Biology test on the topic "Molecular level" (Grade 9). Energy accumulators in the body Use of ATP as energy accumulators

ATP is the universal energy "currency" of the cell. One of the most amazing "inventions" of nature is the molecules of the so-called "macroergic" substances, in the chemical structure of which there are one or more bonds that act as energy storage devices. Several similar molecules have been found in nature, but only one of them, adenosine triphosphoric acid (ATP), is found in the human body. This is a rather complex organic molecule, to which 3 negatively charged residues of inorganic phosphoric acid PO are attached. It is these phosphorus residues that are connected with the organic part of the molecule by "macroergic" bonds, which are easily destroyed during various intracellular reactions. However, the energy of these bonds is not dissipated in space in the form of heat, but is used for the movement or chemical interaction of other molecules. It is thanks to this property that ATP performs the function of a universal energy storage (accumulator) in the cell, as well as a universal “currency”. After all, almost every chemical transformation that occurs in a cell either absorbs or releases energy. According to the law of conservation of energy, the total amount of energy formed as a result of oxidative reactions and stored in the form of ATP is equal to the amount of energy that the cell can use for its synthetic processes and the performance of any functions. As a "payment" for the opportunity to perform this or that action, the cell is forced to spend its supply of ATP. In this case, it should be emphasized that the ATP molecule is so large that it is not able to pass through the cell membrane. Therefore, ATP produced in one cell cannot be used by another cell. Each cell of the body is forced to synthesize ATP for its needs on its own in the quantities in which it is necessary to perform its functions.

Three sources of ATP resynthesis in the cells of the human body. Apparently, the distant ancestors of the cells of the human body existed many millions of years ago, surrounded by plant cells, which supplied them with carbohydrates in excess, and there was not enough oxygen or not at all. It is carbohydrates that are the most used component of nutrients for the production of energy in the body. And although most of the cells of the human body have acquired the ability to use proteins and fats as energy raw materials, some (for example, nerve, red blood, male sex) cells are able to produce energy only due to the oxidation of carbohydrates.

The processes of primary oxidation of carbohydrates - or rather, glucose, which, in fact, constitutes the main substrate of oxidation in cells - occur directly in the cytoplasm: it is there that enzyme complexes are located, due to which the glucose molecule is partially destroyed, and the released energy is stored in the form of ATP. This process is called glycolysis, it can take place in all cells of the human body without exception. As a result of this reaction, from one 6-carbon molecule of glucose, two 3-carbon molecules of pyruvic acid and two molecules of ATP are formed.

Glycolysis is a very fast, but relatively inefficient process. The pyruvic acid formed in the cell after the completion of the glycolysis reactions almost immediately turns into lactic acid and sometimes (for example, during heavy muscular work) enters the blood in very large quantities, since this is a small molecule that can freely pass through the cell membrane. Such a massive release of acidic metabolic products into the blood disrupts homeostasis, and the body has to turn on special homeostatic mechanisms in order to cope with the consequences of muscle work or other active action.

The pyruvic acid formed as a result of glycolysis still contains a lot of potential chemical energy and can serve as a substrate for further oxidation, but this requires special enzymes and oxygen. This process occurs in many cells that contain special organelles - mitochondria. The inner surface of mitochondrial membranes is composed of large lipid and protein molecules, including a large number of oxidative enzymes. Inside the mitochondria, 3-carbon molecules formed in the cytoplasm penetrate - usually it is acetic acid (acetate). There they are included in a continuously ongoing cycle of reactions, during which carbon and hydrogen atoms are alternately split off from these organic molecules, which, when combined with oxygen, turn into carbon dioxide and water. In these reactions, a large amount of energy is released, which is stored in the form of ATP. Each molecule of pyruvic acid, having gone through a complete cycle of oxidation in mitochondria, allows the cell to obtain 17 ATP molecules. Thus, the complete oxidation of 1 glucose molecule provides the cell with 2+17x2 = 36 ATP molecules. It is equally important that fatty acids and amino acids, i.e., components of fats and proteins, can also be included in the process of mitochondrial oxidation. Thanks to this ability, mitochondria make the cell relatively independent of what foods the body eats: in any case, the necessary amount of energy will be obtained.

Some of the energy is stored in the cell in the form of a molecule of creatine phosphate (CrP), which is smaller and more mobile than ATP. It is this small molecule that can quickly move from one end of the cell to the other - to where energy is most needed at the moment. CrF itself cannot give energy to the processes of synthesis, muscle contraction or conduction of a nerve impulse: this requires ATP. But on the other hand, CRF is easily and practically without loss able to give all the energy contained in it to the adenazine diphosphate (ADP) molecule, which immediately turns into ATP and is ready for further biochemical transformations.

Thus, the energy expended during the functioning of the cell, i.e. ATP can be renewed due to three main processes: anaerobic (oxygen-free) glycolysis, aerobic (with the participation of oxygen) mitochondrial oxidation, and also due to the transfer of the phosphate group from CrF to ADP.

The creatine phosphate source is the most powerful, since the reaction of CrF with ADP is very fast. However, the supply of CrF in the cell is usually small - for example, muscles can work with maximum effort due to CrF for no more than 6-7 s. This is usually enough to start the second most powerful - glycolytic - source of energy. In this case, the resource of nutrients is many times greater, but as work progresses, there is an increasing tension in homeostasis due to the formation of lactic acid, and if such work is performed by large muscles, it cannot last more than 1.5-2 minutes. But during this time, mitochondria are almost completely activated, which are able to burn not only glucose, but also fatty acids, the supply of which in the body is almost inexhaustible. Therefore, an aerobic mitochondrial source can work for a very long time, although its power is relatively low - 2-3 times less than the glycolytic source, and 5 times less than the power of the creatine phosphate source.

Features of the organization of energy production in various tissues of the body. Different tissues have different saturation of mitochondria. They are least in bones and white fat, most of all in brown fat, liver and kidneys. There are quite a lot of mitochondria in nerve cells. Muscles do not have a high concentration of mitochondria, but due to the fact that skeletal muscles are the most massive tissue of the body (about 40% of the body weight of an adult), it is the needs of muscle cells that largely determine the intensity and direction of all energy metabolism processes. I.A. Arshavsky called this "energy rule of skeletal muscles."

With age, two important components of energy metabolism change at once: the ratio of the masses of tissues with different metabolic activity changes, as well as the content of the most important oxidative enzymes in these tissues. As a result, energy metabolism undergoes quite complex changes, but in general, its intensity decreases with age, and quite significantly.

energy exchange

energy exchange is the most integral function of the body. Any syntheses, activity of any organ, any functional activity inevitably affects the energy metabolism, since according to the law of conservation, which has no exceptions, any act associated with the transformation of matter is accompanied by the expenditure of energy.

Energy costs organisms are made up of three unequal parts of basal metabolism, energy supply of functions, as well as energy consumption for growth, development and adaptive processes. The ratio between these parts is determined by the stage of individual development and specific conditions (Table 2).

Basal Metabolism- this is the minimum level of energy production that always exists, regardless of the functional activity of organs and systems, and is never equal to zero. Basal metabolism consists of three main types of energy expenditure: the minimum level of functions, futile cycles and reparative processes.

The minimum energy requirement of the body. The question of the minimum level of functions is quite obvious: even in conditions of complete rest (for example, restful sleep), when no activating factors act on the body, it is necessary to maintain a certain activity of the brain and endocrine glands, liver and gastrointestinal tract, heart and blood vessels , respiratory muscles and lung tissue, tonic and smooth muscles, etc.

Futile cycles. Less well known is that in every cell of the body, millions of cyclic biochemical reactions are continuously taking place, as a result of which nothing is produced, but for their implementation a certain amount of energy is required. These are the so-called futile cycles, processes that preserve the "combat capability" of cellular structures in the absence of a real functional task. Like a spinning top, futile cycles give stability to the cell and all its structures. The energy expenditure to maintain each of the futile cycles is small, but there are many of them, and as a result, this translates into a fairly significant proportion of basal energy expenditure.

reparative processes. Numerous complexly organized molecules involved in metabolic processes sooner or later begin to be damaged, losing their functional properties or even acquiring toxic ones. Continuous "repair and restoration work" is needed, removing damaged molecules from the cell and synthesizing new ones in their place, identical to the previous ones. Such reparative processes occur constantly in every cell, since the lifetime of any protein molecule usually does not exceed 1-2 weeks, and there are hundreds of millions of them in any cell. Environmental factors - unfavorable temperature, increased background radiation, exposure to toxic substances and much more - can significantly shorten the life of complex molecules and, as a result, increase the stress of reparative processes.

The minimum level of functioning of the tissues of a multicellular organism. The functioning of the cell is always some outside work. For a muscle cell, this is its contraction, for a nerve cell, it is the production and conduction of an electrical impulse, for a glandular cell, it is the production of a secret and the act of secretion, for an epithelial cell, it is pinocytosis or another form of interaction with surrounding tissues and biological fluids. Naturally, any work cannot be carried out without the expenditure of energy for its implementation. But any work, in addition, leads to a change in the internal environment of the body, since the waste products of an active cell may not be indifferent to other cells and tissues. Therefore, the second echelon of energy consumption during the performance of a function is associated with the active maintenance of homeostasis, which sometimes consumes a very significant part of the energy. Meanwhile, not only the composition of the internal environment changes in the course of performing functional tasks, the structures often change, and often in the direction of destruction. So, with the contraction of skeletal muscles (even of a small intensity), ruptures of muscle fibers always occur, i.e. the integrity of the form is broken. The body has special mechanisms for maintaining shape constancy (homeomorphosis), which ensure the speedy recovery of damaged or altered structures, but again, this consumes energy. And, finally, it is very important for a developing organism to maintain the main tendencies of its development, regardless of what functions have to be activated as a result of exposure to specific conditions. Maintaining the invariability of the direction and channels of development (homeoresis) is another form of energy consumption during the activation of functions.

For a developing organism, an important item of energy consumption is the actual growth and development. However, for any, including a mature organism, the processes of adaptive rearrangements are no less energy-consuming in terms of volume and very similar in essence. Here, energy expenditures are aimed at activating the genome, destroying obsolete structures (catabolism) and synthesizing (anabolism).

The costs of basal metabolism and the costs of growth and development significantly decrease with age, and the costs of performing functions become qualitatively different. Since it is methodically extremely difficult to separate basal energy expenditure and energy expenditure into growth and development processes, they are usually considered together under the name "BX".

Age dynamics of basal metabolism. Since the time of M. Rubner (1861), it is well known that in mammals, as the body weight increases, the intensity of heat production per unit mass decreases; while the amount of exchange calculated per unit area remains constant (the "surface rule"). These facts still do not have a satisfactory theoretical explanation, and therefore, empirical formulas are used to express the relationship between body size and metabolic rate. For mammals, including humans, the M. Kleiber formula is currently most often used:

M \u003d 67.7 P 0 75 kcal / day,

where M is the heat production of the whole organism, and P is the body weight.

However, age-related changes in basal metabolism cannot always be described using this equation. During the first year of life, heat production does not decrease, as would be required by the Klaiber equation, but remains at the same level or even slightly increases. Only at the age of one is reached approximately the intensity of metabolism (55 kcal / kg day), which is “required” according to the Klaiber equation for an organism weighing 10 kg. Only from the age of 3, the intensity of the basal metabolism begins to gradually decrease, and reaches the level of an adult - 25 kcal / kg day - only by the period of puberty.

Energy cost of growth and development processes. Often, an increased basal metabolic rate in children is associated with growth costs. However, accurate measurements and calculations carried out in recent years have shown that even the most intensive growth processes in the first 3 months of life do not require more than 7-8% of the daily energy intake, and after 12 months they do not exceed 1%. Moreover, the highest level of energy consumption of the child's body was noted at the age of 1 year, when the rate of its growth becomes 10 times lower than at the age of six months. Significantly more "energy-intensive" were those stages of ontogenesis when the growth rate decreases, and significant qualitative changes occur in organs and tissues due to the processes of cellular differentiation. Special studies by biochemists have shown that in tissues that enter the stage of differentiation processes (for example, in the brain), the content of mitochondria increases sharply, and, consequently, oxidative metabolism and heat production increase. The biological meaning of this phenomenon is that in the process of cell differentiation, new structures, new proteins and other large molecules are formed, which the cell was not able to produce before. Like any new business, this requires special energy costs, while growth processes are an established "batch production" of protein and other macromolecules in a cell.

In the process of further individual development, a decrease in the intensity of basal metabolism is observed. It turned out that the contribution of various organs to the basal metabolism changes with age. For example, the brain (which makes a significant contribution to the main metabolism) in newborns is 12% of body weight, and in an adult - only 2%. The internal organs grow just as unevenly, which, like the brain, have a very high level of energy metabolism even at rest - 300 kcal / kg day. At the same time, muscle tissue, the relative amount of which almost doubles during postnatal development, is characterized by a very low metabolic rate at rest - 18 kcal/kg day. In an adult, the brain accounts for approximately 24% of basal metabolism, the liver for 20%, the heart for 10%, and skeletal muscle for 28%. In a one-year-old child, the brain accounts for 53% of the basal metabolism, the liver contributes about 18%, and the skeletal muscles account for only 8%.

Rest exchange in school-age children. It is possible to measure the basal metabolism only in the clinic: this requires special conditions. But the rest exchange can be measured in each person: it is enough for him to be able to fast and be in muscle rest for several tens of minutes. The resting exchange rate is slightly higher than the basal exchange rate, but this difference is not fundamental. The dynamics of age-related changes in resting metabolism is not reduced to a simple decrease in the intensity of metabolism. Periods characterized by a rapid decrease in metabolic intensity are replaced by age intervals in which resting metabolism stabilizes.

At the same time, a close relationship is found between the nature of the change in the intensity of metabolism and the growth rate (see Fig. 8 on p. 57). The bars in the figure show relative annual body weight gains. It turns out that the greater the relative growth rate, the greater the decrease in the resting metabolic rate during this period.

The figure shows another feature - distinct gender differences: girls in the studied age range are about a year ahead of boys in terms of changes in growth rates and metabolic intensity. At the same time, a close relationship is found between the intensity of resting metabolism and the growth rate of children during the half-growth jump - from 4 to 7 years. In the same period, the change of milk teeth to permanent ones begins, which can also serve as one of the indicators of morphofunctional maturation.

In the process of further development, the decrease in the intensity of the basal metabolism continues, and now in close connection with the processes of puberty. In the initial stages of puberty, the metabolic rate in adolescents is about 30% higher than in adults. A sharp decrease in the indicator begins at stage III, when the gonads are activated, and continues until puberty. As is known, the pubertal growth spurt also coincides with the achievement of stage III of puberty, i.e. and in this case, the regularity of the decrease in the intensity of metabolism during the periods of the most intensive growth remains.

Boys in their development during this period lag behind girls by about 1 year. In strict accordance with this fact, the intensity of metabolic processes in boys is always higher than in girls of the same calendar age. These differences are small (5-10%), but stable throughout the entire period of puberty.

thermoregulation

Thermoregulation, i.e. maintaining a constant temperature of the core of the body, is determined by two main processes: heat production and heat transfer. Heat production (thermogenesis) depends primarily on the intensity of metabolic processes, while heat transfer is determined by thermal insulation and a whole complex of rather complex physiological mechanisms, including vasomotor reactions, activity of external respiration and sweating. In this regard, thermogenesis is attributed to the mechanisms of chemical thermoregulation, and methods of changing heat transfer are referred to as mechanisms of physical thermoregulation. With age, both those and other mechanisms change, as well as their importance in maintaining a stable body temperature.

Age development of thermoregulation mechanisms. Purely physical laws lead to the fact that as the mass and absolute dimensions of the body increase, the contribution of chemical thermoregulation decreases. So, in newborns, the value of thermoregulatory heat production is approximately 0.5 kcal/kg h deg, and in an adult - 0.15 kcal/kg h deg.

A newborn child, when the environmental temperature drops, can increase heat production to almost the same values as an adult, up to 4 kcal / kg h. However, due to low thermal insulation (0.15 deg m 2 h / kcal), the range of chemical thermoregulation in a newborn child is very small - no more than 5 °. It should be taken into account that the critical temperature ( Th), at which thermogenesis is activated, is +33 °C for a full-term baby, by the adult state it drops to +27 ... +23 °C. However, in clothes, the thermal insulation of which is usually 2.5 KLO, or 0.45 deg-m 2 h / kcal, the critical temperature value decreases to +20 ° C, so the child in his usual clothes at room temperature is in a thermoneutral environment , i.e. under conditions that do not require additional costs to maintain body temperature.

Only during the procedure of changing clothes to prevent cooling, the child of the first months of life should include sufficiently powerful mechanisms of heat production. Moreover, children of this age have special, specific mechanisms of thermogenesis that are absent in adults. An adult in response to cooling begins to shiver, including the so-called "contractile" thermogenesis, i.e. additional heat production in the skeletal muscles (cold shivering). The design features of the child's body make such a mechanism of heat production ineffective, so the so-called "non-contractile" thermogenesis is activated in children, localized not in the skeletal muscles, but in completely different organs.

These are internal organs (first of all, the liver) and special brown adipose tissue, saturated with mitochondria (that's why its brown color) and having high energy capabilities. The activation of heat production of brown fat in a healthy child can be seen by an increase in skin temperature in those parts of the body where brown fat is located more superficially - the interscapular region and neck. By changing the temperature in these areas, one can judge the state of the mechanisms of thermoregulation of the child, the degree of his hardening. The so-called "hot nape" of a child in the first months of life is associated precisely with the activity of brown fat.

During the first year of life, the activity of chemical thermoregulation decreases. In a child of 5-6 months, the role of physical thermoregulation increases markedly. With age, the bulk of brown fat disappears, but even before the age of 3, the reaction of the largest part of brown fat, the interscapular fat, remains. There are reports that in adults working in the North, in the open air, brown adipose tissue continues to function actively. Under normal conditions, in a child older than 3 years, the activity of non-contractile thermogenesis is limited, and the specific contractile activity of skeletal muscles - muscle tone and muscle tremor - begins to play the leading role in increasing heat production when chemical thermoregulation is activated. If such a child finds himself at normal room temperature (+20 ° C) in shorts and a T-shirt, heat production is activated in him in 80 cases out of 100.

Strengthening of growth processes during the half-growth jump (5-6 years) leads to an increase in the length and surface area of the limbs, which ensures a regulated heat exchange of the body with the environment. This, in turn, leads to the fact that starting from the age of 5.5-6 years (especially clearly in girls) there are significant changes in the thermoregulatory function. The thermal insulation of the body increases, and the activity of chemical thermoregulation is significantly reduced. This method of body temperature regulation is more economical, and it is he who becomes predominant in the course of further age development. This period of development of thermoregulation is sensitive for hardening procedures.

With the onset of puberty, the next stage in the development of thermoregulation begins, which manifests itself in the breakdown of the developing functional system. In 11-12-year-old girls and 13-year-old boys, despite the continuing decrease in the intensity of resting metabolism, the corresponding adjustment of vascular regulation does not occur. Only in adolescence, after the completion of puberty, the possibilities of thermoregulation reach the definitive level of development. Increasing the thermal insulation of the tissues of one's own body makes it possible to do without the inclusion of chemical thermoregulation (i.e., additional heat production) even when the ambient temperature drops by 10-15 ° C. This reaction of the body, of course, is more economical and efficient.

Nutrition

All the substances necessary for the human body, which are used to produce energy and build their own body, come from the environment. As the child grows older, towards the end of the first year of life, more and more switches to independent nutrition, and after 3 years, the child’s nutrition is not much different from the adult’s nutrition.

Structural components of food substances. Human food is of plant and animal origin, but regardless of this, it consists of the same classes of organic compounds - proteins, fats and carbohydrates. Actually, these same classes of compounds make up basically the body of the person himself. At the same time, there are differences between animal and plant foods, and quite important ones.

Carbohydrates. The most massive component of plant foods is carbohydrates (most often in the form of starch), which form the basis of the energy supply of the human body. For an adult, it is required to receive carbohydrates, fats and proteins in a ratio of 4:1:1. Since children's metabolic processes are more intense, and mainly due to the metabolic activity of the brain, which feeds almost exclusively on carbohydrates, children should receive more carbohydrate food - in a ratio of 5:1:1. In the first months of life, the child does not receive plant foods, but there are relatively many carbohydrates in women's milk: it is about the same fat as cow's milk, contains 2 times less protein, but 2 times more carbohydrates. The ratio of carbohydrates, fats and proteins in human milk is approximately 5:2:1. Artificial mixtures for feeding children in the first months of life are prepared on the basis of approximately twice diluted cow's milk with the addition of fructose, glucose and other carbohydrates.

Fats. Plant foods are rarely rich in fats, but the components contained in vegetable fats are essential for the human body. Unlike animal fats, vegetable fats contain many so-called polyunsaturated fatty acids. These are long-chain fatty acids with double bonds in their structure. Such molecules are used by human cells to build cell membranes, in which they play a stabilizing role, protecting cells from the invasion of aggressive molecules and free radicals. Due to this property, vegetable fats have anti-cancer, antioxidant and anti-radical activity. In addition, a large amount of valuable vitamins A and E are usually dissolved in vegetable fats. Another advantage of vegetable fats is the absence of cholesterol in them, which can be deposited in human blood vessels and cause their sclerotic changes. Animal fats, on the contrary, contain a significant amount of cholesterol, but practically do not contain vitamins and polyunsaturated fatty acids. However, animal fats are also essential for the human body, as they are an important component of energy supply, and in addition, they contain lipokinins, which help the body absorb and process its own fat.

Squirrels. Plant and animal proteins also differ significantly in their composition. While all proteins are made up of amino acids, some of these essential building blocks can be synthesized by human cells, while others cannot. There are few of these latter, only 4-5 species, but they cannot be replaced by anything, therefore they are called essential amino acids. Plant foods contain almost no essential amino acids - only legumes and soybeans contain a small amount of them. Meanwhile, in meat, fish and other products of animal origin, these substances are widely represented. The lack of some essential amino acids sharply negatively affects the dynamics of growth processes and the development of many functions, most significantly on the development of the child's brain and intellect. For this reason, children who suffer from long-term malnutrition at an early age often remain mentally handicapped for life. That is why children should in no case be limited in the use of animal food: at least milk and eggs, as well as fish. Apparently, the same circumstance is connected with the fact that children under 7 years old, according to Christian traditions, should not fast, that is, refuse animal food.

Macro- and microelements. Food products contain almost all chemical elements known to science, with the possible exception of radioactive and heavy metals, as well as inert gases. Some elements, such as carbon, hydrogen, nitrogen, oxygen, phosphorus, calcium, potassium, sodium and some others, are part of all food products and enter the body in very large quantities (tens and hundreds of grams per day). Such substances are commonly referred to as macronutrients. Others are found in food in microscopic doses, which is why they are called trace elements. These are iodine, fluorine, copper, cobalt, silver and many other elements. Iron is often referred to as trace elements, although its amount in the body is quite large, since iron plays a key role in the transport of oxygen within the body. The lack of any of the trace elements can cause serious illness. Lack of iodine, for example, leads to the development of severe thyroid disease (so-called goiter). Lack of iron leads to iron deficiency anemia - a form of anemia that adversely affects the performance, growth and development of the child. In all such cases, nutrition correction is necessary, the inclusion in the diet of products containing the missing elements. So, iodine is found in large quantities in seaweed - kelp, in addition, iodized table salt is sold in stores. Iron is found in beef liver, apples and some other fruits, as well as in Hematogen children's toffee sold in pharmacies.

Vitamins, beriberi, metabolic diseases. Vitamins are organic molecules of medium size and complexity that are not normally produced by the cells of the human body. We are forced to get vitamins from food, as they are necessary for the work of many enzymes that regulate biochemical processes in the body. Vitamins are very unstable substances, so cooking on fire almost completely destroys the vitamins contained there. Only raw foods contain vitamins in a noticeable amount, so vegetables and fruits are the main source of vitamins for us. Predatory animals, as well as the indigenous people of the North, who eat almost exclusively meat and fish, get enough vitamins from raw animal products. There are practically no vitamins in fried and boiled meat and fish.

Lack of vitamins is manifested in various metabolic diseases, which are combined under the name of beriberi. About 50 vitamins have now been discovered, and each of them is responsible for its own “site” of metabolic processes, respectively, and there are several dozen diseases caused by beriberi. Scurvy, beriberi, pellagra and other diseases of this kind are widely known.

Vitamins are divided into two large groups: fat-soluble and water-soluble. Water-soluble vitamins are found in large quantities in vegetables and fruits, while fat-soluble vitamins are found more often in seeds and nuts. Olive, sunflower, corn and other vegetable oils are important sources of many fat-soluble vitamins. However, vitamin D (anti-rachitis) is found mainly in fish oil, which is extracted from the liver of cod and some other marine fish.

In the middle and northern latitudes, by spring, in the plant food preserved from autumn, the amount of vitamins decreases sharply, and many people - residents of northern countries - experience beriberi. Salted and sour foods (cabbage, cucumbers and some others), which are high in many vitamins, help to overcome this condition. In addition, vitamins are produced by the intestinal microflora, therefore, with normal digestion, a person is supplied with many of the most important B vitamins in sufficient quantities. In children of the first year of life, the intestinal microflora has not yet been formed, so they should receive a sufficient amount of mother's milk, as well as fruit and vegetable juices, as sources of vitamins.

Daily requirement for energy, proteins, vitamins. The amount of food eaten per day directly depends on the rate of metabolic processes, since food must fully compensate for the energy spent on all functions (Fig. 13). Although the intensity of metabolic processes decreases with age in children older than 1 year, an increase in their body weight leads to an increase in total (gross) energy consumption. Accordingly, the need for essential nutrients also increases. Below are reference tables (Tables 3-6) showing the approximate daily intake of nutrients, vitamins and essential minerals for children. It should be emphasized that the tables give the mass of pure substances without taking into account the water included in any food, as well as organic substances that are not related to proteins, fats and carbohydrates (for example, cellulose, which makes up the bulk of vegetables).

Test. Molecular level. 1 option. Grade 9

A1. Which of the chemical elements is contained in the cells in the greatest amount:
1.nitrogen
2.oxygen
3.coal
4.hydrogen
A2. Name the chemical element that is part of ATP, all protein monomers and nucleic acids.
1)N 2)P 3)S 4)Fe
A3. Indicate a chemical compound that is NOT a carbohydrate.
1) lactose 2) chitin 3) keratin 4) starch
A4. What is the name of the protein structure, which is a helix of a chain of amino acids, coiled in space into a ball?

A5. In animal cells, the storage carbohydrate is:
1. starch
2.cellulose
3.glucose
4.glycogen
A6. The main source of energy for newborn mammals is:
1.glucose
2. starch
3.glycogen
4.lactose
A7. What is an RNA monomer?
1) nitrogenous base 2) nucleotide 3) ribose 4) uracil
A8. How many types of nitrogenous bases are included in the RNA molecule?
1)5 2)2 3)3 4)4
A9. Which nitrogenous base of DNA is complementary to cytosine?
1) adenine 2) guanine 3) uracil 4) thymine
A10. Molecules are the universal biological accumulator of energy.
1).proteins 2).lipids 3).DNA 4).ATP
A11. In a DNA molecule, the number of nucleotides with guanine is 5% of the total. How many nucleotides with thymine are in this molecule
1).40% 2).45% 3).90% 4).95%
A12. What is the role of ATP molecules in a cell?

1-provide a transport function 2-transmit hereditary information

3-provide vital processes with energy 4-accelerate biochemical

reactions

IN 1. What are the functions of carbohydrates in the cell?

Catalytic 4) structural

Energy 5) storage

Motor 6) contractile

IN 2. What are the structural components of the nucleotides of the DNA molecule?

Various acids

Lipoproteins

Carbohydrate deoxyribose

Nitric acid

Phosphoric acid

IN 3. Establish a correspondence between the structure and function of organic matter and its type:

STRUCTURE AND FUNCTIONS OF SUBSTANCE

A. consist of residues of glycerol molecules and fatty acids 1. lipids

B. consist of residues of amino acid molecules 2. Proteins

B. Participate in thermoregulation

D. Protect the body from foreign substances

D. are formed due to peptide bonds.

E. They are the most energy intensive.

C1. Solve the problem.

In a DNA molecule there are 1250 nucleotides with adenine (A), which is 20% of their total number. Determine how many nucleotides with thymine (T), cytosine (C) and guanine (G) are contained separately in a DNA molecule. Explain the answer.

Total: 21 points

Evaluation criteria:

19 -21 points - "5"

13 - 18 points - "4"

9 - 12 points - "3"

1 - 8 points - "2"

Test. Molecular level. Option 2. Grade 9

A1. The share of four chemical elements accounts for 98% of the total contents of the cell. Indicate a chemical element that is NOT related to them.
1) O 2) R 3) C 4) N

A2. Children develop rickets with a lack of:
1.manganese and iron
2.calcium and phosphorus
3.copper and zinc
4.Sulfur and nitrogen
A3. Name the disaccharide.
1) lactose 2) fructose 3) starch 4) glycogen
A4. What is the name of the structure of a protein, which is a helix that a chain of amino acids is folded?
1) primary 2) secondary 3) tertiary 4) quaternary
A5. In plant cells, the storage carbohydrate is:
1. starch
2.cellulose
3.glucose
4.glycogen
A6. The greatest amount of energy is released during the decomposition of 1 gram:
1.fat
2.squirrel
3.glucose
4.carbohydrates
A7. What is a DNA monomer?
1) nitrogenous base 2) nucleotide 3) deoxyribose 4) uracil
A8. How many polynucleotide strands are included in one DNA molecule?
1)1 2)2 3)3 4)4
A9. Name a chemical compound that is present in RNA but not in DNA.
1) thymine 2) deoxmyribose 3) ribose 4) guanine
A10. Molecules are the energy source of the cell.
1).proteins 2).lipids 3).DNA 4).ATP

A11. In a DNA molecule, the number of nucleotides with cytosine is 5% of the total. How many nucleotides with thymine are in this molecule
1).40% 2).45% 3).90% 4).95%

A12. What compounds make up ATP?

1-nitrogenous base adenine, carbohydrate ribose, 3 molecules of phosphoric acid

2-nitrogen base guanine, fructose sugar, phosphoric acid residue.

3-ribose, glycerol and any amino acid

Part B (choose three correct answers from the six offered)

IN 1. Lipids perform the following functions:

Enzymatic 4) transport

Energy 5) storage

Hormonal 6) transmission of hereditary information

IN 2. What are the structural components that make up the nucleotides of an RNA molecule?

Nitrogenous bases: A, U, G, C.

Various acids

Nitrogenous bases: A, T, G, C.

Carbohydrate ribose

Nitric acid

Phosphoric acid

IN 3. Establish a correspondence between the features and the molecules for which they are characteristic.

FEATURES OF THE MOLECULE

A) dissolve well in water 1) monosaccharides

B) have a sweet taste 2) polysaccharides

C) no sweet taste

D) glucose, ribose, fructose

D) insoluble in water

E) starch, glycogen, chitin.

C1. There are 1100 nucleotides with cytosine (C) in the DNA molecule, which is 20% of their total number. Determine how many nucleotides with thymine (T), guanine (G), adenine (A) are contained separately in a DNA molecule, explain the result.

Part A - 1 point (maximum 12 points)

Part B - 2 points (maximum 6 points)

Part C - 3 points (maximum 3 points)

Total: 21 points

Evaluation criteria:

19 - 21 points - "5"

13 - 18 points - "4"

9 - 12 points - "3"

1 - 8 points - "2"

Due to the energy of light, ATP and some other molecules are formed in photosynthetic cells, which play the role of a kind of energy accumulator. An electron excited by light releases energy to phosphorylate ADP, producing ATP. An energy accumulator, in addition to ATP, is a complex organic compound - nicotinamide adenine dinucleotide phosphate, abbreviated as NADP + (as its oxidized form is designated). This compound captures light-excited electrons and a hydrogen ion (proton) and is reduced as a result to NADPH. (These abbreviations, NADP+ and NADP-N, are read respectively as NADEP and NADEP-ASH, the last letter here is the symbol of the hydrogen atom.) In fig. 35 shows a nicotinamide ring carrying an energy-rich hydrogen atom and electrons. Due to the energy of ATP and with the participation of NADPH, carbon dioxide is reduced to glucose. All these complex processes occur in plant cells in specialized cell organelles.

Practical lesson number 15.

Task for lesson number 15.

Topic: ENERGY EXCHANGE.

Relevance of the topic.

Biological oxidation is a set of enzymatic processes occurring in each cell, as a result of which molecules of carbohydrates, fats and amino acids are broken down, ultimately, to carbon dioxide and water, and the released energy is stored by the cell in the form of adenosine triphosphoric acid (ATP) and then used in the life of the organism ( biosynthesis of molecules, the process of cell division, muscle contraction, active transport, heat production, etc.). The doctor should be aware of the existence of hypoenergetic conditions in which ATP synthesis is reduced. At the same time, all vital processes that proceed with the use of energy stored in the form of macroergic bonds of ATP suffer. The most common cause of hypoenergetic states is tissue hypoxia associated with a decrease in the concentration of oxygen in the air, disruption of the cardiovascular and respiratory systems, anemia of various origins. In addition, the cause of hypoenergetic states can be hypovitaminosis associated with a violation of the structural and functional state of enzyme systems involved in the process of biological oxidation, as well as starvation, which leads to the absence of tissue respiration substrates. In addition, in the process of biological oxidation, reactive oxygen species are formed, which trigger the processes peroxidation lipids in biological membranes. It is necessary to know the mechanisms of the body's defense against these forms (enzymes, drugs that have a membrane-stabilizing effect - antioxidants).

Educational and educational goals:

The general goal of the lesson: to instill knowledge about the course of biological oxidation, as a result of which up to 70-8% of energy is formed in the form of ATP, as well as the formation of reactive oxygen species and their damaging effect on the body.

Particular goals: to be able to determine peroxidase in horseradish, potatoes; muscle succinate dehydrogenase activity.

1. Input control of knowledge:

1.1. Tests.

1.2. Oral survey.

2. Main questions of the topic:

2.1. The concept of metabolism. Anabolic and catabolic processes and their relationship.

2.2. macroergic compounds. ATP is the universal accumulator and source of energy in the body. ATP-ADP cycle. The energy charge of the cell.

2.3. Stages of metabolism. Biological oxidation (tissue respiration). Features of biological oxidation.

2.4. Primary acceptors of hydrogen protons and electrons.

2.5. Organization of the respiratory chain. Transporters in the respiratory chain (CPE).

2.6. Oxidative phosphorylation of ADP. The mechanism of conjugation of oxidation and phosphorylation. Oxidative phosphorylation coefficient (P/O).

2.7. Respiratory control. Uncoupling of respiration (oxidation) and phosphorylation (free oxidation).

2.8. Formation of toxic forms of oxygen in the CPE and neutralization of hydrogen peroxide by the enzyme peroxidase.

Laboratory and practical work.

3.1. Method for determination of peroxidase in horseradish.

3.2. Method for determination of peroxidase in potatoes.

3.3. Determination of muscle succinate dehydrogenase activity and competitive inhibition of its activity.

Output control.

4.1. Tests.

4.2. situational tasks.

5. Literature:

5.1. Lecture materials.

5.2. Nikolaev A.Ya. Biological chemistry.-M.: Higher school, 1989., P. 199-212, 223-228.

5.3. Berezov T.T., Korovkin B.F. Biological chemistry. - M.: Medicine, 1990.S.224-225.

5.4. Kushmanova O.D., Ivchenko G.M. Guide to practical exercises in biochemistry.- M.: Medicine, 1983, work. 38.

2. Main questions of the topic.

2.1. The concept of metabolism. Anabolic and catabolic processes and their relationship.

Living organisms are in constant and inextricable connection with the environment.

This connection is carried out in the process of metabolism.

Metabolism (metabolism) – the totality of all reactions in the body.

Intermediate metabolism (intracellular metabolism) - includes 2 types of reactions: catabolism and anabolism.

catabolism- the process of splitting organic substances to final products (CO 2, H 2 O and urea). This process includes metabolites formed both during digestion and during the breakdown of structural and functional components of cells.

The processes of catabolism in the cells of the body are accompanied by the consumption of oxygen, which is necessary for oxidation reactions. As a result of catabolism reactions, energy is released (exergonic reactions), which is necessary for the body for its vital activity.

Anabolism the synthesis of complex substances from simple ones. Anabolic processes use the energy released during catabolism (endergonic reactions).

Energy sources for the body are proteins, fats and carbohydrates. The energy contained in the chemical bonds of these compounds was transformed from solar energy in the process of photosynthesis.

macroergic compounds. ATP is the universal accumulator and source of energy in the body. ATP-ADP cycle. The energy charge of the cell.

ATP– is a macroergic compound containing macroergic bonds; the hydrolysis of the terminal phosphate bond releases about 20 kJ/mol of energy.

High-energy compounds include GTP, CTP, UTP, creatine phosphate, carbamoyl phosphate, etc. They are used in the body for the synthesis of ATP. For example, GTP + ADP à GDP + ATP

This process is called substrate phosphorylation– exorgonic reactions. In turn, all these high-energy compounds are formed using the free energy of the terminal phosphate group of ATP. Finally, the energy of ATP is used to perform various types of work in the body:

Mechanical (muscle contraction);

Electrical (conducting a nerve impulse);

Chemical (synthesis of substances);

Osmotic (active transport of substances across the membrane) - endergonic reactions.

Thus, ATP is the main, directly used energy donor in the body. ATP is central between endergonic and exergonic reactions.

In the human body, an amount of ATP is formed equal to the body weight, and for every 24 hours all this energy is destroyed. 1 ATP molecule "lives" in the cell for about a minute.

The use of ATP as an energy source is possible only under the condition of continuous synthesis of ATP from ADP due to the energy of oxidation of organic compounds. The ATP-ADP cycle is the main mechanism for energy exchange in biological systems, and ATP is the universal “energy currency”.

Each cell has an electrical charge, which is equal to

[ATP] + ½[ADP]

[ATP] + [ADP] + [AMP]

If the cell charge is 0.8-0.9, then in the cell the entire adenyl fund is presented in the form of ATP (the cell is saturated with energy and the process of ATP synthesis does not occur).

As energy is used, ATP is converted to ADP, the cell charge becomes 0, and ATP synthesis automatically begins.

Metabolism (metabolism) is the totality of all chemical reactions that occur in the body. All these reactions are divided into 2 groups

1. Plastic exchange(assimilation, anabolism, biosynthesis) - this is when from simple substances with energy expenditure formed (synthesized) more complex. Example:

During photosynthesis, glucose is synthesized from carbon dioxide and water.

2. Energy exchange(dissimilation, catabolism, respiration) is when complex substances break down (oxidize) to simpler ones, and at the same time energy is released necessary for life. Example:

In mitochondria, glucose, amino acids and fatty acids are oxidized by oxygen to carbon dioxide and water, and energy is generated. (cellular respiration)

The relationship of plastic and energy metabolism

Plastic metabolism provides the cell with complex organic substances (proteins, fats, carbohydrates, nucleic acids), including enzyme proteins for energy metabolism.
Energy metabolism provides the cell with energy. When doing work (mental, muscular, etc.), energy metabolism increases.

ATP- universal energy substance of the cell (universal energy accumulator). It is formed in the process of energy metabolism (oxidation of organic substances).

During energy metabolism, all substances break down, and ATP is synthesized. In this case, the energy of chemical bonds of decayed complex substances is converted into the energy of ATP, energy is stored in ATP.
During plastic exchange, all substances are synthesized, and ATP breaks down. Wherein ATP energy is consumed(the energy of ATP is converted into the energy of chemical bonds of complex substances, stored in these substances).

Choose one, the most correct option. In the process of plastic exchange
1) more complex carbohydrates are synthesized from less complex
2) fats are converted into glycerol and fatty acids
3) proteins are oxidized with the formation of carbon dioxide, water, nitrogen-containing substances
4) energy is released and ATP is synthesized

Answer

Choose three options. How does plastic exchange differ from energy exchange?
1) energy is stored in ATP molecules
2) the energy stored in ATP molecules is consumed
3) organic substances are synthesized
4) there is a breakdown of organic substances
5) end products of metabolism - carbon dioxide and water
6) as a result of metabolic reactions, proteins are formed

Answer

Choose one, the most correct option. In the process of plastic metabolism, molecules are synthesized in cells
1) proteins
2) water
3) ATP
4) inorganic substances

Answer

Choose one, the most correct option. What is the relationship between plastic and energy metabolism
1) plastic exchange supplies organic substances for energy
2) energy exchange supplies oxygen for plastic
3) plastic metabolism supplies minerals for energy
4) plastic exchange supplies ATP molecules for energy

Answer

Choose one, the most correct option. In the process of energy metabolism, in contrast to plastic,
1) the expenditure of energy contained in ATP molecules
2) energy storage in macroergic bonds of ATP molecules
3) providing cells with proteins and lipids
4) providing cells with carbohydrates and nucleic acids

Answer

1. Establish a correspondence between the characteristics of the exchange and its type: 1) plastic, 2) energy. Write the numbers 1 and 2 in the correct order.
A) oxidation of organic substances
B) the formation of polymers from monomers
B) breakdown of ATP
D) storage of energy in the cell
D) DNA replication
E) oxidative phosphorylation

Answer

2. Establish a correspondence between the characteristics of metabolism in a cell and its type: 1) energy, 2) plastic. Write down the numbers 1 and 2 in the order corresponding to the letters.
A) oxygen-free breakdown of glucose occurs
B) occurs on ribosomes, in chloroplasts
C) end products of metabolism - carbon dioxide and water
D) organic substances are synthesized
D) the energy stored in ATP molecules is used
E) energy is released and stored in ATP molecules

Answer

3. Establish a correspondence between the signs of metabolism in humans and its types: 1) plastic metabolism, 2) energy metabolism. Write the numbers 1 and 2 in the correct order.
A) substances are oxidized
B) substances are synthesized
C) energy is stored in ATP molecules
D) energy is spent
D) ribosomes are involved in the process
E) mitochondria are involved in the process

Answer

4. Establish a correspondence between the characteristics of metabolism and its type: 1) energy, 2) plastic. Write down the numbers 1 and 2 in the order corresponding to the letters.
A) DNA replication
B) protein biosynthesis
B) oxidation of organic substances
D) transcription
D) ATP synthesis
E) chemosynthesis

Answer

5. Establish a correspondence between the characteristics and types of exchange: 1) plastic, 2) energy. Write down the numbers 1 and 2 in the order corresponding to the letters.
A) energy is stored in ATP molecules
B) biopolymers are synthesized
B) carbon dioxide and water are formed
D) oxidative phosphorylation occurs
D) DNA replication occurs

Answer

Choose three processes related to energy metabolism.
1) the release of oxygen into the atmosphere
2) the formation of carbon dioxide, water, urea
3) oxidative phosphorylation
4) glucose synthesis
5) glycolysis
6) water photolysis

Answer

Choose one, the most correct option. The energy needed for muscle contraction is released when
1) breakdown of organic substances in the digestive organs
2) irritation of the muscle by nerve impulses
3) oxidation of organic substances in the muscles
4) ATP synthesis

Answer

Choose one, the most correct option. What process results in the synthesis of lipids in a cell?
1) dissimilation
2) biological oxidation
3) plastic exchange
4) glycolysis

Answer

Choose one, the most correct option. The value of plastic metabolism - the supply of the body
1) mineral salts
2) oxygen
3) biopolymers
4) energy

Answer

Choose one, the most correct option. Oxidation of organic substances in the human body occurs in
1) pulmonary vesicles when breathing
2) body cells in the process of plastic exchange
3) the process of digestion of food in the digestive tract
4) body cells in the process of energy metabolism

Answer

Choose one, the most correct option. What metabolic reactions in a cell are accompanied by energy costs?
1) the preparatory stage of energy metabolism
2) lactic acid fermentation
3) oxidation of organic substances
4) plastic exchange

Answer

1. Establish a correspondence between the processes and constituent parts of metabolism: 1) anabolism (assimilation), 2) catabolism (dissimilation). Write the numbers 1 and 2 in the correct order.
A) fermentation
B) glycolysis
B) breathing
D) protein synthesis
D) photosynthesis
E) chemosynthesis

Answer

2. Establish a correspondence between the characteristics and metabolic processes: 1) assimilation (anabolism), 2) dissimilation (catabolism). Write down the numbers 1 and 2 in the order corresponding to the letters.
A) synthesis of organic substances of the body
B) includes a preparatory stage, glycolysis and oxidative phosphorylation
C) the released energy is stored in ATP
D) water and carbon dioxide are formed
D) requires energy costs
E) occurs in chloroplasts and on ribosomes

Answer

Choose two correct answers from five and write down the numbers under which they are indicated. Metabolism is one of the main properties of living systems, it is characterized by what happens
1) selective response to external environmental influences
2) change in the intensity of physiological processes and functions with different periods of oscillation
3) transmission from generation to generation of features and properties
4) absorption of necessary substances and excretion of waste products
5) maintaining a relatively constant physical and chemical composition of the internal environment

Answer

1. All but two of the terms below are used to describe plastic exchange. Identify two terms that "fall out" from the general list, and write down the numbers under which they are indicated.
1) replication
2) duplication
3) broadcast
4) translocation
5) transcription

Answer

2. All the concepts listed below, except for two, are used to describe the plastic metabolism in the cell. Identify two concepts that “fall out” from the general list, and write down the numbers under which they are indicated.
1) assimilation
2) dissimilation
3) glycolysis
4) transcription
5) broadcast

Answer

3. The terms listed below, except for two, are used to characterize plastic exchange. Identify two terms that fall out of the general list, and write down the numbers under which they are indicated.
1) splitting
2) oxidation
3) replication
4) transcription
5) chemosynthesis

Answer

Choose one, the most correct option. The nitrogenous base adenine, ribose, and three phosphoric acid residues are
1) DNA
2) RNA
3) ATP
4) squirrel

Answer

All the signs below, except for two, can be used to characterize the energy metabolism in the cell. Identify two features that “fall out” of the general list, and write down in response the numbers under which they are indicated.
1) comes with energy absorption
2) ends in mitochondria
3) ends in ribosomes
4) is accompanied by the synthesis of ATP molecules
5) ends with the formation of carbon dioxide

Answer

Find three errors in the given text. Specify the numbers of proposals in which they are made.(1) Metabolism, or metabolism, is a set of reactions of synthesis and decay of substances of a cell and an organism, associated with the release or absorption of energy. (2) The set of reactions for the synthesis of high molecular weight organic compounds from low molecular weight compounds is referred to as plastic exchange. (3) ATP molecules are synthesized in plastic exchange reactions. (4) Photosynthesis is referred to as energy metabolism. (5) As a result of chemosynthesis, organic substances are synthesized from inorganic substances due to the energy of the Sun.

Answer