MITOCHONDRIA (mitochondria; Greek, mitos thread + chondrion grain) - organelles present in the cytoplasm of cells of animal and plant organisms. M. take part in the processes of respiration and oxidative phosphorylation, produce the energy necessary for the functioning of the cell, thus representing its "power stations".

The term "mitochondria" was proposed in 1894 by S. Benda. In the mid-30s. 20th century it was possible for the first time to isolate M. from liver cells, which made it possible to study these structures by biochemistry methods. In 1948 G. Hogeboom received definitive evidence that M. really are the centers of cellular respiration. Significant advances in the study of these organelles were made in the 60-70s. in connection with the use of methods of electron microscopy and molecular biology.

M.'s shape varies from almost round to strongly elongated, having the form of filaments (Fig. 1), their size ranges from 0.1 to 7 microns. The amount of M. in a cell depends on the type of tissue and the functional state of the organism. So, in spermatozoa M.'s number is small - approx. 20 (per cell), the epithelial cells of mammalian renal tubules contain up to 300 in each, and the giant amoeba (Chaos chaos) has 500,000 mitochondria. One cell of the rat liver contains approx. 3000 M., however, in the process of starvation of an animal, the number of M. can be reduced to 700. Usually M. are distributed in the cytoplasm quite evenly, but in the cells of certain tissues M. can be permanently localized in areas that are especially in need of energy. For example, in skeletal muscle M. are often in contact with the contractile areas of myofibrils, forming regular three-dimensional structures. In spermatozoa, M. form a spiral sheath around the axial filament of the tail, which is probably associated with the ability to use the ATP energy synthesized in M. for tail movements. In axons, M. are concentrated near synaptic endings, where the process of transmission of nerve impulses occurs, accompanied by energy consumption. In the cells of the epithelium of the renal tubules M. are associated with protrusions of the basal cell membrane. This is due to the need for a constant and intensive supply of energy to the process of active transfer of water and substances dissolved in it, which takes place in the kidneys.

Electron microscopically, it has been established that M. contains two membranes - an external and an internal one. The thickness of each membrane is approx. 6 nm, the distance between them is 6-8 nm. The outer membrane is smooth, the inner membrane forms complex outgrowths (cristae) protruding into the mitochondrial cavity (Fig. 2). The inner space of M. is called the matrix. Membranes are a film of compactly packed molecules of proteins and lipids, while the matrix is ​​similar to a gel and contains soluble proteins, phosphates and other chemicals. connections. Usually the matrix looks homogeneous, only in some cases it is possible to find thin threads, tubes and granules containing calcium and magnesium ions in it.

Of the structural features of the inner membrane, it should be noted that it contains spherical particles of approx. 8-10 nm in diameter, sitting on a short stalk and sometimes protruding into the matrix. These particles were discovered in 1962 by H. Fernandez-Moran. They consist of a protein with ATPase activity, designated F1. The protein attaches to the inner membrane only from the side facing the matrix. Particles F1 are located at a distance of 10 nm from each other, and each M. contains 10 4 -10 5 such particles.

The cristae and internal membranes of M. contain the majority of respiratory enzymes (see), the respiratory enzymes are organized into compact ensembles, distributed at regular intervals in M.'s cristae at a distance of 20 nm from each other.

M. of almost all types of cells of animals and plants are built according to a single principle, however, deviations in details are possible. So, the cristae can be located not only across the long axis of the organoid, but also longitudinally, for example, in the M. of the synaptic zone of the axon. In some cases, the cristae can branch. In M. of the simplest organisms, certain insects, and in the cells of the glomerular zone of the adrenal glands, the cristae have the form of tubules. The number of crystals is different; thus, in M., there are very few cristae and germ cells of the liver, and they are short, while the matrix is ​​abundant; in M., the muscle cells of the crista are numerous, but the matrix is ​​small. It is believed that the number of cristae correlates with the oxidative activity of M.

In the inner membrane of M., three processes are carried out in parallel: the oxidation of the substrate of the Krebs cycle (see the tricarboxylic acid cycle), the transfer of electrons released during this and the accumulation of energy through the formation of high-energy bonds of adenosine triphosphate (see. Adenosine phosphoric acids). M.'s main function is the conjugation of ATP synthesis (from ADP and inorganic phosphorus) and the aerobic oxidation process (see biological oxidation). The energy accumulated in ATP molecules can be transformed into mechanical (in muscles), electrical (nervous system), osmotic (kidneys), etc. The processes of aerobic respiration (see biological oxidation) and associated oxidative phosphorylation (see) are the main functions of M. In addition, in the outer membrane of M., oxidation of fatty to-t, phospholipids and some other compounds can occur.

In 1963, Nass and Nass (M. Nass, S. Nass) established that M. contains DNA (one or more molecules). All mitochondrial DNA from animal cells investigated so far consists of covalently closed rings with a diameter of. OK. 5 nm. In plants, mitochondrial DNA is much longer and does not always have a ring shape. Mitochondrial DNA differs in many ways from nuclear DNA. Replication of DNA occurs by the usual mechanism, but does not coincide in time with the replication of nuclear DNA. The amount of genetic information contained in the mitochondrial DNA molecule is apparently insufficient to encode all the proteins and enzymes contained in M. Mitochondrial genes encode mainly structural membrane proteins and proteins involved in mitochondrial morphogenesis. M. have their own transport RNA and synthetases, they contain all the components necessary for protein synthesis; their ribosomes are smaller than cytoplasmic and more like bacterial ribosomes.

M.'s life span is relatively short. Thus, the renewal time for half of the amount of M. is 9.6-10.2 days for the liver, and 12.4 days for the kidney. Replenishment of M.'s population occurs, as a rule, from preexisting (maternal) M. by their division or budding.

It has long been suggested that in the process of evolution M. arose, probably through the endosymbiosis of primitive nucleated cells with bacterio-like organisms. There is a large amount of evidence for this: the presence of its own DNA, which is more similar to the DNA of bacteria than to the DNA of the cell nucleus; the presence of ribosomes in M.; synthesis of DNA-dependent RNA; sensitivity of mitochondrial proteins to the antibacterial drug chloramphenicol; similarity with bacteria in the implementation of the respiratory chain; morfol., biochem, and fiziol, differences between the inner and outer membrane. According to the symbiotic theory, the host cell is considered as an anaerobic organism, the source of energy for which is glycolysis (flowing in the cytoplasm). In the "symbiont" the Krebs cycle and the respiratory chain are realized; he is capable of respiration and oxidative phosphorylation (see).

M. are very labile intracellular organelles, reacting earlier than others to the emergence of any patol, conditions. Changes in the number of M. in a cell (or rather, in their populations) or changes in their structure are possible. For example, during starvation, the action of ionizing radiation, M.'s number decreases. Structural changes usually consist in the swelling of the entire organoid, clarification of the matrix, destruction of the cristae, and disruption of the integrity of the outer membrane.

The swelling is accompanied by a significant change in M.'s volume. In particular, with myocardial ischemia, M.'s volume increases 10 times or more. There are two types of swelling: in one case, it is associated with a change in osmotic pressure inside the cell, in other cases - with changes in cellular respiration associated with enzymatic reactions and primary functional disorders that cause changes in water metabolism. In addition to swelling, M. vacuolization can occur.

Regardless of the reasons causing patol, the state (hypoxia, hyperfunction, intoxication), M.'s changes are rather stereotyped and nonspecific.

Such changes in the structure and functions of M. are observed, to-rye, apparently, became the cause of the disease. In 1962 R. Luft described a case of "mitochondrial disease". A patient with a sharply increased metabolic rate (with normal thyroid function) underwent a puncture of the skeletal muscle and found an increased number of M., as well as a violation of the structure of the cristae. Defective mitochondria in liver cells were also observed in severe thyrotoxicosis. Grapes (J. Vinograd) et al. (from 1937 to 1969) found that in patients with certain forms of leukemia, mitochondrial DNA from leukocytes was markedly different from normal. They were open rings or groups of interlocking rings. The incidence of these abnormal forms decreased as a result of chemotherapy.

Bibliography: Gauze G. G. Mitochondrial DNA, M., 1977, bibliogr .; D e P o-bertis E., Novinsky V. and S and e with F. Cell biology, the lane with. from English., M., 1973; Ozernyuk ND Growth and reproduction of mitochondria, M., 1978, bibliogr .; Polikar A. and Bessie M. Elements of cell pathology, lane. with French., M., 1970; RudinD. and Wilkie D. Biogenesis of mitochondria, trans. from English, M., 1970, bibliogr .; Serov V.V. and Spiders V.S. Ultrastructural pathology, M., 1975; With e d of er R. Cytoplasmic genes and organelles, the lane with from English, M., 1975.

T. A. Zaletaeva.

ABOUT COMPLEX SIMPLE LANGUAGE.

This topic is complex and complex, immediately affecting a huge number of biochemical processes occurring in our body. But let's still try to figure out what mitochondria are and how they work.

And so, mitochondria are one of the most important components of a living cell. In simple terms, we can say that this cell power plant... Their activity is based on the oxidation of organic compounds and the generation of an electric potential (energy released during the breakdown of the ATP molecule) for the implementation of muscle contraction.

We all know that the work of our body occurs in strict accordance with the first law of thermodynamics. Energy is not created in our body, but only transforms. The body only chooses the form of energy transformation, without producing it, from chemical to mechanical and thermal. The main source of all energy on planet Earth is the Sun. Coming to us in the form of light, the energy is absorbed by the chlorophyll of plants, where it excites the electron of the hydrogen atom and thus gives the energy of living matter.

We owe our lives to the energy of a small electron.

The work of the mitochondrion consists in the stepwise transfer of the energy of the hydrogen electron between the metal atoms present in the groups of the protein complexes of the respiratory chain (electron transport chain of proteins), where each subsequent complex has a higher affinity for the electron, attracting it than the previous one, as long as the electron not combine with molecular oxygen, which has the highest electron affinity.

Each time an electron is transferred along the circuit, energy is released, which is accumulated in the form of an electrochemical gradient and then realized in the form of muscle contraction and heat release.

A series of oxidative processes in mitochondria that allows the transfer of the energy potential of an electron is called "Intracellular respiration" or often "Breathing chain", since an electron is transferred along a chain from atom to atom until it reaches its final goal of the oxygen atom.

Mitochondria need oxygen to carry energy during oxidation.

Mitochondria consume up to 80% of the oxygen we breathe.

A mitochondrion is a permanent structure of a cell located in its cytoplasm. The mitochondria are usually 0.5 to 1 microns in diameter. In shape, it has a granular structure and can occupy up to 20% of the cell volume. This permanent organic structure of a cell is called an organelle. Organelles also include myofibrils - the contractile units of a muscle cell; and the cell nucleus is also an organelle. In general, any permanent cell structure is an organelle organelle.

He discovered mitochondria and was first described by the German anatomist and histologist Richard Altmann in 1894, and the name of this organelle was given by another German histologist K. Bend in 1897. But only in 1920, again, the German biochemist Otto Wagburg, proved that the processes of cellular respiration are associated with mitochondria.

There is a theory according to which mitochondria appeared as a result of the capture of primitive cells, cells that themselves could not use oxygen to generate energy, protogenotic bacteria that could do it. Precisely because the mitochondrion was previously a separate living organism, it still has its own DNA to this day.

Mitochondria were previously an independent living organism.

In the course of evolution, progenotes have betrayed many of their genes to the nucleus formed, thanks to increased energy efficiency, and ceased to be independent organisms. Mitochondria are present in all cells. Even the sperm contains mitochondria. It is thanks to them that the tail of the sperm is set in motion, which carries out its movement. But there are especially many mitachondria in those places where energy is needed for any life processes. And this, of course, is primarily muscle cells.

In muscle cells, mitochondria can unite into groups of giant branched mitochondria, connected to each other through intermitochondrial contacts, in which they create a coherent working cooperative system... The space in such a zone has an increased electron density. New mitochondria are formed by simply dividing previous organelles. The most "simple" and accessible to all cells mechanism of energy supply is most often called the general concept of glycolysis.

It is the process of successive decomposition of glucose to pyruvic acid. If this process occurs without molecular oxygen or with insufficient presence, then it is called anaerobic glycolysis... In this case, glucose is not broken down to end products, but to lactic and pyruvic acid, which then undergoes further transformations during fermentation. Therefore, the released energy is less, but the speed of obtaining energy is faster. As a result of anaerobic glycolysis from one glucose molecule, the cell receives 2 ATP molecules and 2 lactic acid molecules. This "basic" energy process can take place inside any cell. without the participation of mitochondria.

V presence of molecular oxygen inside mitochondria is carried out aerobic glycolysis within the "respiratory chain". Under aerobic conditions, pyruvic acid is involved in the tricarboxylic acid cycle or the Krebs cycle. As a result of this multi-step process, 36 ATP molecules are formed from one glucose molecule. Comparison of the energy balance of a cell with developed mitochondria and cells where they are not developed shows(with sufficient oxygen) the difference in the completeness of the use of glucose energy inside the cell is almost 20 times!

In humans, skeletal muscle fibers can conditionally divided into three types based on mechanical and metabolic properties: - slow oxidizing; - fast glycolytic; - fast oxidative-glycolytic.

Fast muscle fibers designed for fast and hard work. For their contraction, they mainly use fast energy sources, namely cryatin phosphate and anaerobic glycolysis. The content of mitochondria in these types of fibers is significantly less than in slow muscle fibers.

Slow muscle fibers perform slow contractions, but are able to work for a long time. They use aerobic glycolysis and the synthesis of energy from fats as energy. This gives much more energy than anaerobic glycolysis, but requires more time in replacement, since the chain of glucose degradation is more complex and requires the presence of oxygen, the transport of which to the place of energy conversion also takes time. Slow muscle fibers are called red because of myoglobin, a protein responsible for delivering oxygen to the inside of the fiber. Slow muscle fibers contain a significant amount of mitochondria.

The question arises, how and with the help of what exercises can a branched network of mitochondria be developed in muscle cells? There are various theories and training methods and about them in the material on.

Mitochondria, what are they and what function they perform. Of course, not every person understands why he needs this information. But, if you read this article carefully, your opinion will change.

The internal organization of cells, both animal and plant, can be compared to a commune. What does it mean?

This means that all cells are equal, and they, in turn, perform one specific role. The main role of cells is to create a balanced ensemble.

As for mitochondria, it is a separate structure. Includes many intracellular functions.

The content of the article:
1. General information

general information

The structure was discovered back in the middle of the 19th century. It is worth noting that for a whole 150 years, all scientists believed that mitochondria were capable of performing only one function, namely, to be the energy machine of the cell.

In order to make it a little understandable: the body receives nutritional components, after which a degradation process occurs, which reaches the mitochondria. Then there is an oxidative degradation of all nutrients that have entered the body.

Where do mitochondria live?

Mitochondria are found in the cytoplasm, namely in those areas where there is a need for ATP.

If you look more closely from the point of view of biology, there are many mitochondria in the muscle tissue of the heart. Sperm also contain mitochondria, and their main purpose is to create a protective camouflage. In sperm, mitochondria produce significantly less energy than in the muscle tissue of the heart.

Basic structure of mitochondria

Mitochondria have a rather complex structure. Consists of two membranes, namely an external and an internal one. In addition, there is an intermembrane space.

Inside the mitochondrion itself is the matrix, in other words, this is the internal content. Under the microscope, small outgrowths can be seen on the matrix, these are cristae.

The synthesis of its own protein occurs at the expense of DNA, RNA and, of course, ribosomes.

As for the outer and inner membranes, they perform various functions. It is for this reason that scientists have divided functional abilities into chemical composition.

The membrane does not exceed 10 nm. The outer membrane is a bit like a plasmalemma, so it has a barrier function.

The inner membrane of mitochondria consists of cristae, due to which it forms a multienzymatic system.

Mitochondrial functions

The most basic function of mitochondria is to synthesize ATP (a form of chemical energy). If you carefully study biology, you will notice that the molecule can be formed in two ways.

The first path of education is carried out exclusively as a result of substrate phosphorylation. Second path of education occurs in the process of transferring the residue of phosphoric acid.

Important! Mitochondria use two pathways to synthesize ATP. Why? The fact is that the first path of formation is characteristic of the initial oxidation process, which in turn takes place in the matrix. The second way is the final process of energy education. In this case, the binding of mitochondria to the cristae takes place.

The process of energy education can be conditionally divided into certain stage-by-stage stages. The first two stages occur exclusively in the matrix, as for the remaining stages, they proceed in the mitochondrial cristae.

1. From the cytoplasm to the mitochondria, not only fatty acids begin to flow, but also pyruvic acid salts. It is in the mitochondria that acids are converted into acetyl coenzyme.
2. At the second stage, oxidation occurs - the conenzyme, in medical practice is also called acetyl-CoA. The oxidation process is carried out in the Krebs cycle. At the final stage of the second process, NADH + and two oxygen molecules are formed.
3. At the third stage, electrolytes are transferred along the respiratory chain, directly from NADH to oxygen. Then water is formed.
4. ATP formation.

As you can see, the process of energy formation in the human body is quite serious.

Why are mitochondria needed?

Now you know that mitochondria are cellular organelles that are the main source of energy. To produce energy, organelles need not only oxygen, but also glucose.

With glucose, it is more and more simple, you can replenish its reserves with food, but what about oxygen?

Each person perceives inhalation and exhalation as breathing, this is natural external breathing. The process of breathing itself must be considered from a different point of view.

So, when a person inhales, oxygen begins to flow into the alveoli, after which it enters the bloodstream, then spreads further through the cells and tissues of the body.

Oxygen is made up of cells, which in turn can oxidize nutrients and thereby release energy. Let us fix your attention: the end result of the process is the production of energy in the mitochondria. In medical practice, this process is called cellular respiration.

Now we can draw a small conclusion: the more mitochondria there are, the more our body will receive nutrients.

Is it possible to increase the number of mitochondria on your own?

Yes, you can increase the number of organelles in the body, the main thing is to know how. The easiest way is to do aerobic jogging. At the time of aerobic running, a person breathes freely, thereby supplying a sufficiently large amount of oxygen.

Now let's look at how to increase the penetration of oxygen into the cell. So, in order to increase the partial pressure, directly of carbon dioxide, it is necessary to do exercises for nasal breathing daily. For example: inhaling and exhaling through the nose. Breathing out through the nose is very difficult for a person, but at the same time it is possible to accumulate a lot of carbon dioxide. The second way is to carry out breathing exercises according to the Buteyko method.

The easiest option is, of course, to use special masks or devices.

In addition to exercise and apparatus, it is necessary to adhere to proper nutrition. Include in the diet as many foods as possible that are rich in useful vitamins and macro and micronutrients.

For instance:

1. Meat.
2. Fish.
3. Fruits and vegetables.

In order to increase the level of glucose in the body, which is also actively involved in the synthesis of ATP, include dried fruits and honey in the diet (provided that there is no allergic reaction to the product).

Some doctors advise using vitamins and supplements in pills or capsules. Buy a vitamin complex which includes magnesium, vitamins from group B and C, D-ribose.

Structure and function of mitochondria video

Mitochondria

Mitochondria are rod-shaped or oval-shaped structures (Greek. mitos- a thread, chondros- granule). They are found in all animal cells (excluding mature erythrocytes): in higher plants, in algae and protozoa. They are absent only in bacterial prokaryotes.

These organelles were first discovered and described at the end of the last century by Altman. Later, these structures were called mitochondria. In 1948, Hogeboom pointed out the importance of mitochondria as a center of cellular respiration, and in 1949, Kennedy and Leninger established that a cycle of oxidative phosphorylation occurs in mitochondria. Thus, it was proved that mitochondria serve as a place for generating energy.

Mitochondria are visible in a conventional light microscope with special staining methods. In a phase-contrast microscope and in a "dark field" they can be observed in living cells.

Structure, size, shape mitochondria are highly variable. This primarily depends on the functional state of the cells. For example, it was found that in the motor neurons of flies flying continuously for 2 hours, a huge number of globular mitochondria are manifested, and in flies with glued wings, the number of mitochondria is much smaller and they have a rod-shaped form (L.B. Levinson). In shape, they can be filamentous, rod-shaped, rounded and dumbbell-shaped, even within the same cell.

Mitochondria are localized in the cell, as a rule, either in those areas where energy is expended, or near accumulations of the substrate (for example, lipid droplets), if any.

A strict orientation of mitochondria is found along the sperm flagella, in the striated muscle tissue, where they are located along the myofibrils, in the epithelium of the renal tubules they are localized in the invaginations of the basement membrane, etc.

The number of mitochondria in cells has organ features, for example, in rat liver cells there are from 100 to 2500 mitochondria, and in the cells of the collecting tubules of the kidney - 300, in the spermatozoa of various animal species from 20 to 72, in a giant amoeba Chaos chaos their number reaches 500,000. The sizes of mitochondria range from 1 to 10 microns.

The ultramicroscopic structure of mitochondria is the same, regardless of their shape and size. They are covered with two lipoprotein membranes: outer and inner. The intermembrane space is located between them.

The invaginations of the inner membrane that protrude into the body of the mitochondria are called kristami... The arrangement of cristae in mitochondria can be transverse and longitudinal. Cristae can be simple and branched in shape. Sometimes they form a complex network. In some cells, for example, in the cells of the glomerular zone of the adrenal gland, the cristae look like tubules. The number of cristae is directly proportional to the intensity of oxidative processes in mitochondria. For example, there are several times more of them in the mitochondria of cardiomyocytes than in the mitochondria of hepacites. The space bounded by the inner membrane constitutes the inner mitochondrial chamber. In it, between the cristae, there is a mitochondrial matrix - a relatively electron dense substance.

The proteins of the inner membrane are synthesized by mitoribosomes, and the proteins of the outer membrane are synthesized by cytoribosomes.

"The outer membrane of mitochondria in many respects is similar to the membranes of EPS. It is poor in oxidative enzymes. There are few of them in the membrane space. But the inner membrane and mitochondrial matrix are literally saturated with them. So, in the matrix of mitochondria, enzymes of the Krebs cycle and fatty acid oxidation are concentrated. the membrane contains an electron transport chain, phosphorylation enzymes (the formation of ATP from ADP), and numerous transport systems.

In addition to protein and lipids, the composition of mitochondrial membranes includes RNA, DNA, the latter has genetic specificity, and in its physicochemical properties differs from nuclear DNA.

Electron microscopic studies revealed that the surface of the outer membrane is covered with small spherical elementary particles. The inner membrane and cristae contain similar elementary particles on "legs", the so-called mushroom bodies. They consist of three parts: a spherical head (diameter 90-100 A °), a cylindrical legs, 5 nm long and 3-4 nm wide, a base measuring 4 by 11 nm. The heads of the mushroom bodies are associated with phosphorylation, then the heads were found to contain an enzyme with ATP-like activity.

In the intermembrane space there is a substance with a lower electron density than the matrix. It provides communication between membranes and supplies auxiliary catalysts, coenzymes, for enzymes located in both membranes.

It is now known that the outer membrane of mitochondria is well permeable to substances with low molecular weight, in particular, protein compounds. The inner membrane of mitochondria is selectively permeable. It is practically impermeable to anions (Cl -1, Br -1, SO 4 -2, HCO 3 -1, cations Sn +2, Mg +2, a number of sugars and most amino acids, while Ca 2+, Mn 2+, phosphate , polycarboxylic acids easily penetrate through it. There is evidence of the presence in the inner membrane of several carriers, specific to individual groups of penetrating anions and cations. Active transport of substances through membranes is carried out due to the use of the energy of the ATPase system or the electric potential generated on the membrane as a result of work respiratory chain Even ATP synthesized in mitochondria can be released by a carrier (conjugated transport).

The mitochondrial matrix is ​​represented by a fine-grained electron-dense substance. It contains mitoribosomes, fibrillar structures consisting of DNA molecules and granules with a diameter of more than 200A ◦ formed by salts: Ca 3 (PO 4), Ba 3 (PO 4) 2, Mg 3 (PO 4). It is believed that the granules serve as a reservoir for Ca +2 and Mg +2 ions. Their number increases with a change in the permeability of mitochondrial membranes.

The presence of DNA in mitochondria ensures the participation of mitochondria in the synthesis of RNA and specific proteins, and also indicates the existence of cytoplasmic inheritance. Each mitochondrion contains, depending on the size, one or more DNA molecules (from 2 to 10). The molecular weight of mitochondrial DNA is about (30-40) * 10 6 in protozoa, yeast, fungi. Higher animals have about (9–10) * 10 6.

Its length in yeast is approximately 5 microns, in plants - 30 microns. The amount of genetic information contained in mitochondrial DNA is small: it consists of 15-75 thousand base pairs, which can encode an average of 25-125 protein chains with a molecular weight of about 40,000.

Mitochondrial DNA differs from nuclear DNA in a number of features: a higher synthesis rate (5-7 times), it is more resistant to the action of DNase, is a two-ring molecule, contains more guanine and cytosine, denatures at a higher temperature and is easier to recover. However, not all mitochondrial proteins are synthesized by the mitochondrial system. Thus, the synthesis of cytochrome C and other enzymes is provided by the information contained in the nucleus. In the matrix of mitochondria, vitamins A, B2, B 12, K, E, as well as glycogen are localized.

Mitochondrial function consists in the formation of energy necessary for the vital activity of cells. Various compounds can serve as a source of energy in a cell: proteins, fats, carbohydrates. However, the only substrate that is immediately involved in energy processes is glucose.

Biological processes, as a result of which energy is generated in mitochondria, can be divided into 3 groups: Group I - oxidative reactions, which include two phases: anaerobic (glycolysis) and aerobic. Group II - dephosphorylation, cleavage of ATP and release of energy. Group III - phosphorylation associated with the oxidation process.

The process of glucose oxidation initially occurs without the participation of oxygen (anaerobic or glycolytic) to pyruvic or lactic acid.

However, only a small amount of energy is released. Subsequently, these acids are involved in oxidation processes that take place with the participation of oxygen, that is, they are aerobic. As a result of the oxidation process of pyruvic and lactic acid, called the Krebs cycle, carbon dioxide, water and a large amount of energy are formed.

The resulting energy is not released in the form of heat, which would lead to overheating of cells and the death of the whole organism, but is accumulated in a form convenient for storage and transport in the form of adenosine triphosphoric acid (ATP). The synthesis of ATP comes from ADP and phosphoric acid and is therefore called phosphorylation.

In healthy cells, phosphorylation is associated with oxidation. In diseases, the conjugation can be uncoupled, so the substrate is oxidized, but phosphorylation does not occur, and the oxidation turns into heat, and the ATP content in the cells decreases. As a result, the temperature rises and the functional activity of the cells decreases.

So, the main function of mitochondria is to generate practically all the energy of the cell and the synthesis of components necessary for the activity of the organoid itself, enzymes of the "respiratory ensemble", phospholipids and proteins occurs.

Another aspect of the activity of mitochondria is their participation in specific syntheses, for example, in the synthesis of steroid hormones and individual lipids. In oocytes of different animals, accumulations of yolk are formed in mitochondria, while they lose their main system. Spent mitochondria can also accumulate excretion products.

In some cases (liver, kidneys) mitochondria are able to accumulate harmful substances and poisons that enter the cell, isolating them from the main cytoplasm and partially blocking the harmful effects of these substances. Thus, mitochondria are able to take on the functions of other organelles of the cell when it is required to fully support a particular process under normal or extreme conditions.

Mitochondrial biogenesis. Mitochondria are renewable structures with a rather short life cycle (in rat liver cells, for example, the half-life of mitochondria is about 10 days). Mitochondria are formed as a result of the growth and division of the anterior mitochondria. Their division can occur in three ways: constriction, budding of small areas and the emergence of daughter mitochondria inside the mother. The division (reproduction) of mitochondria is preceded by the reproduction of its own genetic system - mitochondrial DNA.

So, according to the views of most researchers, the formation of mitochondria occurs mainly through their self-reproduction de novo.

In the cells of any living organism there are special organelles that move, function, merge with each other and multiply. They are called mitochondria or chondriosomes. Similar structures are found both in the cells of protozoa and in the cells of plants and animals. For a long time, during the study, the functions of the mitochondria were also studied, because it was of particular interest.

Indeed, at the cellular level, mitochondria perform a specific and very important function - they generate energy in the form of adenosine triphosphate. It is a key nucleotide in the metabolism of organisms and its conversion into energy. ATP acts as a universal source of energy required for any biochemical processes in the body. This is the main function of mitochondria - maintain vital activity at the cellular level due to the formation of ATP.

For a long time, the processes taking place in cells were of particular interest to scientists, because they helped to better understand the structure and capabilities of the organism. The cognition process always takes a long time. So Karl Lohmann discovered adenosine triphosphate in 1929, and Fritz Lipmann in 1941 figured out that it is the main supplier of energy to cells.

Mitochondrial structure

The appearance is as interesting as the function of the mitochondria. The sizes and shapes of these organelles are variable and can be different depending on the types of living beings. If we describe the average values, then the granular and filamentous mitochondria, consisting of two membranes, has dimensions of the order of 0.5 micromillimeters in thickness, and the length can reach 60 micromillimeters.

As mentioned above, scientists have been trying for a long time to understand the question of what is the structure and function of mitochondria. The main difficulties were with insufficient development of equipment, because it is almost impossible to study the microworld in other ways.

Mitochondria contain more than plant cells, because energy conversion is more important for animals from an evolutionary point of view. However, it is rather difficult to explain such processes, but in plant cells such functions are performed mainly by chloroplasts.

In cells, mitochondria can be located in a variety of places where there is a need for ATP. We can say that mitochondria have a fairly universal structure, so they can appear in different places.

Mitochondria functions

The main function of mitochondria - synthesis of ATP molecules. This is a kind of energy station of the cell, which, due to the oxidation of various, releases energy due to their decay.

The main source of energy, i.e. the compound used for breakdown is It, in turn, the body receives from proteins, carbohydrates and fats. There are two ways of generating energy, with mitochondria using both. The first of these is associated with the oxidation of pyruvate in the matrix. The second is already associated with the cristae of the organelles and directly completes the process of energy production.

In general, this mechanism is quite complex and takes place in several stages. Long lines are built, the only purpose of which is to provide energy to other cellular processes. Maintaining the body at the cellular level allows you to maintain its vital functions as a whole. That is why scientists have been trying for a long time to figure out exactly how these processes occur. Over time, many issues were resolved, especially the study of DNA and the structure of the remaining small cells of the microworld helped in this. Without this, it would hardly be possible to imagine the development of this science as a whole, as well as the study of the human body and highly developed animals.