Invisible, indispensable
The closer the spring, the louder the complaints of lack of vitamins. However, it is still unclear whether to hope for their miraculous powers. The cold, bad mood, dry skin — as it turned out that several small molecules responsible for all our troubles?
Invisible heroes, who are they?
If vitamins could speak, the first thing they’d ask who and what brought them together. These substances are not similar in structure or in origin or chemical properties. Unites them only one thing — we all need them bad. To replace them does not work, counterparts they have, and by itself our body to produce them can not (with rare exceptions). Thus a serious deficiency of each vitamin (beriberi) disables multiple organ systems. There are two reasons.
First, most of the vitamin is not one substance but a family of close relatives. For example, vitamin D there are five types (D1-D5), and under the code name “vitamin a” hiding retinol, retinal, retinoic acid and the group of carotenoids.
Vitamins-relatives differ from each other by several atoms or chemical groups. Typically, food comes to us any one member of the family, and then the cells transform to other related substances.
However, even very close in structure of the molecule can have fundamentally different functions. Retinal (not to be confused with retinol!) and retinoic acid is similar to all but one atom of hydrogen. But the first works in retinal cells by absorbing photons, and the second forced to develop the foetus.
Therefore, when the body ends in some one vitamin that played an entire family tragedy — not enough resources for the production of all his relatives, and the effect of this impact on many parts of the body.
Secondly, the vitamins, generally a lot of work that is distributed throughout the body. They are often intermediates in metabolism, and when these units appear in many different types of cells simultaneously stop multiple processes.
The roles and responsibilities of the vitamins can be divided into two groups.
Apprentice
Most of the vitamins (all except vitamin D and retinoic acid) work on the principle of “bring-bring”, shifting between molecules and small chemical groups, electrons, protons or photons. Sometimes it is necessary for energy transfer — thus, the retinal (a relative of vitamin A) catches the photon gives its energy to rodopsin proteins in the retinal cells. Therefore, in the absence of occurs night blindness — much worse night, black-and-white vision.
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Sometimes vitamins protect cells from free radicals — aggressive molecules that have one electron more or less than you need. Vitamin E heroically takes on extra electrons, and passes someone will not harm them. In the absence of radicals accumulates more and they attack proteins and fats in cells — develops oxidative stress, causing cell death. Retinal can also pick up extra electrons, and vitamin C acts on the contrary — shares its electrons with those who lack them. They do not give rise to stress and are antioxidants.
Finally, many vitamins serve as coenzymes — apprentices that help the enzymes present masters. Enzymes create the conditions in which chemical reactions take place faster than in conventional solution: seize and hold substances that must react, and have them next to each other so that chemical bonds had to just readjust. Sometimes in these reactions are released individual protons, electrons, or groups of several atoms. At this point in the case involving coenzymes. They are taking vacant pieces of molecules and atoms, so they do not enter into any unwanted reaction. Then they can transfer them to other place cells, or transfer to another chemical reaction. This is how all b vitamins, and sometimes S.
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The work of these apprentices seem insignificant? Let’s imagine what will happen if they will not. Let our body — is the city in which there are boys. They are able to perform only one simple job (but she one can not do) — to file the nails. If some one carpenter will have a nail, the city will not notice the trick. But if every time anyone in the city will need to hammer in a nail, a boy with a nail will not close, then gradually all work in the city will rise — no one will be able to fix old buildings and build new ones.
Take vitamin B1 — it takes two-carbon fragments of molecules. This is necessary, for example, for breaking down glucose and create the myelin sheaths of nerve fibers, as well as neurotransmitters that transmit signals between neurons. For example, the person has ceased to vitamin B1. Glucose became more difficult to break down, cells don’t have enough power, the signals between neurons are transmitted poorly (not enough neurotransmitters), and signals from the brain to other parts of the body are transmitted very slowly (not enough shells). The result is known to us as the disease beriberi cachexia, a person is difficult to control the parts of the body, mental activity is inhibited.
Messengers
Vitamin D and retinoic acid work very differently. They carry no parts of molecules, and signals. Since both of these substances are fat soluble, they easily penetrate through the cell membrane (composed of fat), and then the kernel. This allows them to contact the receptors not only on the surfaces of cells, but also inside. Which means they can directly affect the activity of genes in the nucleus. And, as any other signal molecules, they have a variety of targets. Under the action of vitamin D, some cells divide, others synthesize neurotrophic factors (thereby stimulating growth of tissue), and others — absorbed calcium in the intestine.