ATP molecule in biology: composition, functions and role in the body. ATP and its role in metabolism Stages of ATP synthesis

Scheme 5

The transformation of substances and energy in the process of dissimilation includes the following steps:

I stage- preparatory: complex organic substances under the action of digestive enzymes break down into simple ones, while only thermal energy is released.
Proteins ® amino acids

Fats ® glycerol and fatty acids

Starch ® glucose

II stage- glycolysis (oxygen-free): carried out in the hyaloplasm, not associated with membranes; it involves enzymes; glucose is broken down:

Stage III- oxygen: carried out in mitochondria, associated with the mitochondrial matrix and the inner membrane, enzymes participate in it, pyruvic acid undergoes cleavage

CO 2 (carbon dioxide) is released from mitochondria into the environment. The hydrogen atom is included in a chain of reactions, the end result of which is the synthesis of ATP. These reactions go in the following order:

1. The hydrogen atom H, with the help of carrier enzymes, enters the inner membrane of the mitochondria, which forms cristae, where it is oxidized:

2. Proton H + (hydrogen cation) is carried by carriers to the outer surface of the membrane of the cristae. For protons, this membrane, as well as the outer membrane of the mitochondria, is impermeable, so they accumulate in the intermembrane space, forming a proton reservoir.

3. Hydrogen electrons are transferred to the inner surface of the cristae membrane and immediately attached to oxygen with the help of the oxidase enzyme, forming a negatively charged active oxygen (anion):

4. Cations and anions on both sides of the membrane create an oppositely charged electric field, and when the potential difference reaches 200 mV, the proton channel begins to operate. It occurs in the enzyme molecules of ATP synthetase, which are embedded in the inner membrane that forms the cristae.

5. Through the proton channel, H + protons rush into the mitochondria, creating a high level of energy, most of which goes to the synthesis of ATP from ADP and F (), and the H + protons themselves interact with active oxygen, forming water and molecular O 2:

Thus, O 2 entering the mitochondria during the respiration of the organism is necessary for the addition of H + protons. In its absence, the entire process in mitochondria stops, since the electron transport chain ceases to function. General reaction of stage III:

As a result of the breakdown of one glucose molecule, 38 ATP molecules are formed: at stage II - 2 ATP and at stage III - 36 ATP. The resulting ATP molecules go beyond the mitochondria and participate in all cell processes where energy is needed. Splitting, ATP gives off energy (one phosphate bond contains 46 kJ) and returns to the mitochondria in the form of ADP and F (phosphate).

The breakdown of organic substances to simpler ones with the release of energy and its storage in ATP is an energy exchange. It includes three stages - preparatory, oxygen-free and oxygen.

At the preparatory stage, although energy is released, it is not stored in ATP, but is dissipated in the form of heat.

The anoxic stage takes place in the cytoplasm and leads to the splitting of each glucose molecule into two molecules of pyruvic acid. In this case, little energy is released, so only two ATP molecules are synthesized.

The oxygen stage of energy metabolism takes place in mitochondria. Here, pyruvic acid is oxidized to carbon dioxide and water, a lot of energy is released, and about 36 ATP molecules are synthesized.

Protein biosynthesis and fat synthesis refer to plastic metabolism, when more complex ones are synthesized from simpler compounds. Such processes do not proceed with the release of energy, but with its consumption. ATP here plays the role of an energy supplier, decomposing to ADP and phosphoric acid.

In biology, the abbreviation ATP stands for organic matter (monomer) adenosine triphosphate(adenosine triphosphoric acid). According to the chemical structure, it is a nucleoside triphosphate.

ATP is made up of ribose, adenine, three phosphoric acid residues. The phosphates are connected in series. In this case, the last two are the so-called macroergic bond, the break of which provides the cell with a large amount of energy.

Thus, ATP performs in the cell energy function.

Most of the ATP molecules are formed in mitochondria in the reactions of cellular respiration. In cells, there is a constant synthesis and breakdown of a large number of molecules of adenosine triphosphoric acid.

The cleavage of phosphate groups mainly occurs with the participation of the enzyme ATPases and is a hydrolysis reaction (addition of water):

ATP + H2O = ADP + H3PO4 + E,

where E is the released energy that goes to various cellular processes (the synthesis of other organic substances, their transport, the movement of organelles and cells, thermoregulation, etc.).

According to various sources, the amount of released energy ranges from 30 to 60 kJ/mol.

ADP is adenosine diphosphate, which already contains two phosphoric acid residues.

Most often, phosphate is then added to it again to form ATP:

ADP + H3PO4 = ATP + H2O - E.

This reaction proceeds with the absorption of energy, the accumulation of which occurs as a result of a number of enzymatic reactions and ion transport processes (mainly in the matrix and on the inner membrane of mitochondria). Ultimately, energy is accumulated in the phosphate group attached to ADP.

However, another phosphate bound by a macroergic bond can be cleaved off from ADP, and AMP (adenosine monophosphate) is formed.

AMP is part of RNA. Hence, another function of adenosine triphosphoric acid is that it serves as a source of raw materials for the synthesis of a number of organic compounds.

Thus, the structural features of ATP, its functional use only as an energy source in metabolic processes, makes it possible for cells to have a single and universal system for receiving chemical energy.

Related article: Stages of Energy Metabolism

The process of phosphorylation is the reaction of transferring a phosphoryl group from one compound to another with the participation of the kinase enzyme. ATP is synthesized by oxidative and substrate phosphorylation.

Oxidative phosphorylation is the synthesis of ATP by attaching inorganic phosphate to ADP using the energy released during the oxidation of bioorganic substances.

ADP + ~P → ATP

An intermediate product of carbohydrate metabolism is phosphoenolpyruvic acid, which transfers to ADP a phosphoryl group with a high-energy bond:

2.

Second phase. After transportation, monomers (decay products of bioorganic compounds) enter the cells, where they undergo oxidation.

As a result of the oxidation of fuel molecules (amino acids, glucose, fats), the acetyl-Co-A compound is formed. During this stage, about 30% of the energy of nutrients is released.

The third stage - the Krebs cycle - is a closed system of biochemical redox reactions. The cycle is named after the English biochemist Hans Krebs, who postulated and experimentally confirmed the main reactions of aerobic oxidation. For his research, Krebs received the Nobel Prize (1953).

The cycle has two more names:

II.

This process is a dehydration reaction catalyzed by the enzyme aconitase.

This process is a hydration reaction catalyzed by the enzyme aconitase.

IV.

Reactions 4 and 5 are oxidative decarboxylation, catalyzed by isocitrate dehydrogenase, the reaction intermediate is oxalosuccinate.

This reaction is also an oxidative decarboxylation reaction, i. This is the second redox reaction:

α-Oxoglutarate + NAD + CoA Succinyl-CoA + CO2 + NADH

VII.

GTP + ADP ATP + GDP

X. Fourth redox reaction:

Four reactions of the cycle are redox, catalyzed by enzymes - dehydrogenases containing the coenzymes NAD, FAD. Coenzymes capture the resulting H + and ē and transfer them to the respiratory chain (biological oxidation chain). The elements of the respiratory chain are located on the inner membrane of the mitochondria.

The respiratory chain is a system of redox reactions, during which there is a gradual transfer of H + and ē to O2, which enters the body as a result of respiration.

ATP is produced in the respiratory chain. The main carriers of ē in the chain are iron- and copper-containing proteins (cytochromes), coenzyme Q (ubiquinone). There are 5 cytochromes in the chain (b1, c1, c, a, a3).

The prosthetic group of cytochromes b1, c1, c is iron-containing heme. The mechanism of action of these cytochromes is that they contain an iron atom with a variable valence, which can be in both an oxidized and reduced state as a result of the transfer of ē and H +:

Cytochromes a and a3 form the cytochrome oxidase complex, which is the last link in the respiratory chain.

Cytochrome oxidase contains, in addition to iron, copper with variable valence. When transporting ē from cytochrome a3 to molecular O2, the process occurs

Previous9101112131415161718192021222324Next

VIEW MORE:



Feedback

COGNITIVE

Willpower leads to action, and positive actions form a positive attitude

How the target learns about your desires before you take action.

How companies predict and manipulate habits

Healing Habit

How to get rid of resentment

Contradictory views on the qualities inherent in men

Self-confidence training

Delicious Beetroot Salad with Garlic

Still life and its pictorial possibilities

Application, how to take mummy? Shilajit for hair, face, fractures, bleeding, etc.

How to learn to take responsibility

Why do we need boundaries in relationships with children?

Reflective elements on children's clothing

How to beat your age?

Eight Unique Ways to Achieve Longevity

Classification of obesity by BMI (WHO)

Chapter 3

Axes and planes of the human body - The human body consists of certain topographic parts and areas in which organs, muscles, blood vessels, nerves, etc. are located.

Wall trimming and jamb cutting - When the house lacks windows and doors, a beautiful high porch is still only in the imagination, you have to climb the stairs from the street into the house.

Second Order Differential Equations (Price Forecast Market Model) - In simple market models, supply and demand are usually assumed to depend only on the current price of a good.

Ways of ATP synthesis in the body

The process of phosphorylation is the reaction of transferring a phosphoryl group from one compound to another with the participation of the kinase enzyme.

ATP is synthesized by oxidative and substrate phosphorylation. Oxidative phosphorylation is the synthesis of ATP by attaching inorganic phosphate to ADP using the energy released during the oxidation of bioorganic substances.

ADP + ~P → ATP

Substrate phosphorylation is the direct transfer of a phosphoryl group with a macroergic bond to ADP for ATP synthesis.

Examples of substrate phosphorylation:

1. An intermediate product of carbohydrate metabolism is phosphoenolpyruvic acid, which transfers a phosphoryl group with a high-energy bond to ADP:

The interaction of an intermediate product of the Krebs cycle - macroergic succinyl-Co-A - with ADP with the formation of one ATP molecule.

Consider the three main stages of energy release and ATP synthesis in the body.

The first stage (preparatory) includes digestion and absorption.

At this stage, 0.1% of the energy of food compounds is released.

Second phase. After transportation, monomers (decay products of bioorganic compounds) enter the cells, where they undergo oxidation. As a result of the oxidation of fuel molecules (amino acids, glucose, fats), the acetyl-Co-A compound is formed. During this stage, about 30% of the energy of nutrients is released.

The third stage - the Krebs cycle - is a closed system of biochemical redox reactions.

The cycle is named after the English biochemist Hans Krebs, who postulated and experimentally confirmed the main reactions of aerobic oxidation. For his research, Krebs received the Nobel Prize (1953). The cycle has two more names:

- the cycle of tricarboxylic acids, since it includes the reactions of the transformation of tricarboxylic acids (acids containing three carboxyl groups);

- the citric acid cycle, since the first reaction of the cycle is the formation of citric acid.

The Krebs cycle includes 10 reactions, four of which are redox.

During the reactions, 70% of the energy is released.

The biological role of this cycle is extremely great, since it is the common end point of the oxidative breakdown of all major foods.

This is the main mechanism of oxidation in the cell, figuratively it is called the metabolic "boiler". In the process of oxidation of fuel molecules (carbohydrates, amino acids, fatty acids), the body is provided with energy in the form of ATP. Fuel molecules enter the Krebs cycle after being converted into acetyl-Co-A.

In addition, the tricarboxylic acid cycle supplies intermediates for biosynthetic processes. This cycle takes place in the mitochondrial matrix.

Consider the reactions of the Krebs cycle:

The cycle begins with the condensation of the four-carbon component of oxaloacetate and the two-carbon component of acetyl-Co-A.

The reaction is catalyzed by citrate synthase and is an aldol condensation followed by hydrolysis. The intermediate product is citryl-Co-A, which is hydrolyzed to citrate and CoA:

This is the first redox reaction.

The reaction is catalyzed by an α-oxoglutarate dehydrogenase complex consisting of three enzymes:

Succinyl has a bond that is rich in energy.

Cleavage of the thioether bond of succinyl-CoA is associated with phosphorylation of guanosine diphosphate (GDP):

Succinyl-CoA + ~ P + GDP Succinate + GTP + CoA

The phosphoryl group of GTP is easily transferred to ADP to form ATP:

GTP + ADP ATP + GDP

This is the only reaction of the cycle that is a reaction of substrate phosphorylation.

This is the third redox reaction:

The Krebs cycle produces carbon dioxide, protons, and electrons.

Four reactions of the cycle are redox, catalyzed by enzymes - dehydrogenases containing the coenzymes NAD, FAD. Coenzymes capture the resulting H + and ē and transfer them to the respiratory chain (biological oxidation chain).

The elements of the respiratory chain are located on the inner membrane of the mitochondria.

The respiratory chain is a system of redox reactions, during which there is a gradual transfer of H + and ē to O2, which enters the body as a result of respiration. ATP is produced in the respiratory chain.

The main carriers of ē in the chain are iron- and copper-containing proteins (cytochromes), coenzyme Q (ubiquinone). There are 5 cytochromes in the chain (b1, c1, c, a, a3).

The prosthetic group of cytochromes b1, c1, c is iron-containing heme.

The mechanism of action of these cytochromes is that they contain an iron atom with a variable valence, which can be in both an oxidized and reduced state as a result of the transfer of ē and H +:

The final reaction that occurs on cytochrome oxidase has the form

The energy balance of the Krebs cycle and the respiratory chain is 24 ATP molecules.

Diagram of the Krebs cycle

The energy released during the breakdown of organic substances is not immediately used by the cell, but is stored in the form of high-energy compounds, usually in the form adenosine triphosphate (ATP).

ATP is classified as a mononucleotide. It consists of adenine, ribose, and three phosphoric acid residues, interconnected by macroergic bonds.

These bonds store energy, which is released when they are broken:

ATP + H2O → ADP + H3PO4 + Q1,
ADP + H2O → AMP + H3PO4 + Q2,
AMP + H2O → adenine + ribose + H3PO4 + Q3,

where ATP is adenosine triphosphoric acid; ADP - acenosine diphosphoric acid; AMP - adenosine monophosphoric acid; Q1 = Q2 = 30.6 kJ; Q3 = 13.8 kJ.

The supply of ATP in the cell is limited and replenished due to the process of phosphorylation - the addition of a phosphoric acid residue to ADP (ADP + F → ATP).

It occurs with varying intensity during respiration, fermentation, and photosynthesis. ATP is renewed extremely quickly (in humans, the lifespan of one ATP molecule is less than 1 minute).

The energy stored in ATP molecules is used by the body in anabolic reactions (biosynthesis reactions).

The ATP molecule serves as a universal store and carrier of energy for all living beings.

Anatomy and physiology of the central nervous system

4. Metabolism of fats, their biological role, heat capacity, participation in metabolism.

Energy value of fats. Fat deposits

Fats are organic compounds that are part of animal and plant tissues and consist mainly of triglycerides (esters of glycerol and various fatty acids). In addition to triglycerides, fats contain substances ...

Effect of organic fertilizers on soil microbiota

2.

The role of microorganisms in the cycle of substances in nature

The chemical activity of microorganisms is manifested in the continuous cycle of nitrogen, phosphorus, sulfur, carbon and other substances. With the most active, wide participation of microorganisms in nature, mainly in the soil and hydrosphere ...

Hormone oxytocin

1.

Chemical structure and synthesis of oxytocin

Oxytocin is not its own hormone of the neurohypophysis, but only accumulates in it, moving along the axons of the hypothalamic-pituitary bundle from the nuclei of the anterior hypothalamus - supraoptic and paraventricular ...

3.

Reactivity of substances, analysis and synthesis

Natural science at the molecular level

3. Reactivity of substances, analysis and synthesis

Dependence of the level of thyroid-stimulating and thyroid hormones on thyroid diseases

2.5 Influence of substances on the synthesis of thyroid hormones

At present, it is believed that the influence on the synthesis of various substances is of a mixed nature.

This thesis is proved in the article by R.V.

Kubasova, E.D…

Microorganisms in the cycle of substances in nature

The role of microorganisms in the cycle of substances in nature

With the help of microorganisms, organic compounds of plant and animal origin are mineralized to carbon, nitrogen, sulfur, phosphorus, iron, etc.

The carbon cycle. Plants take an active part in the carbon cycle...

Microorganisms isolated from various natural fats

1.1 Structure of fatty substances

Fats are non-volatile substances and, when heated to 250-300 ° C, they decompose with the formation of volatile substances that are released in the form of vapors, gases and smoke.

Fats are poor conductors of heat...

Chapter 4

Protein metabolism. Fat metabolism. The exchange of carbohydrates. The liver, its role in metabolism

4.3 The role of the liver in metabolism

Considering the metabolism of proteins, fats and carbohydrates, we have repeatedly affected the liver.

The liver is the most important organ for protein synthesis. It forms all of the blood albumin, the bulk of the coagulation factors ...

Basic principles of nutrition

7. The role of minerals in human nutrition

Depending on the amount of minerals in the human body and in food products, they are divided into macro- and microelements.

The former include calcium, potassium, magnesium, sodium, phosphorus, chlorine, sulfur ...

The role of microorganisms in the cycle of chemical elements in nature

4. The role of microorganisms in the sulfur cycle in nature, their significance in the transformation of substances and practical use

The cycle of sulfur is carried out as a result of the vital activity of bacteria that oxidize or restore it.

Sulfur recovery processes occur in several ways. Under the influence of putrefactive bacteria - Clostridium ...

4.2 Carotenoids. Their structure, functions and physiological role

Carotenoids - fat-soluble pigments of yellow, orange, red color - are present in the chloroplasts of all plants. They are also part of the chromoplasts in non-green parts of plants, for example, in carrot roots ...

Photosynthesis as the basis of the energy of the biosphere

4.3 Phycobilins.

Their structure, functions and physiological role

Blue-green algae (cyanobacteria), red algae and some marine cryptomonads, in addition to chlorophyll a and carotenoids, contain phycobilin pigments ...

Energy metabolism of microorganisms

1.

General concepts of metabolism and energy

All living organisms can only use chemically bound energy. Every substance has a certain amount of potential energy. The main material carriers of its chemical bonds ...

Main source of energy for the cell are nutrients: carbohydrates, fats and proteins, which are oxidized with the help of oxygen. Almost all carbohydrates, before reaching the cells of the body, are converted into glucose due to the work of the gastrointestinal tract and liver. Along with carbohydrates, proteins are also broken down - to amino acids and lipids - to fatty acids. In the cell, nutrients are oxidized under the action of oxygen and with the participation of enzymes that control the reactions of energy release and its utilization.

Almost all oxidative reactions occur in mitochondria, and the released energy is stored in the form of a macroergic compound - ATP. In the future, it is ATP, and not nutrients, that is used to provide energy for intracellular metabolic processes.

ATP molecule contains: (1) the nitrogenous base adenine; (2) pentose carbohydrate ribose, (3) three phosphoric acid residues. The last two phosphates are connected to each other and to the rest of the molecule by macroergic phosphate bonds, indicated by the symbol ~ in the ATP formula. Subject to the physical and chemical conditions characteristic of the body, the energy of each such bond is 12,000 calories per 1 mol of ATP, which is many times higher than the energy of an ordinary chemical bond, which is why phosphate bonds are called macroergic. Moreover, these bonds are easily destroyed, providing intracellular processes with energy as soon as the need arises.

When released ATP energy donates a phosphate group and is converted to adenosine diphosphate. The released energy is used for almost all cellular processes, for example, in biosynthesis reactions and during muscle contraction.

Scheme of the formation of adenosine triphosphate in the cell, showing the key role of mitochondria in this process.
GI - glucose; FA - fatty acids; AA is an amino acid.

Replenishment of ATP reserves occurs by recombining ADP with a phosphoric acid residue at the expense of the energy of nutrients. This process is repeated over and over again. ATP is constantly consumed and accumulated, which is why it is called the energy currency of the cell. The turnover time of ATP is only a few minutes.

The role of mitochondria in the chemical reactions of ATP formation. When glucose enters the cell, under the action of cytoplasmic enzymes it turns into pyruvic acid (this process is called glycolysis). The energy released in this process is used to convert a small amount of ADP to ATP, less than 5% of the total energy reserves.

95% is carried out in mitochondria. Pyruvic acid, fatty acids and amino acids, formed respectively from carbohydrates, fats and proteins, are eventually converted in the mitochondrial matrix into a compound called acetyl-CoA. This compound, in turn, enters into a series of enzymatic reactions, collectively known as the tricarboxylic acid cycle or the Krebs cycle, to give up its energy.

In a loop tricarboxylic acids acetyl-CoA splits into hydrogen atoms and carbon dioxide molecules. Carbon dioxide is removed from the mitochondria, then from the cell by diffusion and excreted from the body through the lungs.

hydrogen atoms are chemically very active and therefore immediately react with oxygen diffusing into the mitochondria. The large amount of energy released in this reaction is used to convert many ADP molecules into ATP. These reactions are quite complex and require the participation of a huge number of enzymes that make up the mitochondrial cristae. At the initial stage, an electron is split off from the hydrogen atom, and the atom turns into a hydrogen ion. The process ends with the addition of hydrogen ions to oxygen. As a result of this reaction, water and a large amount of energy are formed that are necessary for the operation of ATP synthetase, a large globular protein that acts as tubercles on the surface of mitochondrial cristae. Under the action of this enzyme, which uses the energy of hydrogen ions, ADP is converted into ATP. New ATP molecules are sent from the mitochondria to all parts of the cell, including the nucleus, where the energy of this compound is used to provide a variety of functions.
This process ATP synthesis generally called the chemiosmotic mechanism of ATP formation.

The use of mitochondrial adenosine triphosphate for the implementation of three important functions of the cell:
membrane transport, protein synthesis and muscle contraction.

Millions of biochemical reactions take place in any cell of our body. They are catalyzed by a variety of enzymes that often require energy. Where does the cell take it? This question can be answered if we consider the structure of the ATP molecule - one of the main sources of energy.

ATP is a universal source of energy

ATP stands for adenosine triphosphate, or adenosine triphosphate. Matter is one of the two most important sources of energy in any cell. The structure of ATP and the biological role are closely related. Most biochemical reactions can only take place with the participation of molecules of a substance, especially this applies. However, ATP is rarely directly involved in the reaction: for any process to take place, energy is needed that is contained precisely in adenosine triphosphate.

The structure of the molecules of the substance is such that the bonds formed between the phosphate groups carry a huge amount of energy. Therefore, such bonds are also called macroergic, or macroenergetic (macro=many, large number). The term was first introduced by the scientist F. Lipman, and he also suggested using the icon ̴ to designate them.

It is very important for the cell to maintain a constant level of adenosine triphosphate. This is especially true for muscle cells and nerve fibers, because they are the most energy-dependent and need a high content of adenosine triphosphate to perform their functions.

The structure of the ATP molecule

Adenosine triphosphate is made up of three elements: ribose, adenine, and

Ribose- a carbohydrate that belongs to the group of pentoses. This means that ribose contains 5 carbon atoms, which are enclosed in a cycle. Ribose is connected to adenine by a β-N-glycosidic bond on the 1st carbon atom. Also, phosphoric acid residues on the 5th carbon atom are attached to the pentose.

Adenine is a nitrogenous base. Depending on which nitrogenous base is attached to the ribose, GTP (guanosine triphosphate), TTP (thymidine triphosphate), CTP (cytidine triphosphate) and UTP (uridine triphosphate) are also isolated. All these substances are similar in structure to adenosine triphosphate and perform approximately the same functions, but they are much less common in the cell.

Residues of phosphoric acid. A maximum of three phosphoric acid residues can be attached to a ribose. If there are two or only one of them, then, respectively, the substance is called ADP (diphosphate) or AMP (monophosphate). It is between the phosphorus residues that macroenergetic bonds are concluded, after the rupture of which from 40 to 60 kJ of energy is released. If two bonds are broken, 80, less often - 120 kJ of energy is released. When the bond between the ribose and the phosphorus residue is broken, only 13.8 kJ is released, therefore, there are only two high-energy bonds in the triphosphate molecule (P ̴ P ̴ P), and one in the ADP molecule (P ̴ P).

What are the structural features of ATP. Due to the fact that a macroenergetic bond is formed between phosphoric acid residues, the structure and functions of ATP are interconnected.

The structure of ATP and the biological role of the molecule. Additional functions of adenosine triphosphate

In addition to energy, ATP can perform many other functions in the cell. Along with other nucleotide triphosphates, triphosphate is involved in the construction of nucleic acids. In this case, ATP, GTP, TTP, CTP and UTP are the suppliers of nitrogenous bases. This property is used in processes and transcription.

ATP is also required for the operation of ion channels. For example, the Na-K channel pumps 3 molecules of sodium out of the cell and pumps 2 molecules of potassium into the cell. Such an ion current is needed to maintain a positive charge on the outer surface of the membrane, and only with the help of adenosine triphosphate can the channel function. The same applies to proton and calcium channels.

ATP is a precursor of the second messenger cAMP (cyclic adenosine monophosphate) - cAMP not only transmits the signal received by the cell membrane receptors, but is also an allosteric effector. Allosteric effectors are substances that speed up or slow down enzymatic reactions. So, cyclic adenosine triphosphate inhibits the synthesis of an enzyme that catalyzes the breakdown of lactose in bacterial cells.

The adenosine triphosphate molecule itself can also be an allosteric effector. Moreover, in such processes, ADP acts as an ATP antagonist: if triphosphate accelerates the reaction, then diphosphate slows down, and vice versa. These are the functions and structure of ATP.

How is ATP formed in the cell

The functions and structure of ATP are such that the molecules of the substance are quickly used and destroyed. Therefore, the synthesis of triphosphate is an important process in the formation of energy in the cell.

There are three most important ways to synthesize adenosine triphosphate:

1. Substrate phosphorylation.

2. Oxidative phosphorylation.

3. Photophosphorylation.

Substrate phosphorylation is based on multiple reactions occurring in the cytoplasm of the cell. These reactions are called glycolysis - the anaerobic stage. As a result of 1 glycolysis cycle, two molecules are synthesized from 1 glucose molecule, which are further used for energy production, and two ATP are also synthesized.

• C 6 H 12 O 6 + 2ADP + 2Fn --> 2C 3 H 4 O 3 + 2ATP + 4H.

Cell respiration

Oxidative phosphorylation is the formation of adenosine triphosphate by the transfer of electrons along the electron transport chain of the membrane. As a result of this transfer, a proton gradient is formed on one of the sides of the membrane, and with the help of the protein integral set of ATP synthase, molecules are built. The process takes place on the mitochondrial membrane.

The sequence of steps of glycolysis and oxidative phosphorylation in mitochondria makes up the overall process called respiration. After a complete cycle, 36 ATP molecules are formed from 1 glucose molecule in the cell.

Photophosphorylation

The process of photophosphorylation is the same oxidative phosphorylation with only one difference: photophosphorylation reactions occur in the chloroplasts of the cell under the action of light. ATP is produced during the light stage of photosynthesis, the main energy-producing process in green plants, algae, and some bacteria.

In the process of photosynthesis, electrons pass through the same electron transport chain, resulting in the formation of a proton gradient. The concentration of protons on one side of the membrane is the source of ATP synthesis. The assembly of molecules is carried out by the enzyme ATP synthase.

The average cell contains 0.04% adenosine triphosphate of the total mass. However, the highest value is observed in muscle cells: 0.2-0.5%.

There are about 1 billion ATP molecules in a cell.

Each molecule lives no more than 1 minute.

One molecule of adenosine triphosphate is renewed 2000-3000 times a day.

In total, the human body synthesizes 40 kg of adenosine triphosphate per day, and at each time point the supply of ATP is 250 g.

Conclusion

The structure of ATP and the biological role of its molecules are closely related. The substance plays a key role in life processes, because the macroergic bonds between phosphate residues contain a huge amount of energy. Adenosine triphosphate performs many functions in the cell, and therefore it is important to maintain a constant concentration of the substance. Decay and synthesis proceed at a high speed, since the energy of bonds is constantly used in biochemical reactions. It is an indispensable substance of any cell of the body. That, perhaps, is all that can be said about the structure of ATP.

Adenosine triphosphoric acid-ATP- an obligatory energy component of any living cell. ATP is also a nucleotide consisting of the nitrogenous base of adenine, the sugar of ribose, and three residues of the phosphoric acid molecule. This is an unstable structure. In metabolic processes, phosphoric acid residues are sequentially split off from it by breaking the energy-rich, but fragile bond between the second and third phosphoric acid residues. The detachment of one molecule of phosphoric acid is accompanied by the release of about 40 kJ of energy. In this case, ATP passes into adenosine diphosphoric acid (ADP), and with further cleavage of the phosphoric acid residue from ADP, adenosine monophosphoric acid (AMP) is formed.

Schematic diagram of the structure of ATP and its transformation into ADP ( T.A. Kozlova, V.S. Kuchmenko. Biology in tables. M., 2000 )

Consequently, ATP is a kind of energy accumulator in the cell, which is "discharged" when it is split. The breakdown of ATP occurs during the reactions of synthesis of proteins, fats, carbohydrates and any other vital functions of cells. These reactions go with the absorption of energy, which is extracted during the breakdown of substances.

ATP is synthesized in mitochondria in several stages. The first one is preparatory - proceeds stepwise, with the involvement of specific enzymes at each step. In this case, complex organic compounds are broken down to monomers: proteins - to amino acids, carbohydrates - to glucose, nucleic acids - to nucleotides, etc. Breaking bonds in these substances is accompanied by the release of a small amount of energy. The resulting monomers under the action of other enzymes can undergo further decomposition with the formation of simpler substances up to carbon dioxide and water.

Scheme Synthesis of ATP in the mitochondria of the cell

EXPLANATIONS TO THE SCHEME CONVERSION OF SUBSTANCES AND ENERGY IN THE PROCESS OF DISSIMILATION

Stage I - preparatory: complex organic substances under the action of digestive enzymes break down into simple ones, while only thermal energy is released.
Proteins -> amino acids
Fats- > glycerin and fatty acids
Starch ->glucose

Stage II - glycolysis (oxygen-free): carried out in the hyaloplasm, not associated with membranes; it involves enzymes; glucose is broken down:

In yeast fungi, the glucose molecule, without the participation of oxygen, is converted into ethyl alcohol and carbon dioxide (alcoholic fermentation):

In other microorganisms, glycolysis can be completed with the formation of acetone, acetic acid, etc. In all cases, the breakdown of one glucose molecule is accompanied by the formation of two ATP molecules. During the oxygen-free breakdown of glucose in the form of a chemical bond, 40% of the anergy is retained in the ATP molecule, and the rest is dissipated in the form of heat.

Stage III - hydrolysis (oxygen): carried out in mitochondria, associated with the mitochondrial matrix and the inner membrane, enzymes participate in it, lactic acid undergoes cleavage: CsH6Oz + ZH20 --> 3CO2 + 12H. CO2 (carbon dioxide) is released from the mitochondria into the environment. The hydrogen atom is included in a chain of reactions, the end result of which is the synthesis of ATP. These reactions go in the following order:

1. The hydrogen atom H, with the help of carrier enzymes, enters the inner membrane of mitochondria, which forms cristae, where it is oxidized: H-e--> H+

2. Hydrogen proton H+(cation) is carried by carriers to the outer surface of the membrane of the cristae. For protons, this membrane is impermeable, so they accumulate in the intermembrane space, forming a proton reservoir.

3. Hydrogen electrons e are transferred to the inner surface of the cristae membrane and immediately attach to oxygen with the help of the oxidase enzyme, forming a negatively charged active oxygen (anion): O2 + e--> O2-

4. Cations and anions on both sides of the membrane create an oppositely charged electric field, and when the potential difference reaches 200 mV, the proton channel begins to operate. It occurs in the enzyme molecules of ATP synthetase, which are embedded in the inner membrane that forms the cristae.

5. Hydrogen protons through the proton channel H+ rush inside the mitochondria, creating a high level of energy, most of which goes to the synthesis of ATP from ADP and P (ADP + P -\u003e ATP), and protons H+ interact with active oxygen, forming water and molecular 02:
(4Н++202- -->2Н20+02)

Thus, O2, which enters the mitochondria during the respiration of the organism, is necessary for the addition of hydrogen protons H. In its absence, the entire process in mitochondria stops, since the electron transport chain ceases to function. General reaction of stage III:

(2CsHbOz + 6Oz + 36ADP + 36F ---> 6C02 + 36ATP + + 42H20)

As a result of the breakdown of one glucose molecule, 38 ATP molecules are formed: at stage II - 2 ATP and at stage III - 36 ATP. The resulting ATP molecules go beyond the mitochondria and participate in all cell processes where energy is needed. Splitting, ATP gives off energy (one phosphate bond contains 40 kJ) and returns to the mitochondria in the form of ADP and F (phosphate).