WOULD YOU PLEASE EXPLAIN ABOUT THE MECHANISM OF BLOOD GROUP?

Asked by  | 14th Apr, 2013, 12:32: PM

Expert Answer:

This mechanism of inheritance in blood groups is multiple allelism  where three different alleles IA, IB and i control the four phenotypes of blood groups. However, out of these or the same allele in duplicate represent to any of the four blood groups.

Explanation : The red blood cell membrane has sugar polymers that protrude from its surface and the structure of the kind of sugar is controlled by the gene. The gene I has has three alleles IA, IB and i. The alleles IA and IB produce a slightly different form of the sugar while allele i does  not produce any sugar. The humans are diploid organism, each person possesses any two of the three I gene alleles. IA and IB are completely dominant over i. When IA and IB are present together they both express their own types of sugars. Hence red blood cells have A and B types of sugars. Since there are three different alleles, there are six different combinations of these three alleles that are possible a total of six different genotypes of the human ABO blood types.

Phenotypes

Alleles

AB – blood group

IAIB

O – blood group

ii

A – blood group

IAIB or IAi

B – blood group

IBIB or IBi

 During blood transfusion, a person is given blood having the same blood group otherwise there will be clumping and clotting of blood in the blood vessels and the patient will suffer from unavailability of oxygen. Suppose, a person having blood A is given blood with blood group B, will show clumping as the blood with blood group A will produce antibodies against blood group B.

Answered by Meghna Thapar | 15th Apr, 2013, 12:54: PM

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