Question

A child has blood group O. If the father has blood group A and mother

blood group B, work out the genotypes of the parents and the possible

genotypes of the other offsprings.

Answer 1

The blood group characteristic in humans is controlled by three set of alleles, namely, I^A, I^B, and i. The alleles, I^A and I^B, are equally dominant whereas allele, i, is recessive to the other alleles. The individuals with genotype, I^A I^A and I^A i, have blood group A whereas the individuals with genotype, I^B I^B and I^B i, have blood group B. The persons with genotype I^A I^B have blood group AB while those with blood group O have genotype ii.

Hence, if the father has blood group A and mother has blood group B, then the possible genotype of the parents will be

Father Mother

I^A I^A or I^A i I^B I^B or I^B i

A cross between homozygous parents will produce progeny with AB blood group.

A cross between heterozygous parents will produce progenies with AB blood group (I^AI^B) and O blood group (ii).