the accumulation of intermediate metabolic products, in incomplete or excessive excretion of oxygen products. and in the formation of substances that are not characteristic of normal metabolism. Thus, diabetes mellitus is characterized by insufficient absorption of carbohydrates and a violation of their conversion into fat; Obesity causes excessive conversion of carbohydrates into fat; Gout is associated with impaired excretion of uric acid from the body. Excessive excretion of uric acid, phosphoric acid and oxalate salts in the urine can lead to the precipitation of these salts and to the development of kidney stones. Insufficient excretion of a number of end products of protein metabolism due to some kidney diseases leads to uremia.

Accumulation in the blood and tissues of a number of intermediate metabolic products (lactic, pyruvic, acetoacetic acids) is observed in cases of disturbance of oxidative processes, nutritional disorders and vitamin deficiencies; disturbance of mineral metabolism can lead to shifts in acid-base balance. A cholesterol metabolism disorder underlies atherosclerosis and some types of gallstone disease. Serious metabolic disorders include impaired protein absorption due to thyrotoxicosis, chronic suppuration, and some infections; impaired absorption of water in diabetes insipidus, lime and phosphorus salts in rickets, osteomalacia and other diseases of bone tissue, sodium salts in Addison's disease.

Diagnosis of metabolic disorders is based on the study of gas exchange, the relationship between the amount of a particular substance entering the body and its excretion, and the determination of the chemical components of blood, urine and other secretions. To study metabolic disorders, isotope tracers are administered (for example, radioactive iodine - mainly 131I - for thyrotoxicosis).

Treatment of metabolic disorders is aimed mainly at eliminating the causes that cause them. See also "molecular diseases", hereditary diseases and literature under these articles. (S. M. Leites)

Read more about metabolism in the literature:

Engels F., Dialectics of Nature, Marx Karl, Engels F., Works, 2nd edition, volume 20;
Engels F., Anti-Dühring, ibid.;
Wagner P., Mitchell G., Genetics and metabolism translated from English M., 1958;
Christian Boehmer Anfinsen. Molecular foundations of evolution, translation from English, M., 1962;
Jacob Francois, Monod Jacques. Biochemical and genetic mechanisms of regulation in a bacterial cell, in the book: Molecular Biology. Problems and prospects, Moscow, 1964;
Oparin Alexander Ivanovich. The emergence and initial development of life, M., 1966;
Skulachev Vladimir Petrovich. Accumulation of energy in a cell, M., 1969;
Molecules and cells, translation from English, c. 1 - 5, M., 1966 - 1970;
Kretovich Vaclav Leonovich. Fundamentals of plant biochemistry, 5th edition, M., 1971;
Zbarsky Boris Ilyich, Ivanov I. I., Mardashev Sergey Rufovich. Biological chemistry, 5th ed., Leningrad, 1972.

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Metabolism is a process that occurs in the human body every second. This term should be understood as the totality of all reactions of the body. Metabolism is the integrity of absolutely any energy and chemical reactions that are responsible for ensuring normal life activity and self-reproduction. It occurs between the intercellular fluid and the cells themselves.

Life is simply impossible without metabolism. Thanks to metabolism, any living organism adapts to external factors.

It is noteworthy that nature has designed man so competently that his metabolism occurs automatically. This is what allows cells, organs and tissues to recover independently after the influence of certain external factors or internal failures.

Thanks to metabolism, the regeneration process occurs without interference.

In addition, the human body is a complex and highly organized system capable of self-preservation and self-regulation.

What is the essence of metabolism?

It would be true to say that metabolism is the change, transformation, processing of chemicals, as well as energy. This process consists of 2 main interconnected stages:

destruction (catabolism). It involves the breakdown of complex organic substances entering the body into simpler ones. This is a special energy exchange that occurs during the oxidation or breakdown of a certain chemical or organic substance. As a result, energy is released in the body;
rise (anabolism). During this process, important substances for the body are formed - acids, sugar and protein. This plastic exchange occurs with the obligatory expenditure of energy, which gives the body the opportunity to grow new tissues and cells.

Catabolism and anabolism are two equal processes in metabolism. They are extremely closely related to each other, and occur cyclically and sequentially. To put it in simple terms, both processes are extremely important for a person, because they give him the opportunity to maintain an adequate level of vital activity.

If a disturbance in anabolism occurs, then in this case there is a significant need for additional use of anabolic steroids (those substances that can enhance cell renewal).

Several important metabolic stages occur during life:

obtaining the necessary nutrients that enter the body with food;
absorption of vital substances into the lymph and bloodstream, where breakdown into enzymes occurs;
distribution of the resulting substances throughout the body, release of energy and their absorption;
excretion of metabolic products through urination, defecation and sweat.

Causes and consequences of metabolic failures and metabolism

If a failure occurs at any stage of catabolism or anabolism, then this process becomes a prerequisite for disruption of the entire metabolism. Such changes are so pathological that they prevent the human body from functioning normally and carrying out the process of self-regulation.

An imbalance of metabolic processes can occur at any stage of a person’s life. It is especially dangerous in childhood, when all organs and structures are at the stage of formation. In children, disruptions in metabolism are fraught with the following serious diseases:

rickets;
anemia;
hypoglycemia during pregnancy and beyond.

There are main risk factors for such a process:

heredity (mutations at the gene level, hereditary diseases);
the wrong way of a person’s life (bad habits, stress, poor nutrition, sedentary sedentary work, lack of a daily routine);
living in an area that is polluted from an environmental point of view (smoke, dusty air, dirty drinking water).

There may be several reasons for the failure of metabolic processes. These may be pathological changes in the functioning of important glands: adrenal glands, pituitary gland and thyroid.

In addition, the prerequisites for failure include non-compliance with the diet (dry food, frequent overeating, morbid obsession with strict diets), as well as poor heredity.

There are a number of external signs by which you can independently learn to recognize the problems of catabolism and anabolism:

underweight or overweight;
somatic fatigue and swelling of the upper and lower extremities;
weakened nail plates and brittle hair;
skin rashes, pimples, peeling, pallor or redness.

How to establish exchanges using nutrition?

We have already figured out what metabolism is in the body. Now you should understand its features and recovery methods.

The primary metabolism in the body and its first stage. During its course, food and nutrients are supplied. There are quite a lot of foods that can have a beneficial effect on metabolism and metabolism, for example:

foods rich in coarse vegetable fiber (beets, celery, cabbage, carrots);
lean meat (skinless chicken fillet, veal);
green tea, citrus fruits, ginger;
fish rich in phosphorus (especially sea fish);
exotic fruits (avocados, coconuts, bananas);
greens (dill, parsley, basil).

If your metabolism is excellent, then your body will be slim, your hair and nails will be strong, your skin will have no cosmetic defects, and you will always feel good.

In some cases, food products that help improve metabolic processes may not be pleasant enough to taste and may not be appetizing. Despite this, it is difficult to do without them in terms of adjusting metabolism.

Not only thanks to plant-based foods, but also with the right approach to your routine, you can restore your body and metabolism. However, it is important to know that this will not be possible in a short time.

Metabolic restoration is a long and gradual process that does not require deviations from the course.

When dealing with this issue, you should always focus on the following postulates:

compulsory hearty breakfast;
strict diet;
maximum fluid intake.

To maintain your metabolism you need to eat small and frequent meals. It is important to remember that breakfast is the most important meal of the day, which starts the metabolism. It should include high-carbohydrate cereals, but in the evening, on the contrary, it is better to refuse them and give preference to low-calorie protein products, such as kefir and cottage cheese.

Drinking large amounts of mineral or purified water without gas will help speed up your metabolism. We must also not forget about snacks, which should include coarse fiber. It is this that will help draw out the maximum amount of toxins and cholesterol from the body, so much so that drugs that lower cholesterol in the blood will not be needed, metabolism will do everything itself.

Cells constantly carry out metabolism (metabolism) - diverse chemical transformations that ensure their growth, vital activity, constant contact and exchange with the environment. Thanks to metabolism, proteins, fats, carbohydrates and other substances that make up the cell are continuously broken down and synthesized. The reactions that make up these processes occur with the help of special enzymes in a specific cell organelle and are characterized by high organization and orderliness. Thanks to this, relative constancy of composition, formation, destruction and renewal of cellular structures and intercellular substance are achieved in cells.

Metabolism is inextricably linked with the processes of energy conversion. As a result of chemical transformations, the potential energy of chemical bonds is converted into other types of energy used for the synthesis of new compounds, to maintain the structure and function of cells, etc.

Metabolism consists of two interconnected processes occurring simultaneously in the body - plastic and energy metabolism .

Plastic metabolism (anabolism, assimilation) - the totality of all reactions of biological synthesis. These substances are used to build cell organelles and create new cells during division. Plastic exchange is always accompanied by the absorption of energy.

Energy metabolism (catabolism, dissimilation) - a set of reactions that break down complex high-molecular organic substances - proteins, nucleic acids, fats, carbohydrates - into simpler, low-molecular ones. This releases energy contained in the chemical bonds of large organic molecules. The released energy is stored in the form of energy-rich phosphate bonds of ATP.

The reactions of plastic and energy metabolism are interconnected and in their unity constitute the metabolism and transformation of energy in each cell and in the body as a whole.

Plastic exchange

The essence of plastic metabolism is that cell substances are formed from simple substances entering the cell from the outside. Let us consider this process using the example of the formation of the most important organic compounds of the cell - proteins.

Protein synthesis, a complex, multi-step process, involves DNA, mRNA, tRNA, ribosomes, ATP and various enzymes. The initial stage of protein synthesis is the formation of a polypeptide chain from individual amino acids located in

strictly defined sequence. The main role in determining the order of amino acids, i.e. The primary structure of a protein belongs to DNA molecules. The sequence of amino acids in proteins is determined by the sequence of nucleotides in the DNA molecule. A section of DNA characterized by a specific sequence of nucleotides is called a gene. A gene is a section of DNA that is an elementary piece of genetic information. Thus, the synthesis of each specific protein is determined by the gene. Each amino acid in the polypeptide chain corresponds to a combination of three nucleotides - a triplet, or codon. It is three nucleotides that determine the addition of one amino acid to the polypeptide chain. For example, a DNA section with an AAC triplet corresponds to the amino acid leucine, a TTT triplet to lysine, and TGA to threonine. This correlation between nucleotides and amino acids is called the genetic code. Proteins contain 20 amino acids and only 4 nucleotides. Only a code consisting of three consecutive bases could ensure the use of all 20 amino acids in the structures of protein molecules. In total, the genetic code contains 64 different triplets, representing possible combinations of four nitrogenous bases in threes, which is more than enough to encode 20 amino acids. Each triplet codes for one amino acid, but most amino acids are coded for by more than one codon. Currently, the DNA code has been completely deciphered. For each amino acid, the composition of the triplets encoding it has been precisely determined. For example, the amino acid arginine can correspond to DNA nucleotide triplets such as GCA, GCG, GCT, GCC, TCT, TCC.

Protein synthesis is carried out on ribosomes, and information about the structure of the protein is encrypted in DNA located in the nucleus. In order for a protein to be synthesized, information about the amino acid sequence in its primary structure must be delivered to the ribosomes. This process includes two stages: transcription and translation.

Transcription (literally - rewriting) proceeds as a reaction of matrix synthesis. On a DNA chain, as on a template, according to the principle of complementarity, an mRNA chain is synthesized, which in its nucleotide sequence exactly copies (complementary) the polynucleotide chain of DNA, and thymine in DNA corresponds to uracil in RNA. Messenger RNA is not a copy of the entire DNA molecule, but only part of it - one gene that carries information about the structure of the protein that needs to be assembled. There are special mechanisms for “recognizing” the starting point of synthesis, selecting the DNA strand from which information is read, as well as mechanisms for completing the process, in which special codons are involved. This is how messenger RNA is formed. An mRNA molecule carrying the same information as genes is released into the cytoplasm. The movement of RNA through the nuclear envelope into the cytoplasm occurs thanks to special proteins that form a complex with the RNA molecule.

In the cytoplasm, a ribosome is strung onto one end of the mRNA molecule; amino acids in the cytoplasm are activated with the help of enzymes and are added, again with the help of special enzymes, to tRNA (a special binding site for this amino acid). Each amino acid has its own tRNA, one of the sections of which (anticodon) is a triplet of nucleotides corresponding to a specific amino acid and complementary to a strictly defined mRNA triplet.

The next stage of biosynthesis begins - broadcast : assembly of polypeptide chains on an mRNA template. As the protein molecule is assembled, the ribosome moves along the mRNA molecule, and it does not move smoothly, but intermittently, triplet after triplet. As the ribosome moves along the mRNA molecule, amino acids corresponding to the triplets of the mRNA are delivered here using tRNA. To each triplet at which the ribosome stops in its movement along the filamentous mRNA molecule, a tRNA is attached in a strictly complementary manner. In this case, the amino acid bound to the tRNA ends up at the active center of the ribosome. Here, special ribosomal enzymes cleave the amino acid from the tRNA and attach it to the previous amino acid. After the installation of the first amino acid, the ribosome moves one triplet, and the tRNA, leaving the amino acid, migrates into the cytoplasm after the next amino acid. Using this mechanism, the protein chain is built up step by step. Amino acids are combined in it in strict accordance with the location of the coding triplets in the chain of the mRNA molecule. The further the ribosome travels along the mRNA, the larger the segment of the protein molecule is “assembled.” When the ribosome reaches the opposite end of the mRNA, synthesis is complete. The filamentous protein molecule separates from the ribosome. An mRNA molecule can be used repeatedly to synthesize polypeptides, just like a ribosome. One mRNA molecule can contain several ribosomes (polyribosomes). Their number is determined by the length of the mRNA.

Protein biosynthesis is a complex multi-step process, each link of which is catalyzed by certain enzymes and supplied with energy by ATP molecules.

Energy metabolism

The process opposite to synthesis is dissimilation - a set of splitting reactions. As a result of dissimilation, the energy contained in the chemical bonds of food substances is released. This energy is used by the cell to carry out various work, including assimilation. When food substances are broken down, energy is released in stages with the participation of a number of enzymes. Energy metabolism is usually divided into three stages.

The first stage is preparatory . At this stage, complex high-molecular organic compounds are broken down enzymatically, by hydrolysis, into simpler compounds - the monomers from which they are composed: proteins - into amino acids, carbohydrates - into monosaccharides (glucose), nucleic acids - into nucleotides, etc. At this stage, a small amount of energy is released, which is dissipated in the form of heat.

The second stage is oxygen-free, or anaerobic. It is also called anaerobic respiration (glycolysis) or fermentation. Glycolysis occurs in animal cells. It is characterized by steps, the participation of more than a dozen different enzymes and the formation of a large number of intermediate products. For example, in muscles, as a result of anaerobic respiration, a six-carbon glucose molecule breaks down into 2 molecules of pyruvic acid (C3H403), which are then reduced to lactic acid (C3H603). Phosphoric acid and ADP take part in this process. The overall expression of the process is as follows:

C6H1 206+ 2H3P04+ 2ADP -» 2C3H603+ 2ATP + 2H20.

During the fission, about 200 kJ of energy is released. Part of this energy (about 80 kJ) is spent on the synthesis of two ATP molecules, due to which 40% of the energy is stored in the form of a chemical bond in the ATP molecule. The remaining 120 kJ of energy (more than 60%) is dissipated as heat. This process is ineffective.

During alcoholic fermentation, from one molecule of glucose, as a result of a multi-stage process, two molecules of ethyl alcohol and two molecules of CO2 are ultimately formed

C6H1206+ 2H3P04+ 2ADP -> 2C2H5OH ++ 2C02+ 2ATP + 2H20.

In this process, the energy output (ATP) is the same as in glycolysis. The fermentation process is a source of energy for anaerobic organisms.

The third stage is oxygen, or aerobic respiration, or oxygen splitting . At this stage of energy metabolism, the subsequent breakdown of organic substances formed at the previous stage occurs by oxidizing them with atmospheric oxygen to simple inorganic substances, which are the final products - CO2 and H20. Oxygen respiration is accompanied by the release of a large amount of energy (about 2600 kJ) and its accumulation in ATP molecules.

In summary, the equation for aerobic respiration looks like this:

2C3H603+ 602+ 36ADP -» 6C02+ 6H20 + 36ATP + 36H20.

Thus, during the oxidation of two molecules of lactic acid, 36 energy-intensive ATP molecules are formed due to the released energy. Consequently, aerobic respiration plays the main role in providing the cell with energy.