home crafts What is the process by which an ATP molecule is formed? ATP yield during aerobic breakdown of glucose to final products

What is the process by which an ATP molecule is formed? ATP yield during aerobic breakdown of glucose to final products

You figured it out for yourself from the previous article, because. it is very important. Now let's talk about how the movement of the myosin bridge is maintained, where the energy comes from for contractile processes in the muscle.

For our entire body ATP serves as one of the main sources of energy and muscle fiber is no exception. Let me remind you: - an intracellular source of energy that supports all processes occurring in the cell.

Just the breakdown of the ATP molecule and proceeds with release of energy, also during the decay, orthophosphoric acid is released, and ATP is converted to adenesine diphosphate (ADP).

When interacting with the actin filament, the heads of the myosin bridges split the ATP molecule, thereby obtaining energy for contraction.

However, it should be understood that the content of “reserve” ATP molecules in our body is small, therefore, for long-term muscle work and, especially, for intensive training, our body needs energy replenishment.

Replenishment of energy resources in the muscle is carried out in three main ways:

Breakdown of creatine phosphate. In the course of this reaction, the creatine phosphate molecule donates its phosphate group to the adenesine diphosphate (ADP) molecule, as a result of which ADP is again converted to ATP, and creatine phosphate to creatine.
However, this energy replenishment lasts a very limited time, supporting energy balance muscles only at the very beginning of their work. This is due to a small supply of creatine phosphate in muscle cells. Further, glycolysis and oxidation in mitochondria are included in the work.
Glycolysis. During this chemical process, two molecules of lactic acid are formed in the muscle - as a result of the breakdown of a glucose molecule. The breakdown of glucose occurs with the participation of ten special enzymes.
The breakdown of one molecule of glucose is capable of replenish energy reserves two molecules of ATP. Glycolysis very quickly replenishes muscle ATP reserves, tk. occurs without the participation of oxygen (anaerobic process).
In muscle tissue, the main substrate for glycolysis is glycogen. Glycogen- a complex carbohydrate branched chains units. The bulk of carbohydrates in our body accumulates in the form of glycogen, concentrated in the skeletal muscles and liver. Glycogen stores largely determine the volume of our muscles and the energy potential of the muscles.
Oxidation organic matter. This process occurs with the participation of oxygen (aerobic process), and the presence of special enzymes is also necessary for its occurrence. Delivery of oxygen takes a certain time, so this process starts after the breakdown of creatine phosphate and glycolysis.
Oxidation of organic substances is carried out in stages: the process of glycolysis starts, but still unformed molecules of lactic acid (pyruvate molecules) are sent to mitochondria for further oxidative processes, as a result of which energy is generated with the release of water (H2O) and carbon dioxide(CO2). With the help of the generated energy, 38 ATP molecules are formed.
If as a result of the anaerobic breakdown of glucose (glycolysis) 2 ATP molecules are restored, then the aerobic process (oxidation in mitochondria) is able to restore 19 times more ATP molecules.

Conclusion: the ATP molecule is the main and universal energy source for muscle activity, but the ATP reserves in the muscle fiber are small, therefore, they are constantly replenished by the breakdown of creatine phosphate, glycolysis and the oxidation of organic substances in mitochondria.

Moreover, glycolysis and oxidation are the main ways to restore ATP, and each of these methods has its own type of muscle fiber. We will talk about this in the article.

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In biology, ATP is the source of energy and the basis of life. ATP - adenosine triphosphate - is involved in metabolic processes and regulates biochemical reactions in the body.

What's this?

To understand what ATP is, chemistry will help. Chemical formula ATP molecules - C10H16N5O13P3. Remembering the full name is easy if you break it down into its component parts. Adenosine triphosphate or adenosine triphosphoric acid is a nucleotide consisting of three parts:

adenine - purine nitrogenous base;
ribose - monosaccharide related to pentoses;
three residues phosphoric acid.

Rice. 1. The structure of the ATP molecule.

A more detailed breakdown of ATP is presented in the table.

ATP was first discovered by Harvard biochemists Subbarao, Loman, and Fiske in 1929. In 1941, the German biochemist Fritz Lipmann established that ATP is the energy source of a living organism.

Energy generation

Phosphate groups are interconnected by high-energy bonds that are easily destroyed. During hydrolysis (interaction with water), the bonds of the phosphate group break down, releasing a large number of energy, and ATP is converted to ADP (adenosine diphosphoric acid).

Conditionally chemical reaction as follows:

ATP synthesis

ATP is located in the cytoplasm, nucleus, chloroplasts, and mitochondria. Synthesis of ATP in animal cage occurs in mitochondria, and in plant - in mitochondria and chloroplasts.

ATP is formed from ADP and phosphate with the expenditure of energy. This process is called phosphorylation:

ADP + H3PO4 + energy → ATP + H2O

Rice. 3. ATP formation from ADP.

In plant cells, phosphorylation occurs during photosynthesis and is called photophosphorylation. In animals, the process occurs during respiration and is called oxidative phosphorylation.

In animal cells, ATP synthesis occurs in the process of catabolism (dissimilation, energy metabolism) during the breakdown of proteins, fats, carbohydrates.

Functions

From the definition of ATP, it is clear that this molecule is capable of providing energy. In addition to energy, adenosine triphosphoric acid performs other features:

is a material for the synthesis of nucleic acids;
is part of enzymes and regulates chemical processes, accelerating or slowing down their course;
is a mediator - transmits a signal to synapses (points of contact of two cell membranes).

What have we learned?

From the 10th grade biology lesson, we learned about the structure and functions of ATP - adenosine triphosphoric acid. ATP is made up of adenine, ribose, and three phosphoric acid residues. During hydrolysis, phosphate bonds are destroyed, which releases the energy necessary for the life of organisms.

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The most important substance in the cells of living organisms is adenosine triphosphate or adenosine triphosphate. If we enter the abbreviation of this name, we get ATP (eng. ATP). This substance belongs to the group of nucleoside triphosphates and plays a leading role in the metabolic processes in living cells, being an indispensable source of energy for them.

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The discoverers of ATP were the biochemists of the Harvard School of Tropical Medicine - Yellapragada Subbarao, Karl Loman and Cyrus Fiske. The discovery occurred in 1929 and became a major milestone in the biology of living systems. Later, in 1941, the German biochemist Fritz Lipmann found that ATP in cells is the main energy carrier.

The structure of ATP

This molecule has a systematic name, which is written as follows: 9-β-D-ribofuranosyladenine-5'-triphosphate, or 9-β-D-ribofuranosyl-6-amino-purine-5'-triphosphate. What compounds are in ATP? Chemically, it is the triphosphate ester of adenosine - derivative of adenine and ribose. This substance is formed by the combination of adenine, which is a purine nitrogenous base, with the 1'-carbon of ribose via a β-N-glycosidic bond. The α-, β-, and γ-molecules of phosphoric acid are then sequentially attached to the 5'-carbon of the ribose.

Thus, the ATP molecule contains compounds such as adenine, ribose, and three phosphoric acid residues. ATP is a special compound containing bonds that release a large amount of energy. Such bonds and substances are called macroergic. During the hydrolysis of these bonds of the ATP molecule, an amount of energy from 40 to 60 kJ / mol is released, while this process is accompanied by the elimination of one or two phosphoric acid residues.

This is how these chemical reactions are written:

one). ATP + water → ADP + phosphoric acid + energy;
2). ADP + water → AMP + phosphoric acid + energy.

The energy released during these reactions is used in further biochemical processes that require certain energy inputs.

The role of ATP in a living organism. Its functions

What is the function of ATP? First of all, energy. As mentioned above, the main role of adenosine triphosphate is the energy supply of biochemical processes in a living organism. This role is due to the fact that, due to the presence of two high-energy bonds, ATP acts as an energy source for many physiological and biochemical processes that require large energy costs. Such processes are all synthesis reactions complex substances in organism. This is, first of all, the active transfer of molecules through cell membranes, including participation in the creation of intermembrane electrical potential, and the exercise of muscle contraction.

In addition to the above, we list a few more, no less important functions of ATP, such as:

How is ATP formed in the body?

Synthesis of adenosine triphosphoric acid is ongoing, because the body always needs energy for normal life. At any given moment, there is very little of this substance - about 250 grams, which are an "emergency reserve" for a "rainy day". During illness, there is an intensive synthesis of this acid, because a lot of energy is required for the functioning of the immune and excretory systems, as well as the body's thermoregulation system, which is necessary to effectively combat the onset of the disease.

Which cell has the most ATP? These are cells of muscle and nervous tissues, since energy exchange processes are most intensive in them. And this is obvious, because the muscles are involved in the movement, which requires the contraction of muscle fibers, and neurons transmit electrical impulses, without which the work of all body systems is impossible. Therefore, it is so important for the cell to maintain an unchanged and high level adenosine triphosphate.

How can adenosine triphosphate molecules be formed in the body? They are formed by the so-called phosphorylation of ADP (adenosine diphosphate). This chemical reaction looks like this:

ADP + phosphoric acid + energy→ATP + water.

Phosphorylation of ADP occurs with the participation of such catalysts as enzymes and light, and is carried out in one of three ways:

Both oxidative and substrate phosphorylation use the energy of substances oxidized in the course of such synthesis.

Conclusion

Adenosine triphosphoric acid is the most frequently updated substance in the body. How long does an adenosine triphosphate molecule live on average? In the human body, for example, its life span is less than one minute, so one molecule of such a substance is born and decays up to 3000 times per day. Amazingly, during the day the human body synthesizes about 40 kg of this substance! So great is the need for this "internal energy" for us!

The whole cycle of synthesis and further use of ATP as an energy fuel for metabolic processes in the organism of a living being is the very essence of energy metabolism in this organism. Thus, adenosine triphosphate is a kind of "battery" that ensures the normal functioning of all cells of a living organism.

Changes in creatine phosphoric acid after the slaughter of an animal were studied. The course of disintegration of creatine phosphate after the termination of the life of the animal can be observed from the curve shown in Fig. 24.
The data obtained indicate a decrease in the amount of phosphorus of creatine phosphoric acid approximately 7 hours after slaughter to 12% of the initial level. Consequently, most of the creatine phosphate is degraded before the first physically detectable signs of rigor are observed. By this time, the content of creatine phosphate in the muscles does not exceed 5% of the total acid-soluble phosphorus. Hence the conclusion: creatine phosphoric acid, taking part in the glycolytic cycle, acts only as a means of the re ATP synthesis and cannot play any other role in the changes associated with rigor mortis.

Engelhardt and Lyubimova discovered the enzymatic properties of myosin, which causes the breakdown of ATP. According to one of the authors, the following mechanism of this process takes place: during enzymatic decomposition, ATP combines with myosin, as a result of which the third particle of phosphoric acid is split off, and ADP is separated from myosin. Free myosin binds to a new ATP molecule or to actin.
In addition, these authors found that ATP, in turn, affects the mechanical properties of myosin filaments, significantly increasing their extensibility. In this regard, ATP is stronger than other organic ethers containing pyrophosphate bonds. These works allowed a new approach to the consideration of the causes of post-mortem rigor mortis.
Erdos showed that the processes of ATP breakdown and an increase in the degree of stiffness of rabbit muscles during the development of post-mortem rigor rigor run in parallel.
Taking into account the importance of ATP in the processes of glycolysis during muscle contraction and in changing the mechanical properties of myosin filaments, Erdos and Szent-Györgyi came to the conclusion that muscle stiffness depends on the lack of ATP. Similar results were obtained by other authors for muscles. various kinds animals: rabbits, cattle, horses, as well as fish.
It is known that ATP is continuously synthesized during glycolysis in the amount of 1.5 mol for each mol of lactic acid formed. However, this synthesis is balanced to some extent by the breakdown of ATP by myosin. Therefore, as long as there are unused reserves of glycogen, the complete breakdown of ATP cannot occur, and the muscle does not go into a state of rigor.
The relationship between muscle extensibility and ATP content according to Marsh is shown below. The onset of stiffness here is expressed in terms of reduced muscle extensibility (1/L) in % of the maximum.

On fig. 25 shows that changes in muscle extensibility depend not only on ATP concentration, but also on the presence of glycogen reserves in muscle tissue. In the group of animals with high glycogen stores, where the breakdown of ATP is delayed due to the longer duration of the glycolytic cycle, changes in extensibility occur in more late dates and at a lower ATP content.

Bate-Smith and Bendall found that the fast rigor phase began at 78-85% of the initial ATP content in rabbit muscle, having a final pH of 6.6, and ended when its amount reached 20% of the initial level. However, in muscles with a final pH of 5.8, critical level the ATP concentration at the beginning of the fast phase is only 30% of its initial content.
Small changes in the concentration of ATP at the end of the glycolysis process have a decisive influence on the extensibility of the muscle and the final drop in the rate of ATP conversion corresponds in each case to the onset of rigor. This position is illustrated by the curves in Fig. 25 based on data from Lowry and from Beit-Smith and Bendoll. Therefore, stiffness should depend not only on a certain level of ATP content, but also on the rate of its decrease, associated with the weakening of resynthesis and depending on the presence of glycogen reserves.
It also turned out to be possible to determine the Q10 coefficients for changes in the amount of stretch and the content of ATP and creatine phosphate in the muscles of the rabbit during its rigor mortis. These coefficients are given in table. eleven.

The exact coincidence of the Q10 coefficients for the processes of ATP breakdown and changes in muscle extensibility is additional evidence of a close relationship between them.
For the meat of cattle, the dynamics of easily hydrogenated P ATP was first traced in 1951. 26 Experimental data on changes in easily hydrolysable phosphorus in cattle meat indicate that the amount of ATP in fresh meat is on average 159.78 mg% (19.69 mg% of easily hydrolysable P). As a result of the rapidly occurring decomposition, the content of easily hydrolysable P decreases to 9.1% of the initial value by the 12th hour, i.e. over this period of time, more than 90% of the ATP contained in fresh meat decomposes.

As will be shown below, the breakdown of ATP during the growth of rigor mortis causes the transition of most of the actomyosin to an insoluble state. At the same time, due to the presence in the meat at this stage of its post-slaughter changes of residual easily hydrolysable phosphorus, highly active actomyosin cannot be formed. Subsequently, the decomposition of easily hydrolysable phosphorus slows down sharply, and in some cases practically stops by the end of the second day of storage. After the second day, there is a slight increase in its amount. In no series of experiments, the complete disappearance of easily hydrolysable phosphorus was observed during meat storage.
Data on the presence and increase in the amount of easily hydrolysable P in chilled meat of cattle were subsequently confirmed by Palmin.
As is known, in addition to adenosine triphosphoric acid (ATP), adenosine diphosphoric acid (ADP) and pyrophosphoric acid also contain easily hydrolysable phosphorus. It is very important to establish its presence and nature in chilled meat for a correct understanding of the essence of meat maturation, since the actomyosin complex dissociates into its constituent components (actin and myosin) not only in the presence of ATP, but also pyrophosphoric acid.
Therefore, in the presence of these acids, actomyosin with a high percentage of activity cannot be formed. Adenosine-diphosphoric and orthophosphoric acids do not have such properties.
From the data obtained by us, it follows that 1-2 days after slaughter, the fraction of residual phosphorus mainly consists of inorganic orthophosphate and non-hydrolysable phosphorus. Therefore, at this stage of post-slaughter storage, the presence of residual phosphorus in this fraction cannot be attributed to ATP, ADP and pyrophosphoric acid. At the same time, we proved that the increase in easily hydrolysable phosphorus on the 4th-6th day of meat ripening should be attributed to the appearance of pyrophosphoric acid or ADP in the extract, but not ATP. In view of the fact that pyrophosphoric acid has an effect similar to that of ATP on the actomyosin complex, the possibility of the resulting residual easily hydrolysable phosphorus to influence the dissociation of actomyosin into actin and myosin cannot be ruled out.
The results of the performed studies also clarify the nature of the enzymes responsible for the process of post-slaughter ATP transformations.
As already mentioned, the enzymes of glycolysis and myosin ATPase take part in these transformations. However, the latter enzyme cannot be the only one involved in the breakdown of ATP, since it catalyzes only the reaction: ATP → ADP + inorganic phosphorus (P).
Therefore, it should lead to a significant increase in the amount of ADP in the muscles after the termination of the life of the animal.
However, this does not happen. Bailey showed that after the termination of life, ADP usually does not accumulate in large quantities in rabbit muscles. Therefore, intervention in this process of myokinase is necessary. catalyzing the reaction

2ADP → ATP + AMP.

Therefore, myokinase is an additional factor that determines the rate of ATP breakdown.
Considered from this standpoint, ATP transformations convincingly explain the phenomena leading to post-mortem rigor mortis.

ATP is short for Adenosine Tri-Phosphoric Acid. And you can also find the name Adenosine triphosphate. It is a nucleoid that plays a huge role in the exchange of energy in the body. Adenosine Tri-Phosphoric acid is a universal source of energy involved in all biochemical processes of the body. This molecule was discovered in 1929 by the scientist Karl Lohmann. And its significance was confirmed by Fritz Lipmann in 1941.

Structure and formula of ATP

If we talk about ATP in more detail, then this is a molecule that gives energy to all processes occurring in the body, including it also gives energy for movement. When the ATP molecule is split, the muscle fiber contracts, as a result of which energy is released, allowing the contraction to occur. Adenosine triphosphate is synthesized from inosine - in a living organism.

In order to give the body energy, adenosine triphosphate must go through several stages. First, one of the phosphates is separated - with the help of a special coenzyme. Each of the phosphates provides ten calories. The process produces energy and produces ADP (adenosine diphosphate).

If the body needs more energy to function, then another phosphate is separated. Then AMP (adenosine monophosphate) is formed. The main source for the production of adenosine triphosphate is glucose, in the cell it breaks down into pyruvate and cytosol. Adenosine triphosphate energizes long fibers that contain the protein myosin. It is he who forms muscle cells.

At the moments when the body is resting, the chain goes to reverse side, i.e. Adenosine Tri-Phosphoric acid is formed. Again, glucose is used for this purpose. The created Adenosine triphosphate molecules will be reused as soon as it becomes necessary. When energy is not needed, it is stored in the body and released as soon as it is needed.

The ATP molecule consists of several, or rather, three components:

Ribose is a five-carbon sugar, the same one that underlies DNA.
Adenine is the combined nitrogen and carbon atoms.
Triphosphate.

At the very center of the ATP molecule is the ribose molecule, and its edge is the main one for adenosine. On the other side of the ribose is a chain of three phosphates.

ATP systems

At the same time, you need to understand that only the first two or three seconds of physical activity will be enough for ATP reserves, after which its level decreases. But at the same time, muscle work can only be carried out with the help of ATP. Thanks to special systems in the body, new ATP molecules are constantly synthesized. The inclusion of new molecules occurs depending on the duration of the load.

ATP molecules synthesize three main biochemical systems:

Phosphagen system (creatine phosphate).
Glycogen and lactic acid system.
Aerobic respiration.

Let's consider each of them separately.

Phosphagen system- if the muscles will work for a short time, but extremely intensively (about 10 seconds), the phosphagen system will be used. In this case, ADP binds to creatine phosphate. Thanks to this system, there is a constant circulation of a small amount of Adenosine triphosphate in muscle cells. Since the muscle cells themselves also have creatine phosphate, it is used to restore ATP levels after high-intensity short work. But after ten seconds, the level of creatine phosphate begins to decline - this energy is enough for a short run or an intense power load in bodybuilding.

glycogen and lactic acid- supplies energy to the body more slowly than the previous one. It synthesizes ATP, which can last for one and a half minutes of intensive work. In the process, glucose in muscle cells is converted into lactic acid by anaerobic metabolism.

Since oxygen is not used by the body in the anaerobic state, this system gives energy in the same way as in the aerobic system, but time is saved. In anaerobic mode, muscles contract extremely powerfully and quickly. Such a system could allow you to run a 400-meter sprint or a longer intense workout in the gym. But for a long time working in this way will not allow soreness in the muscles, which appears due to an excess of lactic acid.

Aerobic respiration- this system is activated if the workout lasts more than two minutes. Then the muscles begin to receive adenosine triphosphate from carbohydrates, fats and proteins. In this case, ATP is synthesized slowly, but the energy lasts for a long time - physical activity can last several hours. This is due to the fact that glucose breaks down without obstacles, it does not have any opposition that interferes with the outside - as lactic acid prevents in the anaerobic process.

The role of ATP in the body

From the previous description it is clear that the main role of adenosine triphosphate in the body is to provide energy for all the numerous biochemical processes and reactions in the body. Most energy-consuming processes in living beings occur due to ATP.

But in addition to this main function, adenosine triphosphate also performs others:

The role of ATP in the body and human life well known not only to scientists, but also to many athletes and bodybuilders, as its understanding helps to make training more effective and correctly calculate loads. For people who do strength training in the gym, sprints and other sports, it is very important to understand what exercises need to be performed at any given time. Thanks to this, you can form the desired body structure, work out the muscle structure, reduce excess weight and achieve other desired results.