The body is constantly associated with the exchange of energy. Energy metabolism reactions occur constantly, even when we are sleeping. After complex chemical changes, food substances are converted from high molecular weight to simple ones, which is accompanied by the release of energy. This is all energy exchange.

The body's energy demands while running are very high. For example, 2.5-3 hours of running consumes about 2,600 calories (this is a marathon distance), which significantly exceeds the energy consumption of a person leading a sedentary lifestyle per day. During the race, the body draws energy from the reserves of muscle glycogen and fats.

Muscle glycogen, a complex chain of glucose molecules, accumulates in active muscle groups. Aerobic glycolysis and two other chemical processes convert glycogen to adenosine triphosphate (ATP).

The ATP molecule is the main source of energy in our body. Maintaining energy balance and energy metabolism occurs at the level of the cell. The speed and endurance of the runner depends on the respiration of the cage. Therefore, in order to achieve the highest results, it is necessary to provide the cell with oxygen for the entire distance. This is what training is for.

Energy in the human body. Stages of energy metabolism.

We always receive and spend energy. In the form of food, we get the main nutrients, or ready-made organic matter, this proteins, fats and carbohydrates. The first stage is digestion, there is no release of energy that our body can store.

The digestive process is not aimed at obtaining energy, but at breaking down large molecules into small ones. Ideally, everything should be split into monomers. Carbohydrates are broken down to glucose, fructose and galactose. Fats - to glycerol and fatty acids, proteins to amino acids.

Breathing cells

Besides digestion, there is a second part or stage. This is breathing. We breathe and pump air into the lungs, but this is not the main part of breathing. Breathing is when our cells use oxygen to burn nutrients down to water and carbon dioxide for energy. This is the final stage of obtaining energy that takes place in each of our cells.

The main source of human nutrition is carbohydrates accumulated in the muscles in the form of glycogen; glycogen is usually enough for 40-45 minutes of running. After this time, the body must switch to another source of energy. These are fats. Fat is an alternative energy to glycogen.

alternative energy- this means the need to choose one of two sources of energy or fat or glycogen. Our body can receive energy from only one source.

Long-distance running differs from short-distance running in that the stayer's body inevitably switches to using muscle fat as an additional source of energy.

Fatty acids are not the best substitute for carbohydrates, as their release and use takes much more energy and time. But if glycogen is over, then the body has no choice but to use fats, thus obtaining the necessary energy. It turns out that fats are always a reserve option for the body.

Note that the fats used when running are fats found in muscle fibers, not fatty layers that cover the body.

When burning or splitting any organic matter, production wastes are obtained, this is carbon dioxide and water. Our organics are proteins, fats and carbohydrates. Carbon dioxide is exhaled with air, and water is used by the body or excreted in sweat or urine.

Digesting nutrients, our body loses some of its energy in the form of heat. So the engine in the car heats up and loses energy into the void, and the runner's muscles spend a huge amount of energy. converting chemical energy into mechanical energy. Moreover, the efficiency is about 50%, that is, half of the energy goes into the air in the form of heat.

The main stages of energy metabolism can be distinguished:

We eat in order to get nutrients, break them down, then with the help of oxygen, the oxidation process takes place, as a result we get energy. Part of the energy always leaves in the form of heat, and we store part of it. Energy is stored in the form of a chemical compound called ATP.

What is ATP?

ATP is adenosine triphosphate, which is of great importance in the metabolism of energy and substances in organisms. ATP is a universal source of energy for all biochemical processes in living systems.

In the body, ATP is one of the most frequently renewed substances, so in humans, the lifespan of one ATP molecule is less than a minute. During the day, one ATP molecule goes through an average of 2000-3000 resynthesis cycles. The human body synthesizes about 40 kg of ATP per day, but contains about 250 g at any given moment, that is, there is practically no supply of ATP in the body, and for normal life it is necessary to constantly synthesize new ATP molecules.

Conclusion: Our body can store energy for itself in the form of a chemical compound. This is ATP.

ATP consists of a nitrogenous base adenine, ribose and triphosphate - phosphoric acid residues.

It takes a lot of energy to create ATP, but when it is destroyed, this energy can be returned. Our body, breaking down nutrients, creates an ATP molecule, and then, when it needs energy, it breaks down the ATP molecule or cleaves the bonds of the molecule. By cleaving off one of the phosphoric acid residues, you can get about -40 kJ. ⁄ mol.

This always happens because we constantly need energy, especially while running. The sources of energy input into the body can be different (meat, fruits, vegetables, etc.) . The internal source of energy is the same - it is ATP. The life of a molecule is less than a minute. therefore, the body constantly breaks down and reproduces ATP.

Splitting energy. Cell energy

Dissimilation

We get the main energy from glucose in the form of an ATP molecule. Since we need energy all the time, these molecules will enter the body where it is necessary to give energy.

ATP gives up energy, and at the same time is split to ADP - adenosine diphosphate. ADP is the same ATP molecule, only without one phosphoric acid residue. Di means two. Glucose, splitting, gives up energy, which is taken by ADP and restores its phosphorus balance, turning into ATP, which is again ready to spend energy. This happens all the time.

This process is called - dissimilation. (destruction) In this case, in order to obtain energy, it is necessary to destroy the ATP molecule.

Assimilation

But there is also another process. You can build your own substances with the expenditure of energy. This process is called - assimilation... Create larger substances from smaller ones. Production of our own proteins, nucleic acids, fats and carbohydrates.

For example_ you ate a piece of meat, Meat is a protein that must be broken down into amino acids, from these amino acids their own proteins will be collected or synthesized, which will become your muscles. This will take some of the energy.

Getting energy. What is glycolysis?

One of the processes of obtaining energy for all living organisms is glycolysis. Glycolysis can be found in the cytoplasm of any of our cells. The name "glycolysis" comes from the Greek. - sweet and Greek. - dissolution.

Glycolysis is an enzymatic process of sequential breakdown of glucose in cells, accompanied by the synthesis of ATP. These are 13 enzymatic reactions. Glycolysis at aerobic conditions leads to the formation of pyruvic acid (pyruvate).

Glycolysis in anaerobic conditions leads to the formation of lactic acid (lactate). Glycolysis is the main pathway for glucose catabolism in animals.

Glycolysis is one of the oldest metabolic processes known in almost all living organisms. Presumably, glycolysis appeared more than 3.5 billion years ago in primary prokaryotes... (Prokaryotes are organisms in whose cells there is no formalized nucleus. Its functions are performed by a nucleotide (that is, "like a nucleus"); unlike a nucleus, a nucleotide does not have its own shell).

Anaerobic glycolysis

Anaerobic glycolysis is a way to get energy from a glucose molecule without using oxygen. The process of glycolysis (breakdown) is the process of glucose oxidation, in which two molecules are formed from one glucose molecule pyruvic acid.

The glucose molecule splits into two halves that can be called- pyruvate, this is the same as pyruvic acid. Each half of pyruvate can restore an ATP molecule. It turns out that one glucose molecule, when broken down, can restore two ATP molecules.

With a long run or when running in anaerobic mode, after a while it becomes difficult to breathe, the muscles of the legs get tired, the legs become heavy, they, like you, stop receiving enough oxygen.

Because the process of obtaining energy in the muscles ends with glycolysis. Therefore, the muscles start to ache and refuse to work due to lack of energy. Formed lactic acid or lactate. It turns out that the faster the athlete runs, the faster he produces lactate. Blood lactate levels are closely related to exercise intensity.

Aerobic glycolysis

By itself, glycolysis is a completely anaerobic process, that is, it does not require the presence of oxygen for the reactions to proceed. But you must admit that obtaining two ATP molecules during glycolysis is very small.

Therefore, the body has an alternative option for obtaining energy from glucose. But already with the participation of oxygen. This is oxygen breathing. which each of us possesses, or aerobic glycolysis... Aerobic glycolysis is able to quickly restore muscle ATP stores.

During dynamic activities such as running, swimming, etc., aerobic glycolysis occurs. that is, if you run and do not choke, but calmly talk with a running comrade next to you, then we can say that you are running in an aerobic mode.

Respiration or aerobic glycolysis occurs in mitochondria under the influence of special enzymes and requires oxygen consumption, and, accordingly, time for its delivery.

Oxidation occurs in several stages, first there is glycolysis, but the two pyruvate molecules formed during the intermediate stage of this reaction are not converted into lactic acid molecules, but penetrate into mitochondria, where they are oxidized in the Krebs cycle to carbon dioxide CO2 and water H2O and provide energy for the production another 36 ATP molecules.

Mitochondria these are special organelles that are in the cell, therefore there is oneSome concept, like cellular respiration. Such respiration occurs in all organisms that need oxygen, including you and me.

Glycolysis is a catabolic pathway of exceptional importance. It provides energy for cellular reactions, including protein synthesis. Glycolysis intermediates are used in the synthesis of fats. Pyruvate can also be used to synthesize alanine, aspartate, and other compounds. Thanks to glycolysis, mitochondrial performance and oxygen availability do not limit muscle power during short-term extreme loads. Aerobic oxidation is 20 times more efficient than anaerobic glycolysis.

What is mitochondria?

Mitochondria (from the Greek μίτος - thread and χόνδρος - grain, grain) is a two-membrane spherical or ellipsoidal organoid with a diameter of usually about 1 micrometer. Energy station of the cell; the main function is the oxidation of organic compounds and the use of the energy released during their decay to generate an electric potential, ATP synthesis and thermogenesis.

The number of mitochondria in a cell is not constant. They are especially abundant in cells in which the need for oxygen is high. Depending on in which parts of the cell at any given moment there is an increased consumption of energy, mitochondria in the cell are able to move through the cytoplasm to the zones of greatest energy consumption.

Mitochondrial functions

One of the main functions of mitochondria is the synthesis of ATP, a universal form of chemical energy in any living cell. Look, the entrance is two molecules of pyruvate, and the exit is a huge amount of "many things." This "a lot of things" is called the "Krebs Cycle". By the way, Hans Krebs received the Nobel Prize for opening this cycle.

We can say that this is the tricarboxylic acid cycle. In this cycle, many substances are sequentially converted into each other. In general, as you understand, this thing is very important and understandable for biochemists. In other words, it is a key step in the respiration of all oxygen-using cells.

As a result, the output we get is carbon dioxide, water and 36 ATP molecules. Let me remind you that glycolysis (without the participation of oxygen) produced only two ATP molecules per glucose molecule. Therefore, when our muscles begin to work without oxygen, they greatly lose efficiency. That is why all workouts are aimed at ensuring that the muscles can work on oxygen for as long as possible.

Mitochondrion structure

The mitochondrion has two membranes: outer and inner. The main function of the outer membrane is to separate the organoid from the cytoplasm of the cell. It consists of a bilipid layer and proteins that permeate it, through which the transport of molecules and ions necessary for mitochondria to work is carried out.

While the outer membrane is smooth, the inner membrane forms numerous folds -crista, which significantly increase its area. The inner membrane mostly consists of proteins, among which there are respiratory chain enzymes, transport proteins and large ATP - synthetase complexes. It is in this place that ATP synthesis occurs. Between the outer and inner membranes there is an intermembrane space with its inherent enzymes.
The inner space of mitochondria is called matrix... Here are the enzyme systems for the oxidation of fatty acids and pyruvate, enzymes of the Krebs cycle, as well as the hereditary material of mitochondria - DNA, RNA and protein synthesizing apparatus.

The mitochondrion is the only source of energy for cells. Located in the cytoplasm of each cell, mitochondria are comparable to "batteries" that produce, store and distribute the energy necessary for the cell.
Human cells contain an average of 1,500 mitochondria. They are especially abundant in cells with intensive metabolism (for example, in muscles or liver).
Mitochondria are mobile and move in the cytoplasm depending on the needs of the cell. Due to the presence of their own DNA, they multiply and self-destruct regardless of cell division.
Cells cannot function without mitochondria; life is impossible without them.

Ecology of consumption. Science and technology: One of the main problems of alternative energy is the uneven supply of it from renewable sources. Let's consider how it is possible to accumulate types of energy (although for practical use, we will then need to convert the accumulated energy either into electricity or into heat).

One of the main problems of alternative energy is the uneven supply of it from renewable sources. The sun shines only during the day and in cloudless weather, the wind either blows or dies down. And the demand for electricity is not constant, for example, it takes less for lighting during the day, and more in the evening. And people like it when cities and villages are flooded with illuminations at night. Well, or at least just the streets are lit. So the task arises - to save the received energy for some time, in order to use it when the need for it is maximum, and the receipt is not enough.

There are 6 main types of energy: gravitational, mechanical, thermal, chemical, electromagnetic and nuclear. By now, mankind has learned to create artificial batteries for the energy of the first five types (well, except that the available reserves of nuclear fuel are of artificial origin). So we will consider how it is possible to accumulate and store each of these types of energy (although for practical use we will then need to convert the accumulated energy either into electricity or into heat).

Accumulators of gravitational energy

In accumulators of this type, at the stage of energy accumulation, the load rises up, accumulating potential energy, and at the right moment it drops back, returning this energy usefully. The use of solids or liquids as a load brings its own characteristics to the design of each type. An intermediate position between them is occupied by the use of bulk substances (sand, lead shot, small steel balls, etc.).

Gravitational Solid State Energy Storage

The essence of gravitational mechanical storage is that a certain load rises to a height and at the right time is released, forcing the generator axis to rotate along the way. An example of the implementation of this method of energy storage is a device proposed by the California-based company Advanced Rail Energy Storage (ARES). The idea is simple: at a time when solar panels and windmills produce a lot of energy, special heavy carriages are driven up the mountain with the help of electric motors. At night and in the evening, when there are not enough energy sources to supply consumers, the cars go down, and the motors, which work as generators, return the stored energy back to the grid.

Almost all mechanical drives of this class have a very simple design, and therefore high reliability and long service life. The storage time of once stored energy is practically unlimited, unless the load and structural elements crumble over time from old age or corrosion.

The energy stored in lifting solids can be released in a very short time. A limitation on the power received from such devices is imposed only by the acceleration of gravity, which determines the maximum rate of increase in the speed of the falling weight.

Unfortunately, the specific energy consumption of such devices is low and is determined by the classical formula E = m · g · h. Thus, in order to store energy for heating 1 liter of water from 20 ° C to 100 ° C, it is necessary to lift a ton of cargo at least 35 meters (or 10 tons per 3.5 meters). Therefore, when it becomes necessary to store more energy, this immediately leads to the need to create bulky and, as an inevitable consequence, expensive structures.

The disadvantage of such systems is that the path along which the cargo moves must be free and fairly straight, and it is also necessary to exclude the possibility of accidental falling into this area of ​​things, people and animals.

Gravitational fluid storage

Unlike solid weights, when using liquids, there is no need to create straight shafts with a large section for the entire lifting height - the liquid moves perfectly along curved pipes, the section of which should only be sufficient for the maximum design flow to pass through them. Therefore, the upper and lower reservoirs do not have to be located one under the other, but can be separated by a sufficiently large distance.

Pumped storage power plants (PSPP) belong to this class.

There are also smaller-scale hydraulic accumulators of gravitational energy. First, we pump 10 tons of water from an underground reservoir (well) into a container on the tower. Then the water from the tank under the action of gravity flows back into the tank, rotating a turbine with an electric generator. The service life of such a drive can be 20 years or more. Advantages: when using a wind turbine, the latter can directly drive a water pump; water from a tank on the tower can be used for other needs.

Unfortunately, hydraulic systems are more difficult to maintain in proper technical condition than solid-state ones - first of all, this concerns the tightness of tanks and pipelines and the serviceability of shut-off and pumping equipment. And one more important condition - at the moments of accumulation and use of energy, the working fluid (at least, a fairly large part of it) must be in a liquid state of aggregation, and not be in the form of ice or steam. But sometimes in such storage devices it is possible to obtain additional free energy, say, when replenishing the upper reservoir with melt or rainwater.

Mechanical energy storage

Mechanical energy manifests itself during the interaction, movement of individual bodies or their particles. It includes the kinetic energy of movement or rotation of the body, the energy of deformation during bending, stretching, twisting, compression of elastic bodies (springs).

Gyroscopic energy storage

In gyroscopic storage devices, energy is stored in the form of kinetic energy of a rapidly rotating flywheel. The specific energy stored for each kilogram of the flywheel weight is much higher than what can be stored in a kilogram of static load, even when it is lifted to a great height, and the latest high-tech developments promise a density of stored energy comparable to the stock of chemical energy per unit mass of the most efficient types of chemical fuel.

Another huge plus of the flywheel is the ability to quickly return or receive very high power, limited only by the tensile strength of materials in the case of mechanical transmission or the "throughput" of electric, pneumatic or hydraulic transmissions.

Unfortunately, flywheels are sensitive to shocks and twists in planes other than the plane of rotation, as this creates huge gyroscopic loads that tend to bend the axis. In addition, the storage time of the energy stored in the flywheel is relatively short and for conventional designs typically ranges from a few seconds to several hours. Further, the energy losses due to friction become too noticeable ... However, modern technologies make it possible to dramatically increase the storage time - up to several months.

Finally, one more unpleasant moment - the energy stored by the flywheel directly depends on its rotation speed, therefore, as energy is accumulated or released, the rotation speed changes all the time. At the same time, the load very often requires a stable rotation speed, not exceeding several thousand revolutions per minute. For this reason, purely mechanical systems for transmitting power to and from the flywheel can be too complex to manufacture. Sometimes an electromechanical transmission can simplify the situation using a motor-generator located on the same shaft with a flywheel or a rigid gearbox associated with it. But then energy losses for heating wires and windings are inevitable, which can be much higher than losses for friction and slippage in good variators.

Particularly promising are the so-called super flywheels, consisting of turns of steel tape, wire or high-strength synthetic fiber. The winding can be dense, or it can have a specially left empty space. In the latter case, as the flywheel unwinds, the tape turns move from its center to the periphery of rotation, changing the moment of inertia of the flywheel, and if the tape is spring, then it stores part of the energy in the elastic deformation energy of the spring. As a result, in such flywheels, the rotation speed is not so directly related to the stored energy and is much more stable than in the simplest solid structures, and their energy consumption is noticeably higher.

In addition to their greater energy intensity, they are safer in the event of various accidents, since, unlike fragments of a large monolithic flywheel, in their energy and destructive force comparable to cannonballs, fragments of a spring have a much lower "lethality" and usually quite effectively slow down a burst flywheel for the account of friction against the walls of the body. For the same reason, modern solid flywheels, designed to operate in modes close to the redistribution of material strength, are often made not monolithic, but woven from ropes or fibers impregnated with a binder.

Modern designs with a vacuum rotation chamber and a magnetic suspension of a super flywheel made of Kevlar fiber provide a stored energy density of more than 5 MJ / kg, and they can store kinetic energy for weeks or months. According to optimistic estimates, the use of a super-strong "supercarbon" fiber for winding will increase the rotation speed and specific density of the stored energy many times more - up to 2-3 GJ / kg (they promise that one spin of such a flywheel weighing 100-150 kg will be enough for a run in a million kilometers or more, i.e. for virtually the entire lifetime of the car!). However, the cost of this fiber is still many times higher than the cost of gold, so even Arab sheikhs cannot afford such machines yet ... You can read more about flywheel drives in the book of Nurbey Gulia.

Gyroresonant energy storage

These accumulators are the same flywheel, but made of elastic material (for example, rubber). As a result, it has fundamentally new properties. As the speed increases on such a flywheel, "outgrowths" - "petals" begin to form - first it turns into an ellipse, then into a "flower" with three, four or more "petals" ... practically does not change, and energy is stored in the resonant wave of elastic deformation of the flywheel material, which forms these "petals".

In the late 1970s and early 1980s, N.Z. Garmash was engaged in such designs in Donetsk. The results he obtained are impressive - according to his estimates, at a flywheel operating speed of only 7-8 thousand rpm, the stored energy was sufficient for the car to travel 1,500 km versus 30 km with a conventional flywheel of the same size. Unfortunately, more recent information about this type of drive is unknown.

Mechanical accumulators using elastic forces

This class of devices has a very high specific energy storage capacity. If it is necessary to observe small dimensions (several centimeters), its energy consumption is the highest among mechanical storage devices. If the requirements for weight and size characteristics are not so stringent, then large ultra-high-speed flywheels surpass it in energy intensity, but they are much more sensitive to external factors and have a much shorter energy storage time.

Spring mechanical storage

Compression and expansion of the spring is capable of providing a very high flow rate and energy supply per unit of time - perhaps the greatest mechanical power among all types of energy storage devices. As in flywheels, it is limited only by the strength of the materials, but the springs usually implement the working translational movement directly, and in flywheels one cannot do without a rather complex transmission (it is no coincidence that either mechanical mainsprings or gas canisters are used in pneumatic weapons, which, by their own in fact, they are pre-charged air springs; before the advent of firearms, spring weapons were also used for combat at a distance - bows and crossbows, which, long before the new era, completely supplanted the sling with its kinetic accumulation of energy in professional troops).

The stored energy in a compressed spring can be stored for many years. However, it should be borne in mind that under the influence of constant deformation, any material accumulates fatigue over time, and the crystal lattice of the spring metal slowly changes, and the greater the internal stresses and the higher the ambient temperature, the sooner and to a greater extent this will happen. Therefore, after several decades, the compressed spring, without changing outwardly, may be "discharged" in whole or in part. However, high-quality steel springs, if they are not exposed to overheating or hypothermia, are capable of working for centuries without any visible loss of capacity. For example, an antique mechanical wall clock from one complete factory still runs for two weeks - as it did more than half a century ago when it was made.

If it is necessary to gradually and uniformly "charge" and "discharge" the spring, the mechanism providing this can be very complex and capricious (look into the same mechanical watch - in fact, many gears and other parts serve this very purpose). Electromechanical transmission can simplify the situation, but it usually imposes significant restrictions on the instantaneous power of such a device, and when working with low powers (several hundred watts or less), its efficiency is too low. A separate task is the accumulation of maximum energy in a minimum volume, since this generates mechanical stresses close to the ultimate strength of the materials used, which requires particularly careful calculations and impeccable workmanship.

Speaking here about springs, one must bear in mind not only metal, but also other elastic solid elements. The most common among them are rubber bands. By the way, in terms of energy stored per unit of mass, rubber exceeds steel dozens of times, but it also serves about the same times less, and, unlike steel, it loses its properties after a few years even without active use and with ideal external conditions - due to the relatively rapid chemical aging and degradation of the material.

Mechanical gas storage

In this class of devices, energy is accumulated due to the elasticity of the compressed gas. When there is an excess of energy, the compressor pumps gas into the cylinder. When the stored energy needs to be used, compressed gas is fed into a turbine, which directly performs the necessary mechanical work or rotates an electric generator. Instead of a turbine, you can use a piston engine, which is more efficient at low power (by the way, there are also reversible piston engine-compressors).

Almost every modern industrial compressor is equipped with a similar accumulator - a receiver. True, the pressure there rarely exceeds 10 atm, and therefore the energy reserve in such a receiver is not very large, but this also usually allows several times to increase the installation resource and save energy.

Gas compressed to a pressure of tens and hundreds of atmospheres can provide a sufficiently high specific density of stored energy for an almost unlimited time (months, years, and with a high quality of the receiver and shut-off valves - tens of years, it is not for nothing that pneumatic weapons using canisters with compressed gas, has become so widespread). However, the compressor with a turbine or a reciprocating engine included in the installation are rather complicated, capricious devices and have a very limited resource.

A promising technology for creating energy reserves is to compress air using available energy at a time when there is no immediate need for the latter. The compressed air is cooled and stored at a pressure of 60-70 atmospheres. If it is necessary to consume the stored energy, the air is extracted from the storage device, heats up, and then enters a special gas turbine, where the energy of the compressed and heated air rotates the turbine stages, the shaft of which is connected to an electric generator that supplies electricity to the power system.

For the storage of compressed air, it is proposed, for example, to use suitable mines or specially created underground tanks in salt formations. The concept is not new, storage of compressed air in an underground cave was patented back in 1948, and the first compressed air energy storage (CAES) plant with a capacity of 290 MW has been operating at the Huntorf power plant in Germany since 1978. During the compression stage of air, a large amount of energy is lost as heat. This lost energy must be compensated for by compressed air before the expansion stage in the gas turbine, for this, hydrocarbon fuel is used, with the help of which the air temperature is raised. This means that the installations have far from one hundred percent efficiency.

There is a promising avenue for improving the effectiveness of CAES. It consists in retaining and storing the heat generated during the operation of the compressor during the compression and cooling of the air, with its subsequent reuse when the cold air is reheated (so-called recuperation). However, this CAES option has significant technical difficulties, especially in the direction of creating a long-term heat preservation system. If these problems are addressed, AA-CAES (Advanced Adiabatic-CAES) could pave the way for large-scale energy storage systems, a problem that has been raised by researchers around the world.

Members of the Canadian startup Hydrostor have proposed another unusual solution - to pump energy into underwater bubbles.

Thermal energy storage

In our climatic conditions, a very significant (often the main) part of the energy consumed is spent on heating. Therefore, it would be very convenient to accumulate heat directly in the storage device and then receive it back. Unfortunately, in most cases, the density of stored energy is very low, and the terms of its conservation are very limited.

There are heat accumulators with solid or melting heat storage material; liquid; steam; thermochemical; with an electric heating element. Heat accumulators can be connected to a system with a solid fuel boiler, a solar system or a combined system.

Energy storage due to heat capacity

In storage devices of this type, heat is accumulated due to the heat capacity of a substance serving as a working fluid. A classic example of a heat accumulator is the Russian stove. It was heated once a day, and then it heated the house for 24 hours. Nowadays, a heat accumulator most often means tanks for storing hot water, sheathed with a material with high thermal insulation properties.

There are also heat accumulators based on solid heat carriers, for example, in ceramic bricks.

Different substances have different heat capacities. For most, it is in the range from 0.1 to 2 kJ / (kg · K). Water has an abnormally high heat capacity - its heat capacity in the liquid phase is approximately 4.2 kJ / (kg K). Only very exotic lithium has a higher heat capacity - 4.4 kJ / (kg · K).

However, in addition to the specific heat capacity (by mass), it is necessary to take into account the volumetric heat capacity, which makes it possible to determine how much heat is needed to change the temperature of the same volume of different substances by the same amount. It is calculated from the usual specific (mass) heat capacity by multiplying it by the specific density of the corresponding substance. The volumetric heat capacity should be guided by when the volume of the heat accumulator is more important than its weight.

For example, the specific heat capacity of steel is only 0.46 kJ / (kg K), but the density is 7800 kg / cubic meter, and, say, for polypropylene - 1.9 kJ / (kg is only 900 kg / m3. Therefore, with the same volume, steel will be able to store 2.1 times more heat than polypropylene, although it will be almost 9 times heavier. However, due to the abnormally high heat capacity of water, no material can surpass it in terms of volumetric heat capacity. However, the volumetric heat capacity of iron and its alloys (steel, cast iron) differs from water by less than 20% - in one cubic meter they can store more than 3.5 MJ of heat for each degree of temperature change, the volumetric heat capacity of copper is slightly less - 3.48 MJ /(cube.m K). The heat capacity of air under normal conditions is about 1 kJ / kg, or 1.3 kJ / cubic meter, so to heat a cubic meter of air by 1 °, it is enough to cool slightly less than 1/3 liter of water by the same degree (naturally, hotter than air ).

Due to the simplicity of the device (which could be simpler than a stationary solid piece of solid or a closed reservoir with a liquid heat carrier?), Such energy storage devices have an almost unlimited number of energy storage-release cycles and a very long service life - for heat transfer fluids until the liquid dries out or until the reservoir is damaged from corrosion or other reasons, for solid-state there are no these restrictions. But the storage time is very limited and, as a rule, ranges from several hours to several days - for a longer period, ordinary thermal insulation is no longer capable of retaining heat, and the specific density of the stored energy is not high.

Finally, one more circumstance should be emphasized - for effective operation, not only the heat capacity is important, but also the thermal conductivity of the heat accumulator substance. With a high thermal conductivity, even to fairly rapid changes in external conditions, the heat accumulator will react with its entire mass, and therefore all the stored energy - that is, as efficiently as possible.

In the case of poor thermal conductivity, only the surface part of the heat accumulator will have time to react, and short-term changes in external conditions simply will not have time to reach the deep layers, and a significant part of the substance of such a heat accumulator will actually be excluded from work.

Polypropylene, mentioned in the example considered just above, has a thermal conductivity almost 200 times less than steel, and therefore, despite the sufficiently large specific heat, it cannot be an effective heat accumulator. However, technically, the problem is easily solved by organizing special channels for circulating the coolant inside the heat accumulator, but it is obvious that such a solution significantly complicates the design, reduces its reliability and energy consumption, and will certainly require periodic maintenance, which is unlikely to be needed for a monolithic piece of material.

Strange as it may seem, sometimes it is necessary to accumulate and store not heat, but cold. For more than a decade, companies have been operating in the US that offer ice-based "batteries" for installation in air conditioners. At night, when there is a surplus of electricity and it is sold at reduced rates, the air conditioner freezes the water, that is, it switches to refrigerator mode. In the daytime, it consumes several times less energy, working as a fan. The energy-hungry compressor is turned off for this time. ...

Energy accumulation during a change in the phase state of matter

If you look closely at the thermal parameters of various substances, you can see that when the state of aggregation changes (melting-hardening, evaporation-condensation), there is a significant absorption or release of energy. For most substances, the thermal energy of such transformations is enough to change the temperature of the same amount of the same substance by many tens, or even hundreds of degrees in those temperature ranges where its state of aggregation does not change. But, as you know, until the state of aggregation of the entire volume of a substance becomes the same, its temperature is practically constant! Therefore, it would be very tempting to accumulate energy due to a change in the state of aggregation - a lot of energy accumulates, and the temperature changes little, so that as a result, it is not necessary to solve the problems associated with heating to high temperatures, and at the same time, you can get a good capacity of such a heat accumulator.

Melting and crystallization

Unfortunately, at present, there are practically no cheap, safe and decomposition-resistant substances with high phase transition energy, the melting point of which would lie in the most relevant range - approximately from + 20 ° С to + 50 ° С (maximum + 70 ° С - this is still a relatively safe and easily attainable temperature). As a rule, complex organic compounds melt in this temperature range, which are by no means beneficial to health and are often rapidly oxidized in air.

Perhaps the most suitable substances are paraffins, the melting point of most of which, depending on the type, lies in the range 40 ... 65 ° C (although there are also "liquid" paraffins with a melting point of 27 ° C or less, as well as natural ozokerite, related to paraffins, the melting point of which lies in the range of 58..100 ° С). Both paraffins and ozokerite are quite safe and are also used for medical purposes for the direct heating of sore spots on the body.

However, with good heat capacity, their thermal conductivity is very low - so small that paraffin or ozokerite applied to the body, heated to 50-60 ° C, feels only pleasantly hot, but not scalding, as it would be with water heated to the same temperature. - this is good for medicine, but for a heat accumulator it is an absolute disadvantage. In addition, these substances are not so cheap, say, the wholesale price for ozokerite in September 2009 was about 200 rubles per kilogram, and a kilogram of paraffin cost from 25 rubles (technical) to 50 and more (highly purified food, i.e. suitable for use in product packaging). These are wholesale prices for consignments of several tons, at retail prices are more and more expensive at least one and a half times.

As a result, the economic efficiency of the paraffin heat accumulator turns out to be a big question, - after all, a kilogram or two of paraffin or ozokerite is suitable only for medical warming up of the broken lower back for a couple of tens of minutes, and to ensure a stable temperature of a more or less spacious dwelling for at least a day, the mass of the paraffin heat accumulator should be measured in tons, so that its cost immediately approaches the cost of a passenger car (albeit in the lower price segment)!

And the temperature of the phase transition, ideally, should nevertheless exactly correspond to the comfortable range (20..25 ° C) - otherwise, you will still have to organize some kind of heat exchange control system. Nevertheless, the melting point in the region of 50 ... 54 ° C, typical for highly purified paraffins, in combination with the high heat of phase transition (slightly more than 200 kJ / kg) is very suitable for a heat accumulator designed to provide hot water supply and hot water heating. the only problem is low thermal conductivity and high price of paraffin.

But in the case of force majeure, the paraffin itself can be used as a fuel with a good calorific value (although this is not so easy to do - unlike gasoline or kerosene, liquid and even more solid paraffin does not burn in air, you definitely need a wick or other device for feeding into the combustion zone not the paraffin itself, but only its vapors)!

An example of a melting and crystallizing thermal energy storage system is the silicon-based TESS thermal energy storage system developed by the Australian company Latent Heat Storage.

Evaporation and condensation

The heat of vaporization-condensation, as a rule, is several times higher than the heat of fusion-crystallization. And it seems that there are not so few substances that evaporate in the required temperature range. In addition to the frankly poisonous carbon disulfide, acetone, ethyl ether, etc., there is also ethyl alcohol (its relative safety is daily proved by personal example by millions of alcoholics around the world!). Under normal conditions, alcohol boils at 78 ° C, and its heat of vaporization is 2.5 times higher than the heat of fusion of water (ice) and is equivalent to heating the same amount of liquid water by 200 °.

However, unlike melting, when changes in the volume of a substance rarely exceed a few percent, during evaporation, vapor occupies the entire volume provided to it. And if this volume is unlimited, then the steam will evaporate, irrevocably taking with it all the accumulated energy. In a closed volume, the pressure will immediately begin to increase, preventing the evaporation of new portions of the working fluid, as is the case in the most ordinary pressure cooker, therefore, only a small percentage of the working substance experiences a change in the state of aggregation, while the rest continues to heat up while in the liquid phase. Here a large field of activity opens up for inventors - the creation of an efficient heat accumulator based on evaporation and condensation with a hermetically sealed variable displacement.

Phase transitions of the second kind

In addition to phase transitions associated with a change in the state of aggregation, some substances and within one state of aggregation can have several different phase states. A change in such phase states, as a rule, is also accompanied by a noticeable release or absorption of energy, although usually much less significant than with a change in the state of aggregation of matter. In addition, in many cases, with such changes, in contrast to the change in the state of aggregation, temperature hysteresis takes place - the temperatures of the forward and reverse phase transitions can differ significantly, sometimes by tens or even hundreds of degrees.

Electrical energy storage

Electricity is the most convenient and versatile form of energy in the world today. It is not surprising that it is the storage of electrical energy that is developing most rapidly. Unfortunately, in most cases the specific capacity of inexpensive devices is small, and devices with a high specific capacity are still too expensive for storing large energy reserves in mass use and are very short-lived.

Capacitors

The most popular "electrical" energy storage devices are conventional radio-technical capacitors. They have a tremendous rate of accumulation and release of energy - as a rule, from several thousand to many billions of complete cycles per second, and are able to operate in this way in a wide temperature range for many years, or even decades. By combining several capacitors in parallel, you can easily increase their total capacity to the desired value.

Capacitors can be divided into two large classes - non-polar (usually "dry", that is, not containing a liquid electrolyte) and polar (usually electrolytic). The use of a liquid electrolyte provides a significantly higher specific capacity, but almost always requires that the polarity be observed when connecting. In addition, electrolytic capacitors are often more sensitive to external conditions, primarily to temperature, and have a shorter service life (over time, the electrolyte evaporates and dries up).

However, capacitors have two main disadvantages. First, it is a very low specific density of stored energy and therefore a small (relative to other types of storage) capacity. Secondly, this is a short storage time, which is usually calculated in minutes and seconds and rarely exceeds several hours, and in some cases is only small fractions of a second. As a result, the scope of application of capacitors is limited by various electronic circuits and short-term accumulation sufficient for rectifying, correcting and filtering current in power electrical engineering - there is still not enough of them for more.

Supercapacitors

Ionistors, sometimes referred to as "supercapacitors", can be viewed as a kind of intermediate link between electrolytic capacitors and electrochemical batteries. From the former, they inherited an almost unlimited number of charge-discharge cycles, and from the latter, relatively low charging and discharging currents (a full charge-discharge cycle can last a second, or even much longer). Their capacity is also in the range between the most capacious capacitors and the smallest batteries - usually the energy reserve is from a few to several hundred joules.

Additionally, one should note the rather high sensitivity of the supercapacitors to temperature and the limited storage time of the charge - from several hours to several weeks maximum.

Electrochemical batteries

Electrochemical batteries were invented in the early days of electrical engineering and can now be found everywhere - from mobile phones to airplanes and ships. Generally speaking, they work on the basis of certain chemical reactions and therefore they could be attributed to the next section of our article - "Chemical energy storage". But since this point is usually not emphasized, but attention is drawn to the fact that batteries store electricity, we will consider them here.

As a rule, when it is necessary to store a sufficiently large energy - from several hundred kilojoules and more - lead-acid batteries are used (for example, any car). However, they have considerable dimensions and, most importantly, weight. If you need a light weight and mobility of the device, then more modern types of batteries are used - nickel-cadmium, metal-hydride, lithium-ion, polymer-ion, etc. They have a much higher specific capacity, but they also have a specific cost of energy storage. much higher, so their use is usually limited to relatively small and economical devices such as mobile phones, cameras and camcorders, laptops, etc.

In recent years, high-power lithium-ion batteries have begun to be used in hybrid cars and electric vehicles. In addition to lower weight and higher specific capacity, unlike lead-acid ones, they allow almost full use of their nominal capacity, are considered more reliable and have a longer service life, and their energy efficiency in a full cycle exceeds 90%, while the energy efficiency of lead-acid batteries, when the last 20% of the capacity is charged, the capacity can drop to 50%.

According to the mode of use, electrochemical batteries (primarily powerful ones) are also divided into two large classes - the so-called traction and starting ones. Usually, a starter battery can work quite successfully as a traction battery (the main thing is to control the degree of discharge and not bring it to such a depth, which is permissible for traction batteries), but when used in reverse, too large a load current can very quickly disable the traction battery.

The disadvantages of electrochemical batteries include a very limited number of charge-discharge cycles (in most cases, from 250 to 2000, and even in the absence of active operation, most types of batteries degrade after a few years, losing their consumer properties. ...

At the same time, the service life of many types of batteries does not go from the beginning of their operation, but from the moment of manufacture. In addition, electrochemical batteries are characterized by sensitivity to temperature, a long charge time, sometimes tens of times longer than the discharge time, and the need to comply with the method of use (prevention of deep discharge for lead-acid batteries and, conversely, compliance with a full charge-discharge cycle for metal-hydride and many other types of batteries). Charge storage time is also quite limited - usually from a week to a year. For old batteries, not only the capacity decreases, but also the storage time, and both can be reduced many times.

Developments with the aim of creating new types of electric batteries and improving existing devices do not stop.

Chemical energy storage

Chemical energy is energy “stored” in the atoms of substances, which is released or absorbed during chemical reactions between substances. Chemical energy is either released in the form of heat during exothermic reactions (for example, fuel combustion), or converted into electrical energy in galvanic cells and batteries. These energy sources are characterized by high efficiency (up to 98%), but low capacity.

Chemical energy storage devices allow you to receive energy in the form from which it was stored, and in any other. There are "fuel" and "non-fuel" varieties. Unlike low-temperature thermochemical storage devices (about them a little later), which can store energy simply by being placed in a warm enough place, here you cannot do without special technologies and high-tech equipment, sometimes very bulky. In particular, if, in the case of low-temperature thermochemical reactions, the mixture of reagents is usually not separated and is always in the same container, the reagents for high-temperature reactions are stored separately from each other and are combined only when energy is needed.

Energy storage through fuel production

During the energy storage stage, a chemical reaction takes place, as a result of which fuel is reduced, for example, hydrogen is released from water - by direct electrolysis, in electrochemical cells using a catalyst, or by thermal decomposition, say, by an electric arc or highly concentrated sunlight. The "released" oxidizer can be collected separately (for oxygen it is necessary in a closed isolated object - under water or in space) or "thrown away" as unnecessary, since at the time of fuel use this oxidizer will be quite enough in the environment and there is no need to waste space and funds for its organized storage.

At the stage of energy extraction, the spent fuel is oxidized with the release of energy directly in the desired form, regardless of how this fuel was obtained. For example, hydrogen can immediately produce heat (when burned in a burner), mechanical energy (when fed as fuel to an internal combustion engine or turbine), or electricity (when oxidized in a fuel cell). As a rule, such oxidation reactions require additional initiation (ignition), which is very convenient for controlling the process of energy recovery.

This method is very attractive because of the independence of the stages of energy storage ("charging") and its use ("discharge"), the high specific capacity of the energy stored in the fuel (tens of megajoules per kilogram of fuel) and the possibility of long-term storage (provided that the containers are properly sealed - for many years ). However, its wide distribution is hindered by incomplete development and high cost of technology, high fire and explosion hazard at all stages of work with such fuel, and, as a consequence, the need for highly qualified personnel in the maintenance and operation of these systems. Despite these shortcomings, various installations are being developed in the world that use hydrogen as a backup energy source.

Energy storage through thermochemical reactions

A large group of chemical reactions has long been widely known, which in a closed vessel, when heated, go in one direction with the absorption of energy, and when cooled, in the opposite direction with the release of energy. Such reactions are often called thermochemical. The energy efficiency of such reactions, as a rule, is less than with a change in the state of aggregation of a substance, but it is also very noticeable.

Such thermochemical reactions can be considered as a kind of change in the phase state of a mixture of reagents, and the problems arise here about the same - it is difficult to find a cheap, safe and effective mixture of substances that successfully acts in this way in the temperature range from + 20 ° C to + 70 ° C. However, one such composition has been known for a long time - it is Glauber's salt.

Mirabilite (aka Glauber's salt, aka sodium sulphate decahydrate Na2SO4 · 10H2O) is obtained as a result of elementary chemical reactions (for example, when table salt is added to sulfuric acid) or is mined as a “ready-made” mineral.

From the point of view of heat accumulation, the most interesting feature of mirabilite is that when the temperature rises above 32 ° C, bound water begins to be released, and outwardly it looks like a "melting" of crystals that dissolve in the water released from them. When the temperature drops to 32 ° C, free water is again bound into the structure of the crystalline hydrate - "crystallization" occurs. But the most important thing is that the heat of this hydration-dehydration reaction is very high and amounts to 251 kJ / kg, which is noticeably higher than the heat of "honest" melting-crystallization of paraffins, although it is one third less than the heat of melting of ice (water).

Thus, a heat accumulator based on a saturated solution of mirabilite (saturated precisely at temperatures above 32 ° C) can effectively maintain the temperature at 32 ° C with a large resource of energy storage or release. Of course, this temperature is too low for a full-fledged hot water supply (a shower with such a temperature is at best perceived as "very cool"), but this temperature may be quite enough for heating the air.

Fuel-free chemical energy storage

In this case, at the stage of "charging" from some chemicals, others are formed, and during this process, energy is stored in the new chemical bonds that are formed (for example, slaked lime is converted into an unslaked state with the help of heating).

When "discharging", a reverse reaction occurs, accompanied by the release of previously stored energy (usually in the form of heat, sometimes additionally in the form of gas, which can be supplied to the turbine) - in particular, this is exactly what happens when lime is "quenched" with water. Unlike fuel methods, to start a reaction, it is usually sufficient to simply combine the reagents with each other - no additional initiation of the process (ignition) is required.

In fact, this is a kind of thermochemical reaction, however, unlike the low-temperature reactions described when considering thermal energy storage devices and do not require any special conditions, here we are talking about temperatures of many hundreds or even thousands of degrees. As a result, the amount of energy stored in each kilogram of the working substance increases significantly, but the equipment is many times more complex, voluminous and more expensive than empty plastic bottles or a simple reagent tank.

The need to consume an additional substance - say, water for slaking lime - is not a significant drawback (if necessary, you can collect the water released during the transition of lime to the quicklime state). But the special storage conditions for this very quicklime, the violation of which is fraught not only with chemical burns, but also with an explosion, translate this and similar methods into the category of those that are unlikely to come out into widespread life.

Other types of energy storage

In addition to those described above, there are other types of energy storage devices. However, at present they are very limited in terms of the density of stored energy and its storage time at a high unit cost. Therefore, while they are more used for entertainment, and their exploitation for any serious purposes is not considered. An example is phosphorescent paints, which store energy from a bright light source and then glow for a few seconds or even long minutes. Their modern modifications do not contain toxic phosphorus for a long time and are quite safe even for use in children's toys.

Superconducting magnetic energy storage devices store it in the field of a large DC magnetic coil. It can be converted to alternating electrical current as needed. Low-temperature accumulators are cooled with liquid helium and are available for industrial applications. High temperature storage units cooled by liquid hydrogen are still under development and may become available in the future.

Superconducting magnetic energy storage devices are large in size and are typically used for short periods of time, such as during switchings. published by

How exactly is energy stored in ATF(adenosine triphosphate), and how is it given to do some useful work? It seems incredibly difficult that some abstract energy suddenly receives a material carrier in the form of a molecule inside living cells, and that it can be released not in the form of heat (which is more or less understandable), but in the form of creating another molecule. Usually the authors of textbooks limit themselves to the phrase "energy is stored in the form of a high-energy bond between the parts of a molecule, and is released when this bond is broken, doing useful work," but this does not explain anything.

In the most general terms, these manipulations with molecules and energy happen like this: first. Or they are created in chloroplasts in a chain of similar reactions. This is spent on the energy obtained during the controlled combustion of nutrients directly inside the mitochondria or the energy of the photons of sunlight falling on the chlorophyll molecule. Then ATP is delivered to those places of the cell where it is necessary to do some work. And when one or two phosphate groups are split off from it, energy is released, which does this work. In this case, ATP breaks down into two molecules: if only one phosphate group is split off, then ATP turns into ADP(adenosine DIPhosphate, which differs from adenosine TRIPhosphate only by the absence of the same separated phosphate group). If ATP gives up two phosphate groups at once, then more energy is released, and adenosine MONOPhosphate remains from ATP ( AMF).

Obviously, the cell also needs to carry out the opposite process, converting ADP or AMP molecules into ATP, so that the cycle can repeat itself. But these “blank” molecules can safely float next to the phosphates that are missing for them to convert into ATP, and never combine with them, because such a combination reaction is energetically disadvantageous.

What is the "energy gain" of a chemical reaction is quite easy to understand if you know about second law of thermodynamics: in the universe or in any system isolated from the rest, disorder can only grow. That is, complex molecules sitting in a cell in orderly order, in accordance with this law, can only be destroyed, forming smaller molecules or even decaying into individual atoms, because then the order will be noticeably less. To understand this idea, you can compare a complex molecule with an airplane assembled from Lego. Then the small molecules, into which the complex disintegrates, will be associated with individual parts of this plane, and the atoms - with individual Lego cubes. Looking at a neatly assembled plane and comparing it to a jumbled pile of parts, it becomes clear why complex molecules contain more order than small ones.

Such a disintegration reaction (of molecules, not of an airplane) will be energetically favorable, which means it can be carried out spontaneously, and energy will be released during the disintegration. Although, in fact, splitting the plane will be energetically beneficial: despite the fact that the parts themselves will not split off from each other, and outside force will have to puff over their uncoupling in the form of a kid who wants to use these parts for something else, he will spend on turning the plane into a chaotic pile of parts the energy obtained from eating highly ordered food. And the more densely the parts are stuck together, the more energy will be spent, including released in the form of heat. Bottom line: a piece of a bun (a source of energy) and an airplane turned into a disordered mass, the air molecules around the child warmed up (which means they move more randomly) - there is more chaos, that is, splitting the airplane is energetically beneficial.

To summarize, we can formulate the following rules following from the second law of thermodynamics:

1. With a decrease in the amount of order, energy is released, energetically favorable reactions occur

2. With an increase in the amount of order, energy is absorbed, energy-consuming reactions occur

At first glance, this inevitable movement from order to chaos makes it impossible to reverse processes, such as the construction of a single fertilized egg and nutrient molecules absorbed by the mother cow, undoubtedly very orderly compared to the chewed grass calf.

But nevertheless, this happens, and the reason for this is that living organisms have one chip that allows both to support the aspiration of the Universe to entropy, and to build themselves and their offspring: they combine two reactions into one process, one of which is energetically favorable, and the other is energy-consuming... By such a combination of the two reactions, it is possible to ensure that the energy released during the first reaction overlaps the energy consumption of the second in excess. In the example of an airplane, taking it apart separately is energy-intensive, and without a third-party source of energy in the form of a bun destroyed by the kid's metabolism, the airplane would stand forever.

It's like riding downhill on a sled: first, a person, while absorbing food, stores energy obtained as a result of energetically favorable processes of splitting a highly ordered chicken into molecules and atoms in his body. And then he spends this energy, pulling the sled up the mountain. Moving the sled from the foot to the top is energetically unprofitable, so they will never spontaneously roll there, this requires some kind of external energy. And if the energy received from eating chicken is not enough to overcome the rise, then the process of "sledging from the top of the mountain" will not happen.

It is the energy-consuming reactions ( energy-consuming reaction ) increase the amount of order by absorbing the energy released during the conjugate reaction. And the balance between the release and consumption of energy in these coupled reactions must always be positive, that is, their combination will increase the amount of chaos. An example of an increase entropy(disorder) ( entropy[‘Entrə pɪ]) is the release of heat during the energy-supplying reaction ( energy supply reaction): the particles of the substance adjacent to the molecules that have entered into the reaction receive energetic shocks from the reacting ones, begin to move faster and more chaotic, shoving in turn other molecules and atoms of this and neighboring substances.

Let's go back to getting energy from food: a piece of Banoffee Pie is much more orderly than the resulting mass that is chewed into the stomach. Which, in turn, consists of large, more ordered molecules than those into which the intestines break it down. And they, in turn, will be delivered to the cells of the body, where separate atoms and even electrons will be torn away from them ... And at each stage of the increase in chaos in a single piece of cake, energy will be released, which is captured by the organs and organelles of the happy eater, storing it in in the form of ATP (energy-intensive), allowing it to build new necessary molecules (energy-intensive) or to heat the body (also energy-intensive). As a result, in the system "man - Banoffee Pie - Universe" there is less order (due to the destruction of the cake and the release of heat energy by the organelles that process it), but in a separate human body there is more order of happiness (due to the emergence of new molecules, parts of organelles and whole cellular organs).

If we return to the ATP molecule, after all this thermodynamic retreat, it becomes clear that the creation of it from its constituent parts (smaller molecules) requires the expenditure of energy obtained from energetically favorable reactions. One of the ways to create it is described in detail, another (very similar) is used in chloroplasts, where the energy of photons emitted by the Sun is used instead of the energy of the proton gradient.

Three groups of reactions can be distinguished, as a result of which ATP is produced (see the diagram on the right):

• the splitting of glucose and fatty acids into large molecules in the cytoplasm already allows you to obtain a certain amount of ATP (a small amount, for one glucose molecule split at this stage there are only 2 obtained ATP molecules). But the main goal of this stage is to create molecules that are used in the respiratory chain of mitochondria.
• further cleavage of the molecules obtained at the previous stage in the Krebs cycle, proceeding in the mitochondrial matrix, gives only one ATP molecule, its main purpose is the same as in the previous paragraph.
• finally, the molecules accumulated at the previous stages are used in the respiratory chain of mitochondria for the production of ATP, and here a lot of it is released (more on this below).

If we describe all this in more detail, looking at the same reactions from the point of view of obtaining and spending energy, we get this:

0. Food molecules are gently burned (oxidized) in the primary cleavage that occurs in the cytoplasm of the cell, as well as in a chain of chemical reactions called the "Krebs cycle" that occurs already in the mitochondrial matrix - power supply part of the preparatory phase.

As a result of conjugation with these energetically favorable reactions of other, already energetically unfavorable reactions of creating new molecules, 2 ATP molecules and several molecules of other substances are formed - energy-consuming part of the preparatory phase. These incidentally formed molecules are carriers of high-energy electrons, which will be used in the respiratory chain of mitochondria in the next stage.

1. On the membranes of mitochondria, bacteria and some archaea, energetic elimination of protons and electrons from the molecules obtained in the previous stage (but not from ATP) occurs. The passage of electrons through the complexes of the respiratory chain (I, III, and IV in the diagram on the left) is shown by yellow winding arrows, the passage through these complexes (and therefore through the inner mitochondrial membrane) of protons is shown by red arrows.

Why can't electrons simply be split off from the carrier molecule using a powerful oxidizing agent, oxygen, and use the released energy? Why transfer them from one complex to another, because in the end they come to the same oxygen? It turns out that the greater the difference in the ability to attract electrons in the electron supply ( reductant) and electron collecting ( oxidizer) of the molecules participating in the electron transfer reaction, the more energy is released during this reaction.

The difference in this ability in the molecules-carriers of electrons and oxygen formed in the Krebs cycle is such that the energy released in this case would be sufficient for the synthesis of several ATP molecules. But because of such a sharp drop in the energy of the system, this reaction would proceed with almost explosive power, and almost all the energy would be released in the form of non-trapped heat, that is, in fact, it would be lost.

Living cells divide this reaction into several small stages, first transferring electrons from weakly attracting carrier molecules to a slightly stronger attracting first complex in the respiratory chain, from it to a slightly stronger attracting one. ubiquinone(or coenzyme Q-10), whose task is to drag electrons to the next, even slightly stronger attracting respiratory complex, which receives its part of the energy from this failed explosion, letting it go to pump protons through the membrane .. And so on until the electrons finally meet with oxygen, being attracted to it, capturing a couple of protons, and do not form a water molecule. This division of one powerful reaction into small steps allows almost half of the useful energy to be directed to doing useful work: in this case, to creating proton electrochemical gradient, which will be discussed in the second paragraph.

Exactly how the energy of the transmitted electrons helps the conjugated energy-consuming reaction of pumping protons through the membrane is just beginning to be elucidated. Most likely, the presence of an electrically charged particle (electron) affects the configuration of the place in the protein embedded in the membrane where it is located: so that this change provokes the proton being pulled into the protein and its movement through the protein channel in the membrane. What is important is that, in fact, the energy obtained as a result of the splitting off of high-energy electrons from the carrier molecule and their final transfer to oxygen is stored in the form of a proton gradient.

2. The energy of protons accumulated as a result of events from point 1 on the outer side of the membrane and striving to get to the inner side consists of two unidirectional forces:

• electric(the positive charge of protons tends to move to the place of accumulation of negative charges on the other side of the membrane) and
• chemical(as in the case of any other substances, protons try to scatter evenly in space, spreading from places with their high concentration to places where they are few)

The electrical attraction of protons to the negatively charged side of the inner membrane is a much more powerful force than the tendency arising from the difference in the concentration of protons to move to a place with a lower concentration (this is indicated by the width of the arrows in the diagram above). The combined energy of these attracting forces is so great that it is enough both for the movement of protons inside the membrane, and for feeding the accompanying energy-consuming reaction: the creation of ATP from ADP and phosphate.

Let us consider in more detail why energy is needed for this, and how exactly the energy of aspiration of protons is converted into the energy of a chemical bond between two parts of the ATP molecule.

The ADP molecule (in the diagram on the right) does not crave to acquire another phosphate group: the oxygen atom to which this group can attach is charged as negatively as phosphate, which means they are mutually repelled. And in general, ADP is not going to enter into reactions, it is chemically passive. Phosphate, in turn, has its own oxygen atom attached to the phosphorus atom, which could become the site of the bond between phosphate and ADP when creating an ATP molecule, so that it cannot show initiative either.

Therefore, these molecules must be bound by one enzyme, unfolded so that the bonds between them and the "extra" atoms weaken and break, and then bring the two chemically active ends of these molecules, where the atoms lack and excess electrons, to each other.

Phosphorus (P +) and oxygen (O -) ions caught in the field of mutual reach are bound by a strong covalent bond due to the fact that they jointly take possession of one electron, which originally belonged to oxygen. This molecule-processing enzyme is ATP synthase, and it receives energy to change both its configuration and the mutual arrangement of ADP and phosphate from protons passing through it. It is energetically advantageous for protons to get to the oppositely charged side of the membrane, where, moreover, there are few of them, and the only way is through the enzyme, the "rotor" of which the protons rotate along the way.

The structure of ATP synthase is shown in the diagram on the right. Its element rotating due to the passage of protons is highlighted in purple, and the moving picture below shows a diagram of its rotation and the creation of ATP molecules. The enzyme works almost like a molecular motor, converting electrochemical the energy of the proton current in mechanical energy friction of two sets of proteins against each other: the rotating "leg" rubs against the immobile proteins of the "mushroom cap", while the subunits of the "cap" change their shape. This mechanical deformation turns into chemical bond energy in the synthesis of ATP, when the ADP and phosphate molecules are processed and unfolded in the manner necessary for the formation of a covalent bond between them.

Each ATP synthase is capable of synthesizing up to 100 ATP molecules per second, and about three protons must pass through the synthetase for each synthesized ATP molecule. Most of the ATP synthesized in cells is formed in this way, and only a small part is the result of the primary processing of food molecules outside the mitochondria.

At any given time, there are roughly a billion ATP molecules in a typical living cell. In many cells, all this ATP is replaced (i.e. used and created again) every 1-2 minutes. The average person at rest uses about the same mass of ATP every 24 hours at rest.

In general, almost half of the energy released during the oxidation of glucose or fatty acids to carbon dioxide and water is captured and used for the energetically unfavorable reaction of ATP formation from ADP and phosphates. An efficiency of 50% is very good, for example, a car engine starts up only 20% of the energy contained in the fuel for useful work. At the same time, the rest of the energy in both cases is dissipated in the form of heat, and just like some cars, animals constantly spend this excess (although not completely, of course) to warm up the body. During the reactions mentioned here, one glucose molecule, gradually split into carbon dioxide and water, supplies the cell with 30 ATP molecules.

So, with where the energy comes from and how exactly it is stored in ATP, everything is more or less clear. It remains to understand how exactly the stored energy is released and what happens during this at the molecular-atomic level.

The covalent bond formed between ADP and phosphate is called high energy for two reasons:

• when it is destroyed, a lot of energy is released
• the electrons participating in the creation of this bond (that is, rotating around the oxygen and phosphorus atoms, between which this bond is formed) are high-energy, that is, they are in "high" orbits around the nuclei of atoms. And it would be energetically beneficial for them to jump to a lower level, releasing excess energy, but as long as they are in this place, holding together the oxygen and phosphorus atoms, they will not be able to “jump”.

This tendency of electrons to fall into a more convenient low-energy orbit ensures both the ease of breaking the high-energy bond and the energy released in the form of a photon (which is a carrier of electromagnetic interaction). Depending on which molecules will be substituted by enzymes to the disintegrating ATP molecule, which molecule will absorb the photon emitted by the electron, different variants of events can occur. But every time the energy stored in the form of a high-energy connection will be used for some of the needs of the cell:

Scenario 1: phosphate can be transferred to a molecule of another substance. In this case, high-energy electrons form a new bond, already between the phosphate and the extreme atom of this recipient molecule. The condition for such a reaction is its energy benefit: in this new bond, the electron should have slightly less energy than when it was part of the ATP molecule, emitting part of the energy in the form of a photon outside.

The purpose of such a reaction is to activate the receptor molecule (in the diagram on the left, it is indicated V-OH): before the addition of phosphate, it was passive and could not react with another passive molecule A, but now she is the owner of a reserve of energy in the form of a high-energy electron, which means she can spend it somewhere. For example, to attach a molecule to itself A, which is impossible to attach without such a trick with the ears (that is, the high energy of the binding electron). At the same time, the phosphate is detached, having done its job.

It turns out such a chain of reactions:

1. ATF+ passive molecule V ➡️ ADP+ molecule active due to attached phosphate B-P

2. activated molecule B-P+ passive molecule A➡️ connected molecules A-B+ split off phosphate ( R)

Both of these reactions are energetically favorable: each of them involves a high-energy bonding electron, which, when one bond is destroyed and another is built, loses part of its energy in the form of photon emission. As a result of these reactions, two passive molecules joined together. If we consider the reaction of the connection of these molecules directly (passive molecule V+ passive molecule A➡️ connected molecules A-B), then it turns out to be energetically costly and cannot be accomplished. Cells “do the impossible” by pairing this reaction with the energetically favorable reaction of splitting ATP into ADP and phosphate during the two reactions described above. Cleavage occurs in two stages, at each of which part of the energy of the bonding electron is spent on doing useful work, namely on creating the necessary bonds between two molecules, from which the third ( A-B), necessary for the functioning of the cell.

Scenario 2: phosphate can be split off at once from the ATP molecule, and the released energy is captured by the enzyme or working protein and spent on doing useful work.

How can you catch something so imperceptible as an insignificant disturbance of the electromagnetic field at the moment an electron falls into a lower orbit? It's very simple: with the help of other electrons and with the help of atoms capable of absorbing the photon released by the electron.

The atoms that make up the molecules are held together in strong chains and rings (such a chain is the unfolded protein in the picture on the right). And the individual parts of these molecules are attracted to each other by weaker electromagnetic interactions (for example, hydrogen bonds or van der Waals forces), which allows them to fold into complex structures. Some of these configurations of atoms are very stable, and no disturbance of the electromagnetic field will shake them .. will not shake them .. in general, they are stable. And some are quite mobile, and a light electromagnetic kick is enough for them to change their configuration (usually these are not covalent bonds). And just such a kick is given to them by the same arriving photon-carrier of the electromagnetic field, emitted by the electron that has passed into a lower orbit when the phosphate is detached.

Protein configuration changes resulting from the breakdown of ATP molecules are responsible for some of the most amazing happenings in the cell. Surely those who are interested in cellular processes at least at the level of "watch their animation on youtube" stumbled upon a video showing a protein molecule kinesin, in the literal sense of the word, walking, rearranging her legs, along the thread of the cell skeleton, dragging the weight attached to it.

It is the cleavage of phosphate from ATP that provides this stepping, and here's how:

Kinesin ( kinesin) refers to a special type of protein, which tend to spontaneously change its conformation(the relative position of atoms in a molecule). Left alone, it randomly transitions from conformation 1, in which it is attached with one "leg" to an actin filament ( actin filament) - the thinnest thread forming cytoskeleton cells ( cytoskeleton), into conformation 2, thus making a step forward and standing on two "legs". It will pass from conformation 2 with equal probability both to conformation 3 (attaches the hind leg to the front), and back to conformation 1. Therefore, the movement of kinesin in any direction does not occur, it simply flans aimlessly.

But everything changes, as soon as it connects with the ATP molecule. As shown in the diagram on the left, the addition of ATP to kinesin, which is in conformation 1, leads to a change in its spatial position and it changes to conformation 2. The reason for this is the mutual electromagnetic influence of ATP and kinesin molecules on each other. This reaction is reversible, because no energy has been expended, and if ATP is detached from kinesin, it will simply raise its “leg”, remaining in place, and wait for the next ATP molecule.

But if it lingers, then due to the mutual attraction of these molecules, the bond that holds the phosphate within the ATP is destroyed. The energy released at the same time, as well as the breakdown of ATP into two molecules (which have a different effect on the kinesin atoms with their electromagnetic fields) lead to the fact that the kinesin conformation changes: it "drags the hind leg". It remains to take a step forward, which is what happens during the detachment of ADP and phosphate, which returns kinesin to its original conformation 1.

As a result of hydrolysis of ATP, kinesin shifted to the right, and as soon as the next molecule joins it, it will take another couple of steps, using the energy stored in it.

It is important that kinesin, which is in conformation 3 with attached ADP and phosphate, cannot return to conformation 2 by taking a "step back". This is explained by the same principle of compliance with the second law of thermoregulation: the transition of the "kinesin + ATP" system from conformation 2 to conformation 3 is accompanied by the release of energy, which means that the reverse transition will be energy-consuming. For it to happen, you need to take energy from somewhere to combine ADP with phosphate, but there is nowhere to take it in this situation. Therefore, kinesin connected to ATP is open only in one direction, which allows us to do useful work of dragging something from one end of the cell to the other. Kinesin, for example, is involved in pulling apart the chromosomes of a dividing cell during mitosis(the process of division of eukaryotic cells). Muscle protein myosin runs along the actin filaments, causing muscle contraction.

This movement is very fast: some motor(responsible for various forms of cell motility) proteins involved in gene replication rush along the DNA chain at a speed of thousands of nucleotides per second.

They all move at the expense of hydrolysis ATP (destruction of the molecule with attachment to the resulting decomposition of smaller molecules of atoms taken from the water molecule. Hydrolysis is shown on the right side of the diagram of the interconversion of ATP and ADP). Or by hydrolysis GTF, which differs from ATP only in that it contains another nucleotide (guanine).

Scenario 3: cleavage of two phosphate groups from ATP or other similar molecule containing a nucleotide at once leads to an even greater release of energy than when only one phosphate is cleaved. Such a powerful release allows you to create a strong sugar-phosphate backbone of DNA and RNA molecules:

1. in order for nucleotides to be able to attach to the under construction DNA or RNA strand, they must be activated by attaching two phosphate molecules. This is an energy-intensive reaction performed by cellular enzymes.

2. the enzyme DNA or RNA polymerase (not shown in the diagram below) attaches an activated nucleotide (GTP is shown in the diagram) to the polynucleotide under construction and catalyzes the cleavage of two phosphate groups. The released energy is used to create a bond between the phosphate group of one nucleotide and the ribose of another. The bonds created as a result are not high-energy, which means that it is not easy to destroy them, which is an advantage for building a molecule that contains the hereditary information of the cell or transmits it.

In nature, only energetically favorable reactions can occur spontaneously, which is due to the second law of thermodynamics

Nevertheless, living cells can combine two reactions, one of which gives a little more energy than the other absorbs, and thus carry out energy-consuming reactions. Energy-consuming reactions are aimed at creating larger molecules, cellular organelles and whole cells, tissues, organs and multicellular living beings from individual molecules and atoms, as well as at storing energy for their metabolism

Energy storage is carried out due to the controlled and gradual destruction of organic molecules (energy-supplying process), coupled with the creation of energy-carrier molecules (energy-consuming process). Thus, photosynthetic organisms store the energy of solar photons captured by chlorophyll.

Energy carrier molecules are divided into two groups: storing energy in the form of a high-energy bond or in the form of an attached high-energy electron. However, in the first group, high energy is provided by the same high-energy electron, so we can say that energy is stored in electrons driven to a high level, which are part of different molecules

The energy stored in this way is also given off in two ways: by breaking the high-energy bond or by transferring high-energy electrons to gradually reduce their energy. In both cases, energy is released in the form of emission by the electron transferring to a lower energy level of the particle-carrier of the electromagnetic field (photon) and heat. This photon is captured in such a way that useful work is done (the formation of a molecule necessary for metabolism in the first case and the pumping of protons through the mitochondrial membrane in the second)

The energy stored in the proton gradient is used for the synthesis of ATP, as well as for other cellular processes that are beyond the scope of this chapter (I think no one is offended, given its size). And the synthesized ATP is used as described in the previous paragraph.

Lactic acid (accumulating in the muscles can cause pain) is delivered by the blood to the liver, where it is converted into glucose during gluconeogenesis.

Alcohol forms in yeast cells during alcoholic fermentation.

acetyl-CoA - is used for the synthesis of HFA, ketone bodies, cholesterol, etc. or is oxidized in the Krebs cycle.

Water and carbon dioxide are included in the general metabolism or excreted from the body.

Pentoses are used for the synthesis of nucleic acids, glucose (gluconeogenesis), and other substances.

NADPH2 participates in the synthesis of HFA substances, purine bases, etc. or is used to generate energy in the CPE.

• Energy is stored in the form of ATP, which is then used in the body for the synthesis of substances, the release of heat, muscle contractions, etc.

The transformation of glucose in the body is quite complex processes that proceed under the action of various enzymes. So the path from glucose to lactic acid includes 11 chemical reactions, each of which is accelerated by its own enzyme.

Scheme No. 8. Anaerobic glycolysis.

Glucose

ADP Hexokinase, ion Mg

Glucose-6-phosphate

Phosphoglucoisomerase

Fructose-6-phosphate

ADP Phosphofructokinase, Mg ions

Fructose-1,6-diphosphate

Aldolase

3-Phosphodioxyacetone 3-Phosphoglyceroaldehyde (3-PHA)

NADH + H 3-PHA dehydrogenase

1,3-diphosphoglyceric acid

ATP Phosphoglyceratmutase

2-phosphoglyceric acid

H2O Enolase

Phosphoenolpyruvic acid

ATP Pyruvate kinase, Mg ions

Pyruvic acid PVC

OVER Lactate dehydrogenase

Lactic acid.

Glycolysis occurs in the cytoplasm of cells and does not require a mitochondrial respiratory chain.

Glucose is one of the main sources of energy for cells of all organs and tissues, especially the nervous system, erythrocytes, kidneys and testes.

The brain is supplied almost entirely by diffusely supplied glucose. IVH does not penetrate into brain cells. Therefore, with a decrease in the concentration of glucose in the blood, the functioning of the brain is disrupted.

Gluconeogenesis.

Under anaerobic conditions, glucose is the only source of energy for skeletal muscle function. The lactic acid formed from glucose then enters the bloodstream, to the liver, where it is converted into glucose, which is then returned to the muscles (the measles cycle).

The process of converting non-carbohydrate substances into glucose is called gluconeogenesis.

The biological significance of gluconeogenesis is as follows:

Maintaining the concentration of glucose at a sufficient level when there is a lack of carbohydrates in the body, for example, during fasting or diabetes mellitus.

Formation of glucose from lactic acid, pyruvic acid, glycerol, glycogenous amino acids, most of the intermediate metabolites of the Krebs cycle.

Gluconeogenesis occurs mainly in the liver and renal cortex. In the muscles, this process does not take place due to the lack of essential enzymes.

The total reaction of gluconeogenesis:

2PVK + 4ATF + 2GTP + 2NADH + H + 4H2O

glucose + 2NAD + 4ADP + 2GDF + 6H3PO4

Thus, in the process of gluconeogenesis, up to 6 high-energy compounds and 2NADH + H are spent for each glucose molecule.

Consuming large amounts of alcohol inhibits gluconeogenesis, which can lead to decreased brain function. The rate of gluconeogenesis can increase in the following conditions:

When fasting.

Enhanced protein nutrition.

Lack of carbohydrates in food.

Diabetes mellitus.

Glucuronic pathway of glucose metabolism.

This pathway is insignificant in quantitative terms, but very important for the detoxification function: the end products of metabolism and foreign substances, binding to the active form of glucuronic acid (UDP-glucuronic acid) in the form of glucuronides, are easily excreted from the body. Glucuronic acid itself is a necessary component of glycosaminoglycans: hyaluronic acid, heparin, etc. In humans, as a result of this pathway of glucose breakdown, UDP-glucuronic acid is formed.

All living organisms, except viruses, consist of cells. They provide all the processes necessary for the life of a plant or animal. The cell itself can be a separate organism. And how can such a complex structure live without energy? Of course not. So how does the supply of energy to cells take place? It is based on the processes that we will discuss below.

Providing cells with energy: how does it happen?

Few cells receive energy from the outside, they generate it themselves. possess a kind of "stations". And the source of energy in the cell is the mitochondria - the organoid that produces it. The process of cellular respiration takes place in it. Due to it, the cells are supplied with energy. However, they are present only in plants, animals and fungi. In bacterial cells, mitochondria are absent. Therefore, their supply of cells with energy occurs mainly due to fermentation processes, and not respiration.

Mitochondrion structure

This is a two-membrane organoid that appeared in a eukaryotic cell during evolution as a result of absorption of a smaller one.This can explain the fact that mitochondria have their own DNA and RNA, as well as mitochondrial ribosomes that produce proteins necessary for organelles.

The inner membrane has outgrowths called cristae, or ridges. The process of cellular respiration takes place on the cristae.

What is inside the two membranes is called the matrix. It contains proteins, enzymes necessary to accelerate chemical reactions, as well as RNA, DNA and ribosomes.

Cellular respiration is the basis of life

It takes place in three stages. Let's take a closer look at each of them.

The first stage is preparatory

During this stage, complex organic compounds are split into simpler ones. Thus, proteins break down to amino acids, fats to carboxylic acids and glycerol, nucleic acids to nucleotides, and carbohydrates to glucose.

Glycolysis

This is an oxygen-free stage. It consists in the fact that the substances obtained during the first stage are further degraded. The main sources of energy that the cell uses at this stage are glucose molecules. Each of them in the process of glycolysis breaks down to two molecules of pyruvate. This happens during ten successive chemical reactions. Due to the first five, glucose is phosphorylated and then split into two phosphotrioses. In the next five reactions, two molecules and two molecules of PVC (pyruvic acid) are formed. The energy of the cell is stored in the form of ATP.

The whole process of glycolysis can be simplified as follows:

2NAD + 2ADP + 2H 3 PO 4 + C 6 H 12 O 6 → 2H 2 O + 2NAD. H 2 + 2C 3 H 4 O 3 + 2ATF

Thus, using one glucose molecule, two ADP molecules and two phosphoric acid, the cell receives two ATP molecules (energy) and two pyruvic acid molecules, which it will use in the next step.

The third stage is oxidation

This stage occurs only in the presence of oxygen. The chemical reactions of this stage take place in the mitochondria. This is the main part during which the most energy is released. At this stage, reacting with oxygen, it decomposes to water and carbon dioxide. In addition, 36 ATP molecules are formed. So, we can conclude that the main sources of energy in the cell are glucose and pyruvic acid.

Summing up all the chemical reactions and omitting the details, we can express the entire process of cellular respiration in one simplified equation:

6O 2 + C 6 H 12 O 6 + 38ADP + 38H 3 PO 4 → 6CO 2 + 6H2O + 38ATF.

Thus, during respiration, from one glucose molecule, six oxygen molecules, thirty-eight ADP molecules and the same amount of phosphoric acid, the cell receives 38 ATP molecules, in the form of which energy is stored.

Variety of mitochondrial enzymes

The cell receives energy for vital activity due to respiration - oxidation of glucose, and then pyruvic acid. All these chemical reactions could not take place without enzymes - biological catalysts. Let's look at those of them that are found in mitochondria - organelles responsible for cellular respiration. All of them are called oxidoreductases, because they are needed to ensure the occurrence of redox reactions.

All oxidoreductases can be divided into two groups:

• oxidase;
• dehydrogenase;

Dehydrogenases, in turn, are divided into aerobic and anaerobic. Aerobic ones contain the coenzyme riboflavin, which the body receives from vitamin B2. Aerobic dehydrogenases contain NAD and NADP molecules as coenzymes.

Oxidases are more diverse. First of all, they are divided into two groups:

• those that contain copper;
• those that contain iron.

The former include polyphenol oxidases, ascorbate oxidase, the latter - catalase, peroxidase, cytochromes. The latter, in turn, are divided into four groups:

• cytochromes a;
• cytochromes b;
• cytochromes c;
• cytochromes d.

Cytochromes a contain iron-formylporphyrin, cytochromes b - iron protoporphyrin, c - substituted iron mesoporphyrin, d - iron dihydroporphyrin.

Are there other ways to get energy?

Despite the fact that most cells receive it as a result of cellular respiration, there are also anaerobic bacteria that do not need oxygen to exist. They generate the necessary energy through fermentation. This is a process during which, with the help of enzymes, carbohydrates are broken down without the participation of oxygen, as a result of which the cell receives energy. There are several types of fermentation, depending on the end product of chemical reactions. It can be lactic acid, alcoholic, butyric acid, acetone-butane, citric acid.

For example, consider It can be expressed with the following equation:

S 6 N 12 O 6 → C 2 H 5 OH + 2CO 2

That is, the bacterium splits one molecule of glucose into one molecule of ethyl alcohol and two molecules of carbon (IV) oxide.