Identify the wrong statement with reference to the gene ‘I’ that controls ABO blood groups.
Identify the wrong statement with reference to the gene ‘I’ that controls ABO blood groups.
A person will have only two of the three alleles.
When IA and IB are present together, they express same type of sugar.
Allele ‘i’ does not produce any sugar
The gene (I) has three alleles.
Solution
For the ABO system of blood groups, allele IA produces N acetylgalactosamyl transferase enzyme which recognizes H antigen present in RBC membrane and adds N-acetylgalactosamine to sugar part of H antigen to form A antigen. The allele IB produces galactosyl transferase enzyme which adds galactose o the sugar part of H antigen to form B antigen. Allele 'i' does not produce any sugar or antigen. When both IA and IB are present in a person, both enzymes thus both antigens A and B are produced. This is because of co-dominance. These antigens determine the type of AB blood group.