Each of our movement or thought requires energy from the body. This force is stored by every cell of the body and accumulates it in biomolecules with the help of macroergic bonds. It is these battery molecules that provide all life processes. The constant exchange of energy within the cells determines life itself. What are these biomolecules with macroergic bonds, where do they come from, and what happens to their energy in every cell of our body - this is discussed in the article.
Biological mediators
In any organism, energy from an energy-generating agent to a biological energy consumer does not pass directly. When the intramolecular bonds of food products are broken, the potential energy of chemical compounds is released, which far exceeds the ability of intracellular enzymatic systems to use it. That is why in biological systems the release of potential chemicals occurs stepwise with their gradual transformation into energy and its accumulation in macroergic compounds and bonds. And it is the biomolecules that are capable of such an accumulation of energy that are called high-energy.
What bonds are called macroergic?
The free energy level of 12.5 kJ/mol, which is formed during the formation or decay of a chemical bond, is considered normal. When, during the hydrolysis of certain substances, free energy is formed more than 21 kJ / mol, then this is called macroergic bonds. They are denoted by the tilde symbol - ~. In contrast to physical chemistry, where a macroergic bond means a covalent bond of atoms, in biology they mean the difference between the energy of the initial agents and their decay products. That is, the energy is not localized in a specific chemical bond of atoms, but characterizes the entire reaction. In biochemistry, they talk about chemical conjugation and the formation of a macroergic compound.
Universal Bio Energy Source
All living organisms on our planet have one universal element of energy storage - this is the macroergic bond ATP - ADP - AMP (adenosine tri, di, monophosphoric acid). These are biomolecules that consist of a nitrogen-containing adenine base attached to a ribose carbohydrate and attached phosphoric acid residues. Under the action of water and a restriction enzyme, an adenosine triphosphate molecule (C10H16N5O 13P3) can decompose into an adenosine diphosphoric acid molecule and orthophosphate acid. This reaction is accompanied by the release of free energy of the order of 30.5 kJ/mol. All life processes in every cell of our body occur when energy is accumulated in ATP and used when it is broken.bonds between orthophosphoric acid residues.
Donor and acceptor
High-energy compounds also include substances with long names that can form ATP molecules in hydrolysis reactions (for example, pyrophosphoric and pyruvic acids, succinyl coenzymes, aminoacyl derivatives of ribonucleic acids). All these compounds contain phosphorus (P) and sulfur (S) atoms, between which there are high-energy bonds. It is the energy that is released when the high-energy bond in ATP (donor) is broken that is absorbed by the cell during the synthesis of its own organic compounds. And at the same time, the reserves of these bonds are constantly replenished with the accumulation of energy (acceptor) released during the hydrolysis of macromolecules. In every cell of the human body, these processes occur in mitochondria, while the duration of the existence of ATP is less than 1 minute. During the day, our body synthesizes about 40 kilograms of ATP, which go through up to 3 thousand cycles of decay each. And at any given moment, about 250 grams of ATP is present in our body.
Functions of high energy biomolecules
In addition to the function of the donor and acceptor of energy in the processes of decomposition and synthesis of macromolecular compounds, ATP molecules play several other very important roles in cells. The energy of breaking macroergic bonds is used in the processes of heat generation, mechanical work, accumulation of electricity, and luminescence. At the same time, the transformationthe energy of chemical bonds into thermal, electrical, mechanical at the same time serves as a stage of energy exchange with subsequent storage of ATP in the same macro-energetic bonds. All these processes in the cell are called plastic and energy exchanges (diagram in the figure). ATP molecules also act as coenzymes, regulating the activity of certain enzymes. In addition, ATP can also be a mediator, a signaling agent in the synapses of nerve cells.
The flow of energy and matter in the cell
Thus, ATP in the cell occupies a central and main place in the exchange of matter. There are quite a lot of reactions by means of which ATP arises and breaks down (oxidative and substrate phosphorylation, hydrolysis). The biochemical reactions of the synthesis of these molecules are reversible; under certain conditions, they are shifted in the cells in the direction of synthesis or decay. The paths of these reactions differ in the number of transformations of substances, the type of oxidative processes, and in the ways of conjugation of energy-supplying and energy-consuming reactions. Each process has clear adaptations to the processing of a particular type of "fuel" and its efficiency limits.
Performance evaluation
Indicators of the efficiency of energy conversion in biosystems are small and are estimated in standard values of the efficiency factor (the ratio of useful work spent on work to the total energy expended). But here, to ensure the performance of biological functions, the costs are very high. For example, a runner, in terms of a unit of mass, spends so muchenergy, how much and a big ocean liner. Even at rest, maintaining the life of an organism is hard work, and about 8 thousand kJ / mol is spent on it. At the same time, about 1.8 thousand kJ / mol is spent on protein synthesis, 1.1 thousand kJ / mol on the work of the heart, but up to 3.8 thousand kJ / mol on ATP synthesis.
Adenylate cell system
This is a system that includes the sum of all ATP, ADP and AMP in a cell in a specific period of time. This value and the ratio of components determines the energy status of the cell. The system is evaluated in terms of the energy charge of the system (the ratio of phosphate groups to the adenosine residue). If only ATP is present in the cell macroergic compounds - it has the highest energy status (index -1), if only AMP - the minimum status (index - 0). In living cells, indicators of 0.7-0.9 are usually maintained. The stability of the energy status of the cell determines the rate of enzymatic reactions and the maintenance of an optimal level of vital activity.
And a little about power stations
As already mentioned, ATP synthesis occurs in specialized cell organelles - mitochondria. And today among biologists there are disputes about the origin of these amazing structures. Mitochondria are the power plants of the cell, "fuel" for which are proteins, fats, glycogen, and electricity - ATP molecules, the synthesis of which takes place with the participation of oxygen. We can say that we breathe in order for the mitochondria to work. The more work to docells, the more energy they need. Read - ATP, which means - mitochondria.
For example, a professional athlete has about 12% mitochondria in their skeletal muscles, while a non-athletic layman has half as much. But in the heart muscle, their rate is 25%. Modern training methods for athletes, especially marathon runners, are based on MOC (maximum oxygen consumption), which directly depends on the number of mitochondria and the ability of muscles to perform prolonged loads. Leading training programs for professional sports are aimed at stimulating the synthesis of mitochondria in muscle cells.
