It is Impossible to imagine modern medicine without such a simple method of treatment, like a blood transfusion. At the dawn of this technique, the doctors just pumped the fluid from one patient to another, not thinking about the consequences. Follow-up of patients allowed us to conclude that not all blood is suitable for transfusion. It was the introduction to the discovery of blood groups.
Multiple allelism – the existence of more than two variants in the same gene. It acts as a means of natural selection, that is, prevents the fusion of the sexual cells of organisms that cannot have viable offspring.
This explains the sterility of certain plants and animals, as well as the impossibility of the emergence of “children” in animals of different species. The variety of signs is also called "multiple allelism". Examples of this condition: different eye color or coat color, shape of ears or nose. But the same factor influences what blood group in humans.
Multiple allelism has certain laws:
- any gene can have more than two alleles;
- a variant of the gene can occur due to direct or reverse mutation of the other allele, and due to the changes “wild” gene;
in the organism with a diploid set of chromosomes can contain two different alleles;
- the alleles are dominant-recessive relationship between them;
- inheritance of alleles that obey the laws of Gregor Mendel.
Multiple allelism – is one of the manifestations of the variability of the genetic material of living organisms. One example of such variation can be called the inheritance of blood groups AB0.
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This system has certain characteristics:
- there are three alleles of the gene I – And In and 0;
- this gene is located in the ninth chromosome.
- the alleles A and b are dominant over 0, but between them they are equal;
- according to Mendel's laws, dominant genes manifest themselves both in Homo-and heterozygous organism, only in homozygous recessive for this trait.
Different combinations of alleles gives four blood groups: 0, A, b, and AB. They differ in the antigens (agglutinogens) presented on the surface of red blood cells. At the same time in the liquid portion of blood constantly circulating agglutinins. This specific antibodies that do not coincide with the agglutinogens.
The Phenomenon of multiple allelism provides a variety of phenotypic manifestation of this trait in humans. Blood is a good example of norm of reaction, as it does not change under the influence of any factors throughout life.
Multiple allelism – gene mutation that persistiruut in the population. One of the proteins that is subject to mutation, is the RH factor. This protein is inherited by a dominant type. By blood transfusion or pregnancy may occur in RH incompatibility. In this case, the blood begins to clot and develops DIC.
The mother's Blood and the fetus passes through the villi and is not mixed. If during the first pregnancy in RH-negative mother develops RH-positive baby, during childbirth his blood ExpressionEngine antigens can get into the vascular system women and cause allergic reactions of the delayed type. That is, the antibodies will accumulate in the body, but before re-pregnancy did not show. If the second child is also RH positive, there is a conflict between antibodies and antigens. This ultimately can lead to death of the fetus.
Multiple allelism – it is a manifestation of the same gene in different physiological ways. There are not only agglutinogens A, b and 0. Scientists have isolated more than two hundred agglutinogens, combined into twenty groups. This leads to the uniqueness of blood every single person on earth.
The Difference between these groups of systems АВ0 that plasma not agglutinins. The most important are agglutinogens, Rh, MN, S, P, A, Levis, Duppi, Kell, Kidd, and others. Blood various combinations of these antigens.
Fortunately, with a single blood transfusion makes no sense to consider all of these protein molecules, as they will not cause significant generalized allergic reactions. However, with frequent transfusions is not recommended to use blood of the same donor.
As we already know, in the human genotype is always present the phenomenon of multiple allelism. Blood group antigens are represented by A and b, the appearance of which is due to the presence of the gene I. They consist of protein and carbohydrates. The specificity of each antigen is determined by terminal fragment of a carbohydrate chain.
For the formation of antigens A and b needed N-substance, for which the responsible gene N. This structure is not an antigen, as have all the people on the membranes of red blood cells. In people with first blood is only a substance, but no antigens A and B....
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Alin Trodden - author of the article, editor
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