Carbon dioxide, glucose and carbon life. What is glucose? Obtaining glucose and its properties
On the production of carbohydrates from carbon dioxide and water and the course of reactions in plants
Karpunin Ivan Ivanovich
Doctor of Technical Sciences, Professor, Professor of the Department of the Belarusian National Technical University, Academician of MIA and MAIT.
The most likely final reaction for the formation of hexoses from carbon dioxide and water, apparently, is 6CO 2 + 6H 2 O \u003d C 6 H 12 O 6 + 6O 2, pentose -10CO 2 + 10H 2 O \u003d 2C 5 H 10 O 4 + 11O 2 .
The effect of light sources on the course of physiological processes in vivo and on the biosynthesis of various substances in plants is described in the literature.
Carbohydrate composition and the quantitative content of carbohydrates was determined using chromatography on paper.
The analysis consisted of two parts: a) separation of monosaccharides using chromatography on paper; b) quantitative determination of separated monosaccharides.
It is known from literary sources that as a result of the assimilation of carbon dioxide by plants, d-glucose is formed, and formaldehyde is an intermediate product of this reaction: CO 2 + H 2 O \u003d CH 2 O + O 2, 6CH 2 O \u003d C 6 H 12 O 6 (glucose). The formation of formaldehyde as an intermediate product of photosynthesis is evidenced by experiments on the assimilation of carbon dioxide by purple bacteria containing a green pigment that resembled chlorophyll. As a result, the conversion of carbon dioxide was presented as an equation: CO 2 + 2H 2 A \u003d h (CH 2 O) + H 2 O + 2A, where H 2 A is a substance that supplies hydrogen for the CO 2 reduction reaction.
Moreover, if the substance supplying hydrogen is water, then oxygen is released. However, according to other researchers who used a radioactive isotope of carbon (C 11) to study the process of assimilation of CO 2, the first stage consists in the addition of carbon dioxide to aldehydes or alcohols. This reaction leads to the formation of hydroxy acids or ketone acids and proceeds without the influence of light (refers to reactions in the dark).
The second stage is the reduction of the ketone or carboxyl group. As a result, the first turns into a secondary alcohol group, and the second into an aldehyde group. In this reaction, where hydrogen gives up water, oxygen is released. This second reaction requires the influence of light to proceed.
Therefore, formaldehyde may not be an intermediate product in the synthesis of carbohydrates from carbon dioxide and water and, in particular, d-glucose.
Previously, we obtained carbohydrates from carbon dioxide and water and proposed a technology for their production. At the same time, the type of catalyst used and the amount of its introduction into the reaction mixture were not indicated, and the intensity of UV light irradiation was not indicated, which is the subject of “know-how”. In order to further improve the technology for obtaining carbohydrates, we carried out the following:
1) the temperature for obtaining carbohydrates has been changed;
2) studies were conducted without the use of UV light irradiation;
3) the time of the process of obtaining carbohydrates has been changed;
4) for the reaction (instead of pure isolated chlorophylls), xanthophyll and carotene (in a certain ratio) were used together with chlorophyll (a and b) to simplify the technology, since obtaining pure chlorophyll complicates the technology.
As a result, the yield of carbohydrates was increased to 9-10% in relation to the water taken for the reaction.
At the same time, in order to further improve the technology for obtaining carbohydrates (in order to increase the yield of carbohydrates), it is necessary to further improve it.
Literature
1. Nikitin V.M. Lignin. M.: Goslesbumizdat, 1961.-586 p.
2. Biochemistry of phenolic compounds. Per. from English. Edited by N.M. Emanuel. M.: Mir.-1988.- 541 p.
3. Nikitin N.I. Chemistry of wood and cellulose. M.-L.- 1962.- 710 p.
4. Lignins (structure, properties and reactions). Under the reaction of Sarkanen K.V. and Ludwig K.H. Per. from English. M.: Lesn. prom.- 1975.- 632 p.
5. Karpunin I.I., Karpunin A.V. On obtaining carbohydrates from carbon dioxide and water // Journal of graduate students and doctoral students. Kursk -2015, No. 3.- P.122.
6. Karpunin I.I. On the production of carbohydrates from carbon dioxide and water. Message 2 // Journal of postgraduates and doctoral students. Kursk -2015, No. 4.- P.132-133.
ENERGY OF LIFE.
This is a rather complex subject. The problems start with the name itself - whatever you call it, it will still be associated with "bioenergy", which is now in big fashion. No one knows what it is, but most are convinced that it is a powerful force that affects virtually everything, something like an evil spirit or divine providence, as you like. Meanwhile, as we have already understood, living organisms receive, transform and use the most common energy. This subject is beautiful in its own way, but we will talk about very complex processes, a clear understanding of which requires a certain education - this is the very biochemistry, and quite complicated at that. And since it concerns energy, knowledge of physical chemistry is necessary to understand it. However, it is necessary to familiarize you with the most important processes, at least superficially, so that you have a general idea of how this happens and at the same time feel the volume of the subject. To enhance your own interest in it, try to feel the fact that what we will now meet, like everything we have met so far, does not occur in some test tube in some laboratory (although it turned out there that how exactly it happens), but directly inside us, in every cell of our body, including the cells of the brain, with the help of which we are trying to understand something, at any moment and with great speed.
We started our introduction to biology with chemistry, then we move on to the cell, and then to the organism. As we move on to ever larger structures, that is, as we move away from the molecules and approach the objects that fill our everyday life, understanding will become easier and easier. And this is not surprising, since our brains were created by evolution in order to guide us in the macrocosm. Processes at the micro level proceed automatically and spontaneously, without our permission. But they were created in the same way in the course of evolution, only this happened at much earlier stages of it.
Biochemical processes in the body are the most complex ways of transformations of substances into one another and their transport from one place to another. These paths can be depicted schematically, resulting in diagrams of monstrous complexity, sometimes depicted on very instructive posters. In order to familiarize ourselves with these paths, we need to choose the thread with which to begin the journey through this labyrinth, and the point to which we should come. Let's start from the end.
Why does the body need energy? Almost all processes in it are carried out by enzymatic reactions, many of which require energy. As we remember, the vast majority of enzymatic reactions that proceed with the expenditure of energy require an ATP molecule (adenosine triphosphate), which is a universal energy carrier inside the cell, to proceed. Let us recall its structure again:
Energy is stored in bonds between three phosphoric acid residues connected in series (they are called macroergic bonds). In the course of "costly" enzymatic reactions, the ATP molecule is dephosphorylated and converted to ADP (adenosine diphosphate is almost the same molecule as one of the RNA monomers). It should be clarified that, in fact, the breaking of any chemical bond requires the expenditure of some amount of energy. However, the hydrolysis of a macroergic bond gives an energy gain, which is about 30 kJ / mol (and a mol is the Avogadro number of molecules, i.e. 6 1023 pieces). In addition, the cleavage reaction of a macroergic bond occurs only if the concentration of ATP significantly exceeds the concentration of its hydrolysis products, so living cells are forced to maintain it at a high level.
Muscle contraction - the first thing that comes to our mind as a powerful mechanical device in connection with the issue of energy costs - also requires ATP molecules. Although the action of contractile proteins is not an enzymatic reaction, its essence remains the same - a certain change in protein conformation during the hydrolysis of phosphodiester bonds in the ATP molecule. For some reason, they rarely remember energy costs in connection with higher nervous activity (probably, we are still more athletes and mechanisms than thinkers). And they are not small - remember how you want to eat in the process of studying. And the same ATP is consumed here.
So, we now need to consider how the body synthesizes its ATP. This molecule will be the final point of our journey.
Where do we start? Let's start with the glucose molecule. This substance is the energy carrier of our blood. It is it that is formed during the digestion of carbohydrates and fats of food and the consumption of fat reserves under the skin and glycogen in the liver. Again, glucose is the very first organic substance that plants form as a result of photosynthesis from carbon dioxide and water. In plants, glucose and fructose also serve as carriers of matter and energy - they are formed in leaves and transported to stems, roots, flowers, fruits. And finally, the same glucose is a nutrient for most bacteria.
So we're going to travel the biochemical pathways from glucose to ATP. The first is a universal energy carrier in a multicellular organism, and the second is a universal (and countable) energy carrier in a cell. Having slightly changed the analogy, we can say that we are going to consider the mechanism of currency conversion - from international to national (although people have different national currencies, and cells have the same one).
When unwinding a biochemical chain, it should be borne in mind that all processes of obtaining energy by living organisms occur as a result of redox reactions, in which an electron is transferred from one molecule (reductant, electron donor) to another (oxidizer, electron acceptor). In this case, either organic molecules or oxygen play the role of an electron acceptor. On the path we have chosen, both ways will meet
So, let's start from the moment when glucose enters the cell and is used precisely as an energy source (and not for building polysaccharides, for example). The end chemical products of this process are carbon dioxide and water. The same thing would happen if we just burned glucose. However, unlike combustion, the energy gain from such a recombination of atoms does not go into the environment in the form of thermal energy, but is accumulated in the form of energy of certain chemical bonds. The process itself is very complex and involves many organic matter a certain structure. Amid all this complexity, it is gratifying that the mechanism of this process is the same in most living beings.
And its first stage, which can take place in the absence of oxygen, is the same for everyone. It's called glycolysis. The general sequence of glycolysis is as follows. Two phosphoric acid residues are attached to the glucose molecule. The phosphorus-oxygen bond in phosphoric acid is energetically saturated, which destabilizes the molecule and facilitates its splitting into two phosphorylated trisaccharides. Dephosphorylation of trisaccharides is accompanied by coupled phosphorylation of adenosine with the formation of ATP. The trick is that the double phosphorylation of one glucose molecule requires the consumption of two ATP molecules, which are dephosphorylated to ADP. However, further transformation of each of the trisaccharides leads to the formation of two ATP molecules, and since glucose breaks down into two trisaccharides, a total of four ATP molecules are formed. This means a gain of two ATP molecules per glucose molecule. We are witnessing a molecular business, where a capital of two ATPs brings a 100% profit. But if the cell is alive, it will always have free working capital. (Recall again that ATP can only serve as an energy source at high concentrations.)
There is another energy gain in the process of glycolysis. There is such a substance - nicotinamide adenine dinucleotide (NAD). It is a coenzyme for several enzymes.
This is indeed a dinucleotide, one of its components is the well-known adenine. The other nucleotide contains a new nitrogenous base for us - nicotinic acid (this is not exactly the same as nicotine, but very close in structure). Like most coenzymes and their components, nicotinic acid is one of the vitamins - PP. NAD exists in two forms - reduced (NAD-H, here in the Russian notation you have to combine the Russian abbreviation and the Latin symbol for the hydrogen atom) and oxidized (NAD +), the latter is formed by taking away a hydrogen atom and an additional electron from NAD-H and represents a positively charged ion (Fig. 5.1). The reduced form is an energy-rich state, so reducing NAD+ to NAD-H requires energy.
The reduced form of HAD-H is a strong reducing agent, that is, an electron donor. At the same time, it is also a donor of hydrogen atoms. Further we will see that NAD-H plays an important role in the synthesis of ATP, i.e. in the processes of obtaining energy. But participation as an intermediary in the processes of splitting organic matter in order to obtain energy, its function is not limited. As we will see in the next lecture, the same molecule in a slightly modified form is the most important resource in the synthesis of organics, as a donor of hydrogen, electrons and energy. organics.
The process of glycolysis involves the reduction of the NAD+ molecule to NAD-H. In the anaerobic version of glycolysis, which occurs in the absence of oxygen, this molecule is subsequently oxidized again.
Glycolysis is a rather complex sequence of enzymatic reactions. Here is his circuit diagram:
And here is the complete diagram of glycolysis, with all the intermediates.
Glycolysis breaks down into several stages, each of which is catalyzed by certain enzymes:
1) the conversion of glucose into glucose-6-phosphate under the action of the enzyme glucokinase - this process takes one molecule of ATP;
Let's look at a purely schematic picture of this process, just to brush up on the principle of an enzymatic reaction.
2) isomerization - the conversion of glucose-6-phosphate to fructose-6-phosphate;
3) additional phosphorylation of fructose-6-phosphate - also comes with the cost of an ATP molecule;
4) cleavage of fructose-1,6-biphosphate into two phosphorylated triatomic sugars (triose phosphate): dihydroxyacetone phosphate and glyceraldehyde phosphate. These products are able to pass one into another with the help of a special enzyme - isomerase. Glyceraldehyde phosphate enters the subsequent reactions of glycolysis, which is thereby consumed, and it is replenished, including due to the conversion of dihydroxyacetone phosphate into it;
5) glyceraldehyde-3-phosphate is again phosphorylated, and free phosphoric acid from solution is used for this. Unlike all previous acts of phosphorylation, which took place with the consumption of an ATP molecule, this reaction is accompanied by an energy gain, which goes to restore the molecule of the oxidized form of nicatinamide adenine dinucleotide (NAD +) to its reduced form (NAD-H). The energy gain that is unusual for us, instead of energy loss during phosphorylation, can be explained by the fact that if in other cases the phosphate group is transferred from one molecule (ATP) to another (cleaved sugar), then in this case, during the reaction, the mutual neutralization of the anion also occurs ( one of the oxygens of the phosphoric acid residue from the solution) and the cation (NAD +), which provides the necessary energy;
6) the newly attached phosphoric acid residue is again split off, joining adenosine diphosphate - with the formation of the coveted ATP. If before the second phosphorylation we had glyceraldehyde-3-phosphate, now we have glycerate-3-phosphate - the aldehyde group has been replaced by an acid one, and this molecule is negatively charged;
7) the phosphate and hydroxyl groups change places;
8) a water molecule is split off from the resulting glycerate-2-phosphate with the formation of a double bond and an enol group - phosphoenolpyruvate is formed;
9) it is dephosphorylated with the formation of pyruvate (pyruvic acid), while the phosphoric acid residue again goes to the formation of an ATP molecule - the second in the course of triose conversion.
So, the result of glycolysis is pyruvate.
Most of the reactions of glycolysis are reversible, but a few are practically irreversible. Therefore, if necessary, on the contrary, the body uses other ways to synthesize glucose from pyruvate.
If we consider anaerobic, i.e., proceeding in the absence of oxygen, glycolysis, then pyruvate is reduced to lactate; in more familiar names, pyruvic acid - to lactic acid. In this case, two hydrogen atoms are added to the molecule and the ketone group turns into a hydroxyl group. As in any redox reaction, if something is reduced, something must, on the contrary, be oxidized. In this case, NAD-H is oxidized to NAD +, thus restoring the status quo - oxidized NAD + was included in the glycolysis reaction, and we got it.
It is glycolysis that is responsible for the well-known processes of souring (milk) and fermentation (vegetables, mushrooms, fish). It is lactic acid - lactate - that accumulates in sour-milk and salty products. In yeast, pyruvate is converted not to lactate, but to ethyl alcohol. This reaction does not take place in one step, but in two, and is also accompanied by the oxidation of NAD-H. Some bacteria reduce pyruvate to succinic or butyric acids.
One should not think that anaerobic glycolysis is the destiny of exclusively anaerobic bacteria such as the causative agent of botulism. With intense loads, the circulatory system does not have time to supply oxygen to the working muscles. At the same time, part of the pyruvate is not consumed, but converted into lactate, as in anaerobic bacteria, since NAD-H must be oxidized, if not with oxygen (when it is not enough), then with pyruvate, with the latter reduced to lactate. In most modern oxygen-breathing organisms, pyruvate is not converted to lactoate, but is utilized further. It enters a cascade of enzymatic reactions, during which oxygen is consumed, carbon dioxide is formed and ATP is synthesized. All these reactions together are called cellular respiration.
In most modern oxygen-breathing organisms, pyruvate is not converted to lactate, but is utilized further. It enters a cascade of enzymatic reactions, during which oxygen is consumed, carbon dioxide is formed and ATP is synthesized. All these reactions together are called cellular respiration.
Let us draw your attention to the fact that cellular respiration consists of two processes. During one of them, carbon is oxidized to carbon dioxide, but molecular oxygen is not consumed - oxygen atoms are taken from organic substances and water, which is not formed here, but consumed. In this case, excess hydrogen is formed, which is used to restore coenzymes. During the second process, the coenzymes are oxidized and donate hydrogen (which is first split into protons and electrons with different fates), this is where it binds with molecular oxygen to form water. ATP is formed predominantly during the second process. The first process is called the tricarboxylic acid cycle, or Krebs cycle, the second is called oxidative phosphorylation.
A reservation should be made regarding the location of the event. Remember that all living things are made up of cells. The cells of all multicellular organisms and some unicellular organisms have a cell nucleus - these organisms are called eukaryotes. The nucleus contains DNA. The contents of a cell outside the nucleus is called the cytoplasm. In the cytoplasm there are various organelles - certain structures. Among the organelles are the so-called mitochondria. They look like cylindrical bodies surrounded by a double membrane - external and internal. The inner membrane forms numerous folds inside the mitochondria - cristae. You have probably heard about the existence of mitochondria and that they are the energy stations of the cell.
The process of glycolysis discussed above occurs in the cytoplasm. Cellular respiration takes place in the mitochondria. To do this, the product of glycolysis - pyruvate - must get inside the mitochondria.
So we're in the mitochondria. Cascade of reactions cellular respiration begins with a reaction, one of the substrates of which is pyruvate, and one of the products is acetyl coenzyme-A, or acetyl-coA. Acetyl-coA is one of the most important substances in biochemical pathways. It is formed during the breakdown of sugars, fatty acids and some amino acids and is used in their synthesis. In all these cases, it is a reactive carrier of the acetyl group. In some reactions, it is used for the synthesis of organic substances, in others - for their "burning" as a fuel. Therefore, acetyl-coA is the most important mediator in many biochemical processes associated with metabolism and energy. Let's take a look at this wonderful stuff.
We again see the familiar nucleotide adenosine, then a rather long hydrocarbon chain, including nitrogen atoms and ending with a sulfur atom, to which the acetyl group is attached. (A molecule without an acetyl group is just coenzyme A.)
Acetyl-coA is formed with the consumption of a molecule of pyruvate during a complex reaction catalyzed by a whole complex of three enzymes and five coenzymes attached to the mitochondrial membrane - the pyruvate dehydrogenase complex. At the same time, a carbon dioxide molecule is split off from the pyruvate molecule, and the acetyl group remaining from it is attached to coenzyme A, with the formation of acetyl-coA. The reaction has an energy gain, which goes to the reduction of one NAD+ molecule to NAD-H. In this reaction, we see for the first time how a carbon atom passes from organic matter into carbon dioxide. Once again, we note that this occurs without the participation of molecular oxygen - oxygen also comes from organic matter.
There are several more such events ahead of us, so that eventually all three carbon atoms that were in the pyruvate molecule will go into carbon dioxide. Thus, all the carbon that came from glucose goes first to pyruvate, and then to carbon dioxide. Note that in all cases, again, the oxygen present in the composition of organic substances will be used. Where will the extra hydrogen atoms go? They will go to restore NAD+ to NAD-H and to restore another coenzyme. Recall that after glycolysis, we already have one reduced NAD-H molecule (which, in the presence of cellular respiration, is not spent on the conversion of pyruvate to lactate).
Acetyl Co-A enters a cyclic biochemical process called the Krebs cycle. It is named after Hans Krebs, who described it in 1937, for which he subsequently received Nobel Prize. The cycle is 10 consecutive chemical reactions, during which 10 organic acids are sequentially converted one into another. In one place, the already familiar acetyl-coA enters this cycle, which gives its acetyl group to oxaloacetate (oxaloacetic acid), resulting in the formation of citrate (citric acid). If the first molecule contained four carbon atoms, then the second, respectively, already contains six (there are two carbons in the acetyl group). Three of them are in carboxyl groups, and three make up the backbone of the molecule - such acids are called tricarboxylic acids.
Here is a diagram of the Krebs cycle.
It's good for everyone except for two things. The Krebs cycle is a closed chain of successive interconversions of ten different molecules, and this diagram shows only eight - where too many side reactions are shown along the arrows - the reduction of coenzymes and the elimination of CO2, in fact, two reactions occur with one more mediator. Secondly, it has been shown that ADP is phosphorylated with the formation of ATP, while in fact, GDP is phosphorylated there with the formation of GTP. The complete and correct scheme is presented in expanded form:
In the course of successive transformations of all these acids, events of several types occur:
– acids lose two carbon atoms due to the formation of two molecules of carbon dioxide;
- acids attach two water molecules;
- excess hydrogen is spent on the reduction of three NAD+ molecules to NAD-H, as well as on the reduction of another coenzyme - flavin adenine dinucleotide (FAD) to FAD-H2;
- one molecule of guanosine triphosphate (GTP) is formed from GDP. This is completely equivalent to the formation of ATP, since GTP and ATP are in chemical equilibrium.
The Krebs cycle closes when we eventually end up with the same oxaloacetate with its four carbons, which can again have an acetyl group attached from acetyl-coA.
All substances of the Krebs cycle - both acids and enzymes catalyzing reactions - are in the same solution inside the mitochondria (only one of the enzymes is immobilized on the membrane - it is the one that catalyzes the reaction with the formation of GTP), so the cycle has no spatial content - this just a sequence of transformations of substances. It plays a central role in cell metabolism, since the substances involved in it are intermediate substances in many metabolic processes. This cycle is involved in the breakdown and synthesis of carbohydrates, in the breakdown and synthesis of fatty acids, in the breakdown and synthesis of many amino acids, in the synthesis of nitrogenous bases of nucleotides and other important substances.
Three of the 10 acids that are cyclically converted to one another in the Krebs cycle, you may be familiar with. These are citric, succinic and malic acids. Branded formulations for the reinforcement of athletes contain not only glucose, but also citric acid. This is done in order not only to carry out an infusion of energy, but also to stimulate the entire Krebs cycle. Succinic acid is now actively advertised as a medicine that helps with almost everything, including strengthening the immune system. However, we have seen that this substance is always (at least as long as we breathe) present in the mitochondria and is in chemical equilibrium with citric acid.
As we have seen, during the formation of acetyl-coA and the Krebs cycle, only one molecule of nucleotide triphosphate (GTP, which is as good as ATP) is formed, although we have used up all three carbon atoms. The main commodity extracted from this complex commercial scam, which goes through many intermediaries that freely roam the interior of the mitochondria as brokers on the stock exchange, is reduced coenzymes. Let's now sell them for our favorite currency - ATP. To do this, we should contact a company called Electron Transport Chain.
Unlike the Krebs cycle, this firm has its own production room, however, floating. The process that will take place is carried out by three aggregates of certain proteins located on the inner membrane of the mitochondria. Just in case, let us explain that there are a lot of such individual aggregates (5–20 thousand per mitochondrion, and their three types are not in stoichiometric ratios); each of them is a workable workshop. Since the membrane is semi-liquid (we will consider its properties in more detail later), protein aggregates seem to float on the membrane like barges, transferring an electron to each other when colliding with one of the mobile substances - in one case with ubiquinone (a small molecule that includes an aromatic ring), in the other - with cytochrome c (about cytochromes - a little later). The very process that occurs as a result of electron transfer is called oxidative phosphorylation.
The electron transport chain begins with the NAD-H molecule donating two electrons to the NAD-H oxidase enzyme, turning into the oxidized form of NAD+. The resulting wroton goes into solution into the outer space of the mitochondria. NAD oxidase is the first of these protein aggregates. These two electrons are transferred by coupled redox reactions along the protein chain. Two more coenzymes are involved in this system: a special nucleotide - flavin mononucleotide and ubiquinone - a molecule that includes an aromatic ring
Proteins in the electron transport chain contain an iron atom, which changes its oxidation state from +3 to +2 and back during electron transport. With the exception of one of these proteins (ferrodoxin), in which the iron atom is connected to sulfur, in all the others the iron atom is located in the heme already familiar to us from the hemoglobin molecule. Heme is a porphyrin ring - an openwork and almost symmetrical organic molecule with a system of conjugated double bonds and four nitrogen atoms, which forms a complex with an iron atom.
Proteins containing heme, in this case are called cytochromes (the name comes from the Greek "chromos" - color, since heme has a color). The last of the cytochromes, with the help of the cytochrome oxidase enzyme (they are part of the third protein aggregate), donates electrons to the oxygen molecule (we remember that heme is able to bind oxygen), resulting in the formation of the O2- ion. When combined with protons, this ion forms a water molecule. (At the same time, the hydrogen balance is restored. We remember that protons were formed during the oxidation of NAD-H and FAD-H2, which in turn received hydrogen from organic substances in the Krebs cycle.))
Thus, it is as a result of electron transfer in the process of cellular respiration that oxygen is consumed and water is formed.
Why is all this necessary, you ask? The electron transport chain is arranged in such a way that the transfer of each electron along it is accompanied by the transfer of protons through the inner mitochondrial membrane from the inner space of the mitochondrion to the outer space (relative to the inner mitochondrial membrane). A proton is also released outside, which is formed during the oxidation of NAD-H. These processes go against the concentration gradient of hydrogen ions and, accordingly, against the electrostatic force and require the expenditure of energy, which, as it advances, gives up the electron. As a result, a pH difference (i.e., proton concentration) is formed inside and outside the inner membrane of the mitochondrion, and a difference in electrical potentials is formed on the two surfaces of the membrane - the inner surface of the membrane is negatively charged, and the outer one is positively charged. Actually, for the sake of this only such complex biochemistry is involved.
The electron transport chain is shown in the following figure.
Here, the proteins involved in the electron transport chain are depicted as compact white zones, FMN, FMNH2 are the oxidized and reduced form of flavin mononucleotide, Q, QH are the oxidized and reduced form of ubiquinone, FeS is ferrodoxin, various cytochromes are indicated by lowercase Latin letters.
What is this difference in acidity and potentials on both sides of the inner mitochondrial membrane for? There is another complex of two proteins, one might say, the main one in the entire system - ATP synthetase. This complex permeates the inner mitochondrial membrane and accounts for about 15% of the mass of all proteins of this membrane. It is designed in such a way that it passes protons one by one back from the outer space into the inner space of the mitochondria. This movement occurs along a concentration gradient and under the action of an electrostatic force. The energy of protons moving under the action of the potential energy difference is used to phosphorylate ADP with the formation of ATP.
(on the right is an electron micrograph of vesicles derived from the inner mitochondrial membrane, showing parts of ATP synthetase protruding into the interior)
This energy depends on the potential difference on the two sides of the membrane. It is generally accepted that it usually takes three protons to make one molecule of ATP. The number of protons pumped by the electron transport chain is also not precisely defined and may depend on many factors. It is now believed that the oxidation of one NAD-H molecule produces about 2.5 ATP molecules, and the oxidation of FAD-H2 produces about one and a half ATP molecules. (It is interesting that even 10 years ago it was believed that the energy gain from the oxidation of these proton carriers is 3 and 2 ATP molecules, respectively.) strict quantitative correspondence. In addition, the energy of the proton gradient is used by the mitochondria for other purposes, in particular, for the transport of "fuel" - anions, namely pyruvate and phosphates, into the mitochondria. Since the pH inside the mitochondria is elevated, the anions do not diffuse there on their own. Therefore, they are transported at the expense of special membrane proteins, which draw energy for this from the same source as ATP synthetase - due to protons “launched” back into the mitochondria.
Aerobic bacteria do not have mitochondria, and the difference in pH and potentials is created by the outer membrane of the cell, i.e., the cell as a whole plays the same role as eukaryotic mitochondria (glycolysis occurs in the cytoplasm, i.e., in the same place as the Krebs cycle, How is it different from eukaryotes? And in anaerobic bacteria, ATP synthetase, on the contrary, creates a proton gradient necessary for the cell for various biochemical purposes, due to ATP hydrolysis, that is, it works in the opposite direction.
The principle of oxidative phosphorylation remotely resembles a hydroelectric power plant, including its not very high efficiency - and here and there a certain energy carrier passes from a state with a higher potential energy to a state with a lower energy and at the same time does work. Only there the gravitational potential energy passes into mechanical and then into electrical, but here just Electric Energy passes into the energy of chemical bonds, but also through the mechanical energy of moving protons.
If a hole is made in the dam of a hydroelectric power station, then the water will flow out, and its potential energy will turn into heat without doing any useful work. The same can be done with mitochondria. There are certain substances that are soluble in the phospholipid membrane and are able to accept and donate a proton. Such substances can diffuse back and forth in the membrane and along the way carry protons along the concentration gradient. This movement will equalize the difference in electrical potential and pH without producing any mechanical work. This is called uncoupling of oxidation with phosphorylation. By the way, this effect, apparently, has a hormone thyroid gland, some amounts "bleed steam out of the boiler" without oxidative phosphorylation. It would seem that we are talking about some kind of sabotage that nullifies the useful work of the electron transport chain. However, the uncoupling of oxidation from phosphorylation is by no means useless. The energy stored on the inner membrane of the mitochondria cannot disappear without a trace, even if it did not go to any chemical work. She turns warm. It is in this way that thermogenesis is realized in the body - the production of heat. In addition to the heat released during the course of a variety of energy-wasting chemical processes, we are specially warmed by our mitochondria, also due to the energy generated by the electron transport chain during the oxidation of NAD-H. Thermogenesis is especially important for warm-blooded birds and mammals, but almost all organisms have it to some extent. It is curious to know that although our entire body from the inside has approximately the same and quite high temperature, heat in the body is released mainly by two organs - the heart and the liver.
Here is a very rough diagram of oxidative phosphorylation - electron transfer, conjugated transport of protons through the membrane and their reverse transport through ATP synthetase with conjugated ATP synthesis. This schematically shows three proteins involved in the electron transport chain, in fact there are many more.
ATP is produced in the mitochondria but is needed by the entire cell. However, the formed ATP cannot spontaneously penetrate from the mitochondria into the cytoplasm. For this, the mitochondrial membrane has a special protein - translocase, which produces the reaction of exchanging one ATP molecule from inside the mitochondrion for one ADP molecule outside the mitochondria, and it does this free of charge, that is, without energy expenditure.
The figure shows a diagram covering the entire process of glucose breakdown, including glycolysis, the Krebs cycle and oxidative phosphorylation:
Let's compare the economic efficiency of anaerobic and aerobic breakdown of 1 glucose molecule.
Under anaerobic conditions, the process ends with the formation of lactate and results in two ATP molecules (four formed, two spent).
Under aerobic conditions, we have the same two ATP molecules from glycolysis, plus two GTP molecules formed during the Krebs cycle, one for each of the two acetyl-co-A molecules formed from one glucose molecule. We also have 8 molecules of reduced NAD-H for each glucose molecule - two for the conversion of two pyruvate molecules into two molecules of acetyl-co-A, six during the Krebs cycle (again, for two molecules of acetyl-co-A). In addition, we have two molecules of reduced FAD-H2. It should be remembered that in the course of glycolysis, with additional phosphorylation, two more NAD-H molecules were restored. It would also be good to drag them into the mitochondria and exchange them for ATP, but there is no such mechanism. Instead, there is a kind of exchange of the reduced state of the NAD-H molecule outside the mitochondria for the reduced state of the FAD-H2 molecule, carried out through the reduction of dihydroxyacetone phosphate (already familiar to us from glycolysis) to glycerol-3-phosphate outside the mitochondria and the reverse process inside the mitochondrion. These small molecules are able to "free" to penetrate into the mitochondria and back. However, there is some energy loss. The FAD-H molecule "costs" 1.5 ATP molecules. (It should be added that in the heart and liver there is a mechanism of "equivalent" exchange, when the oxidation of NAD-H outside the inner mitochondrial membrane is exchanged for the reduction of NAD + inside.)
A direct calculation of the energy received is difficult because the number of protons pumped during the movement of electrons, the number of protons necessary for the synthesis of one ATP, the magnitude of the proton gradient itself are not completely constant values and depend on the concentration of protons, ATP and ADP and other substances; moreover, the energy of the proton gradient is spent on many purposes. In general, it turns out that the aerobic breakdown of one glucose molecule produces about 30 ATP molecules, that is, it is 15 times more efficient than glycolysis. This is what the atmosphere of free oxygen created by life means for the efficiency of biological processes.
So, using glucose as an example, we looked at how we oxidize organic substances to carbon dioxide and water in order to obtain energy. The principal thing here is that the formation of carbon dioxide from organic carbon occurs in one part of this complex process, and the formation of water - due to the combination of released hydrogen with free oxygen - in another part. The formation of ATP - the universal energy carrier - occurs mainly in this second part. These processes go on constantly and at high speed in any cell of our body. Many other complex processes take place there, but many of them have a common part, as a rule, it is acetyl-coA and the Krebs cycle.
However, it should be noted that in the course of oxidative phosphorylation in macroergic bonds of ATP, only about 40% of the calculated energy is utilized, which should be released from the combination of hydrogen with oxygen. The efficiency is not very high, but this is a payment for the fact that energy enters the cell in small portions, stored in those energy carriers that it is able to process. Only in this form can it, in principle, be used by living beings. The process of oxidation of organic molecules in the process of cellular respiration is divided into many steps. The carbon chain of glucose does not break down into carbon atoms to immediately bond with oxygen, as happens during combustion. Instead, we have seen how carbon atoms are constantly rearranged in molecules containing 3 to 6 of these atoms, and carbon dioxide is released during some of these rearrangements. This is due to the enzymatic nature of all occurring reactions - it is “more convenient” for enzymes to work with organic molecules of such sizes. Accordingly, for the complete oxidation of carbohydrates to carbon dioxide, a chain of intermediary substances was required, which had to be constantly regenerated - this is what the Krebs cycle exists for. This "invention" is also convenient because its elements can participate in a variety of processes occurring in the cell. Thus, through the Krebs cycle, it is possible to “redirect resources” in the right direction and thereby regulate the entire “cell economy”. The Krebs cycle is not the only cyclic biochemical process.
Similar information.
Plants absorb carbon dioxide (CO2) from environment and using solar or other energy to convert it into glucose, animals consume glucose, and then release carbon dioxide into the atmosphere.
In Israel, a team of researchers from the Weizmann Institute of Science has found a way to "reprogram" living bacteria to consume CO2 from the environment and produce glucose, which is essential for all bodily functions.
evolved
bacteria still release carbon dioxide
This ability, called carbon fixation, could help solve food problems as the world's population grows and natural resources shrink.
The scientists started by enabling a metabolic pathway for carbon fixation and glucose production in the bacterium E. coli (E. coli), which normally consumes sugar and releases carbon dioxide. The first attempt was unsuccessful - the bacterium produced the enzymes necessary for carbon fixation, but could not process CO 2 into sugar.
Then the researchers decided to do otherwise. They made special tanks that contained bacteria, and gradually developed the ability of living organisms to absorb carbon dioxide. By the third month of the experiment, the bacteria used CO 2 to create a significant portion of their body mass, including the glucose necessary for cell formation.
These evolved bacteria still emit carbon dioxide, but the team of researchers believe that their work laid the foundation for the creation of microorganisms or cultures with high carbon fixation, which, by consuming CO 2 from the atmosphere, would convert it into energy storage.
Posts from This Journal by “science” Tag
Stephen Hawking: "There was no need for God, and God did not have time"
Stephen Hawking “For centuries it was thought that people like me, that is, people with disabilities, were cursed by God. I think I am someone...
Fathers of Israeli high-tech
As the most outstanding physicist of the 20th century, Albert Einstein argued with the great mathematician John von Neumann and the brilliant chemist and politician...
Detaly.co.il: New hominin species changes the paradigm of human evolutionAn unknown species of hominid has been discovered in the Philippines, an international team of scientists reported in the journal Nature. They lived on the island of Luzon and...
NIELS BOHR'S NUCLEAR FORCE
His grandfather was a major Jewish banker, his father was a world-famous professor of physiology. At the age of 28, he himself created the first quantum ...
Albert Einstein and his connection with Israeli science
March 14 marks the 140th anniversary of the birth of the brilliant physicist, Nobel laureate Albert Einstein, whose famous theory ...
Legend #1Cell phones equipped with its semiconductors. Players, computers and barcode scanners are his lasers. The other day at the age of 88…
As a result of photosynthesis, as you know, glucose C 6 H 12 O 6 is formed from carbon dioxide and water in green plants. It belongs to a class of organic substances called carbohydrates.
Carbohydrates (saccharides) are the end products of photosynthesis and are the starting materials for the biosynthesis of other organic compounds.
When they are formed, solar energy is accumulated, which is converted into chemical energy and serves as a source for biosynthesis processes that are endothermic (remember what this means).
Carbohydrates are found in the cells of all living organisms. AT animal cage the content of carbohydrates is 1-2%, and in vegetable it reaches in some cases 85-90% of the mass of dry matter of the cell.
Carbohydrates are named after the elemental composition of their molecules. These compounds contain only chemical elements: carbon, hydrogen and oxygen, and hydrogen and oxygen are in them, as a rule, in the same ratio as in the water molecule, -2:1. Hence the name of the class of substances. The composition of most carbohydrates corresponds to the general formula C n (H 2 O) m
Many carbohydrates contain fruits and vegetables. So, beet or cane sugar is a carbohydrate. Honey is almost entirely composed of carbohydrates. They include different kinds starch, which are part of potatoes and cereals (wheat, rice, corn, rye, etc.) (Fig. 64).
Rice. 64.
Starch Plants:
1 - sweet potato; 2 - rice; 3 - wheat; 4 - earthen pear (Jerusalem artichoke); 5 - corn; 6 - potatoes
Cellulose is a carbohydrate that is the main part of wood. Widely used in medicine, cotton wool and gauze are almost entirely composed of cellulose. Paper is almost pure cellulose.
Carbohydrates are used by humans directly (Fig. 65), as well as for the synthesis of a number medicinal substances(gluconic acid, ascorbic acid, or vitamin C), explosives (cellulose nitrate, or pyroxylin), artificial fibers (viscose, cellulose acetate, or acetate fiber) and other much needed in everyday life, medicine, agriculture and the technique of substances and materials (see Fig. 3).
Rice. 65.
Carbohydrates in human life:
1-3 - food; 4.5 - fibers and fabrics (cotton 4, linen 5); 6 - wood products; 7.8 - paper and paper products
In accordance with the peculiarities of their structure and properties, carbohydrates are divided into three groups: monosaccharides, disalarides and polysaccharides (Scheme 1).
Scheme 1
Classification of carbohydrates
Let's start our acquaintance with individual groups of carbohydrates with monosaccharides.
The most important are pentoses (the molecules of these monosaccharides contain five carbon atoms) and hexoses (contain six carbon atoms).
Among pentoses, it is necessary to name ribose C 5 H 10 O 5 and deoxyribose C 5 H 10 O 4 (this is a ribose in which one oxygen atom is “removed” from the molecule). It is easy to see that the formula for deoxyribose does not correspond to the general formula for carbohydrates.
Ribose and deoxyribose play an important role in the life of organisms. They, respectively, are part of RNA and DNA. Ribose is also part of ATP, the most important energy substance of the cell, which ensures the metabolism and energy in it. It flows according to the scheme
Glucose C 6 H 12 O 6 is the most abundant and by far the most important monosaccharide, hexose. It is found in grape juice (hence the trivial name for glucose - grape sugar), other berries and fruits, is a structural link of sucrose, cellulose, starch. Normal human blood contains about 0.1% glucose.
Glucose is a white crystalline substance with a sweet taste, highly soluble in water.
Glucose can form macromolecules of starch, cellulose and other polysaccharides.
According to the chemical structure, glucose belongs to polyhydric alcohols, since it contains five hydroxyl groups -OH (remember the monohydric ethyl alcohol C 2 H 5 OH and the trihydric alcohol glycerol
In addition to hydroxyl groups, the glucose molecule also contains a carbonyl group. The structural formula of glucose can be conditionally written as follows:
The proposed formula does not reflect the true structure of the glucose molecule. What is it really like?
Due to the free rotation of the carbon chain of relatively simple carbon-carbon bonds, in aqueous solution the aldehyde group is close to the hydroxyl at the 5th carbon atom. As a result of intramolecular addition, two possible cyclic forms of glucose are formed. They are a six-membered cycle containing an oxygen atom. There are five hydroxyl groups in the cyclic forms of glucose, but the hydroxyl at C(1), formed from the aldehyde group of the chain form, has special properties.
The cyclic forms of carbohydrates are conveniently represented by promising Haworth formulas (Fig. 66). The cycle is conditionally considered flat and projected onto the sheet plane at a certain angle, with the oxygen atom being depicted at the maximum distance to the right. The nearest part of the ring is depicted from below and is sometimes distinguished by a thicker line. Atoms or groups of atoms in Haworth's formulas are located above and below the plane of the cycle.
Rice. 66.
Interconversions of cyclic and linear forms of glucose molecules
The cyclic forms of glucose differ in the mutual position of the hydroxyl group at the first and last carbon atoms. If these groups are in different sides cycle, such an isomer is called α-D-glucose if on one side is β-D-glucose (or simply α- or β-glucose).
In an aqueous solution of glucose, all three forms are present in equilibrium: a chain form and two cyclic forms. In the solid state, glucose can exist in one of two cyclic forms.
Glucose, like a polyhydric alcohol, as you know, interacts with a fresh precipitate of copper (II) hydroxide. In this case, the precipitate dissolves and a bright blue solution of copper (II) saccharate is formed.
Glucose also provides one of beautiful reactions in chemistry - the reaction of the "silver mirror" with an ammonia solution of silver oxide. As you know from § 11, this reaction is qualitative for aldehydes. A simplified equation for this reaction can be written as follows:
Substances that exhibit the characteristic properties of two different classes of organic compounds have a dual function. Glucose is both a polyhydric alcohol and an aldehyde, i.e., an aldehyde alcohol.
As an aldehyde, glucose undergoes a hydrogenation reaction:
For glucose, fermentation reactions are also characteristic (the transformation of some organic compounds into others, which are carried out under the action of enzymes produced by microorganisms).
The most important reactions are:
a) lactic acid fermentation:
(this reaction occurs in the process of sauerkraut, silage feed);
b) alcoholic fermentation:
(This reaction is widely used for the production of ethyl alcohol and in baking). The scheme for obtaining ethyl alcohol from glucose based on the hydrolysis of starch is shown in Figure 67.
Rice. 67.
Scheme for the production of alcohol from starch
Glucose is the main source of energy in the cell. That is why it is widely used for medicinal purposes (used orally or administered intravenously to weakened patients).
Glucose is widely used. She is the starting material for obtaining various compounds: ethyl alcohol, lactic acid, etc. (Fig. 68).
Rice, 68.
Application of glucose:
1 - production of vitamin C (ascorbic acid); 2.3 - food industry; 4 - obtaining sorbitol
AT Food Industry it is used as a substitute for sucrose, although it is slightly less sweet. For this purpose, molasses is usually used - a syrupy mass obtained by incomplete hydrolysis of starch.
When glucose is added to sucrose, it prevents its crystallization and is therefore used in the confectionery industry to produce caramel, marmalade, fudge, etc.
As a sugar substitute for people with diabetes, use the glucose recovery product - sorbitol hexatomic alcohol.
The isomer of glucose is another monosaccharide - fructose C 6 H 12 O 6, which is also a substance with a dual function, but already a keto alcohol. Its formula can be represented as follows:
Fructose is called fruit sugar. It, along with glucose, is found in the juice of berries and fruits, and makes up the bulk of bee honey (Fig. 69).
Rice. 69.
Fructose in nature: honey, fruits, berries
New words and concepts
- Monosaccharides.
- Glucose is an aldehyde alcohol.
- Chemical properties of glucose: interaction with copper (II) hydroxide, "silver mirror" reaction, hydrogenation, fermentation reactions.
- The use of glucose.
- Fructose.
Questions and tasks
- What substances are called carbohydrates? Why? How does this class of organic compounds illustrate the idea of the relationship between organic and inorganic substances, i.e., the unity of the chemical organization of the material world?
- What are monosaccharides? What groups are they divided into?
- What features are the basis for the classification of all carbohydrates and which one is the basis for the classification of monosaccharides?
- Why is glucose classified as a substance with a dual function? Confirm this thesis by considering the chemical properties of glucose.
- What properties of glucose find practical application? Illustrate your answer with the corresponding reaction equations.
- A group of atoms that determines the most characteristic properties of a substance and its belonging to a certain class of organic compounds is called functional. The paragraph dealt with four functional groups. What?
- In addition to glucose and fructose, which have a dual function, another substance with such a function was mentioned in the paragraph. What is it called? What formula does it have? Form a dual name based on the dual function of this substance.
- Write the reaction equations that can be used to carry out the following transformations:
a) carbon dioxide → glucose → sorbitol;
b) glucose → gluconic acid → sodium gluconate (sodium salt of gluconic acid);
c) glucose → ethyl alcohol → ethylene and lactic acid.
- Calculate the volume of carbon dioxide (n.a.) that can be formed during alcoholic fermentation of a solution containing 720 g of glucose. Calculate the mass of 96% ethyl alcohol that can be obtained as a result of this reaction with a product yield equal to 85% of the theoretically possible.
- Monosaccharides include ribose C 5 H 10 O 5 and deoxyribose C 5 H 10 O 4 . Explain whether the formula of the last substance obeys the general formula of carbohydrates.
Glucose translated from Greek means "sweet". In nature, in large quantities, it is found in the juices of berries and fruits, including grape juice, which is why it is popularly called "wine sugar".
Discovery history
Glucose was discovered at the beginning of the 19th century by the English physician, chemist and philosopher William Prout. This substance gained wide popularity after Henri Braccono extracted it from sawdust in 1819.
Physical Properties
Glucose is a colorless crystalline powder with a sweet taste. It is highly soluble in water, concentrated sulfuric acid, and Schweitzer's reagent.
The structure of the molecule
Like all monosaccharides, glucose is a heterofunctional compound (the molecule contains several hydroxyl and one carboxyl group). In the case of glucose, the carboxyl group is an aldehyde.
The general formula for glucose is C6H12O6. The molecules of this substance have a cyclic structure and two spatial isomers of alpha and beta forms. In the solid state, the alpha form predominates almost 100%. In solution, the beta form is more stable (it occupies approximately 60%). Glucose is the end product of the hydrolysis of all poly- and disaccharides, that is, the production of glucose occurs in the vast majority of cases in this way.
Getting a substance
In nature, glucose is formed in plants as a result of photosynthesis. Consider industrial and laboratory methods for obtaining glucose. In the laboratory, this substance is the result of aldol condensation. In industry, the most common way is to obtain glucose from starch.
Starch is a polysaccharide, the monoparts of which are glucose molecules. That is, to obtain it, it is necessary to decompose the polysaccharide into monoparts. How is this process carried out?
Obtaining glucose from starch begins with the fact that the starch is placed in a container of water and mixed (starch milk). Bring another container of water to a boil. It is worth noting that boiling water should be twice as much as starched milk. In order for the reaction to produce glucose to go to completion, a catalyst is needed. In this case, it is salt or The calculated amount is added to a container of boiling water. Then the starch milk is slowly poured in. In this process, it is very important not to get a paste, if nevertheless it is formed, boiling should be continued until it disappears completely. On average, boiling takes an hour and a half. In order to be sure that the starch is completely hydrolyzed, it is necessary to carry out a qualitative reaction. Iodine is added to the selected sample. If the liquid becomes blue in color, then the hydrolysis is not completed, but if it becomes brown or red-brown, then there is no more starch in the solution. But this solution contains not only glucose, it was obtained with the help of a catalyst, which means that acid also has a place to be. How to remove acid? The answer is simple: by neutralizing with pure chalk and finely crushed porcelain.
Neutralization is checked Next, the resulting solution is filtered. The point is small: the resulting colorless liquid should be evaporated. The formed crystals are our end result. Now consider the production of glucose from starch (reaction).
The chemical essence of the process
This equation for obtaining glucose is presented before the intermediate product - maltose. Maltose is a disaccharide consisting of two glucose molecules. It is clearly seen that the methods for obtaining glucose from starch and from maltose are the same. That is, in continuation of the reaction, we can put the following equation.
In conclusion, it is worth summarizing the necessary conditions in order to successfully extract glucose from starch.
The necessary conditions
- catalyst (hydrochloric or sulfuric acid);
- temperature (at least 100 degrees);
- pressure (atmospheric is enough, but increasing pressure speeds up the process).
This method is the simplest, with a large yield of the final product and minimal energy costs. But he's not the only one. Glucose is also obtained from cellulose.
Preparation from cellulose
The essence of the process almost completely corresponds to the previous reaction.
The preparation of glucose (formula) from cellulose is given. In fact, this process is much more complicated and energy-intensive. So, the reaction product is waste from the wood processing industry, crushed to a fraction, the particle size of which is 1.1 - 1.6 mm. This product is treated first with acetic acid, then with hydrogen peroxide, then with sulfuric acid at a temperature of at least 110 degrees and a hydromodulus of 5. The duration of this process is 3-5 hours. Then, for two hours, hydrolysis takes place with sulfuric acid at room temperature and hydromodulus 4-5. This is followed by dilution with water and inversion for about an hour and a half.
Quantification methods
Having considered all the methods for obtaining glucose, methods for its quantitative determination should be studied. There are situations when technological process only a solution containing glucose should participate, that is, the process of evaporating the liquid until crystals are obtained is superfluous. Then the question arises, how to determine what concentration of a given substance in a solution. The resulting amount of glucose in solution is determined by spectrophotometric, polarimetric and chromatographic methods. There is also a more specific method of determination - enzymatic (using the enzyme glucosidase). In this case, the count goes already products of this enzyme.
Application of glucose
In medicine, glucose is used for intoxication (it can be both food poisoning and infection activity). In this case, the glucose solution is administered intravenously using a dropper. This means that in pharmacy, glucose is a universal antioxidant. This substance also plays an important role in the detection and diagnosis diabetes. Here glucose acts as a stress test.
In the food industry and cooking, glucose occupies a very important place. Separately, the role of glucose in winemaking, beer and moonshine production should be indicated. We are talking about such a method as obtaining ethanol. Let us consider this process in detail.
Getting alcohol
Alcohol production technology has two stages: fermentation and distillation. Fermentation, in turn, is carried out with the help of bacteria. In biotechnology, cultures of microorganisms have long been bred, which allow you to get the maximum yield of alcohol with the minimum amount of time spent. In everyday life, ordinary table yeast can be used as reaction assistants.
First of all, glucose is diluted in water. The microorganisms used are diluted in another container. Further, the resulting liquids are mixed, shaken and placed in a container with This tube is connected to another one (U-shaped). In the middle of the second tube is poured. The end of the tube is closed with a rubber stopper with a hollow glass rod having a drawn end.
This container is placed in a thermostat at a temperature of 25-27 degrees for four days. Turbidity will be observed in a tube with lime water, which indicates that carbon dioxide has reacted with it. As soon as carbon dioxide ceases to be released, fermentation can be considered finished. Next comes the distillation step. In the laboratory for the distillation of alcohol, reflux condensers are used - devices in which a cold water, thereby cooling the resulting gas and converting it back into a liquid.
On the this stage the liquid that is in our container should be heated to 85-90 degrees. Thus, the alcohol will evaporate, but the water will not be brought to a boil.
The mechanism for obtaining alcohol
Consider the production of alcohol from glucose in the reaction equation: C6H12O6 \u003d 2C2H5OH + 2CO2.
So, it can be noted that the mechanism for producing ethanol from glucose is very simple. Moreover, it has been known to mankind for many centuries, and brought almost to perfection.
The value of glucose in human life
So, having a certain idea about this substance, its physical and chemical properties, use in different areas industry, we can conclude what glucose is. Obtaining it from polysaccharides already gives an understanding that, being the main component of all sugars, glucose is an indispensable source of energy for humans. As a result of metabolism, adenosine triphosphoric acid is formed from this substance, which is converted into a unit of energy.
But not all glucose that enters the human body goes to replenish energy. In the waking state, a person converts only 50 percent of the received glucose into ATP. The rest is converted to glycogen and stored in the liver. Glycogen breaks down over time, thereby regulating blood sugar levels. Quantitatively, the content of this substance in the body is a direct indicator of its health. The hormonal functioning of all systems depends on the amount of sugar in the blood. Therefore, it is worth remembering that excessive use of this substance can lead to serious consequences.
Glucose at first glance is a simple and understandable substance. Even from the point of view of chemistry, its molecules have a fairly simple structure, and Chemical properties understandable and familiar in everyday life. But, despite this, glucose is of great importance both for the person himself and for all spheres of his life.