Question

Gene is heterozygous type B and Molly is homozygous B blood. What are all the possible blood types of their future children? Write it in genotype and phenotype percentages

Answer 1

All children of Gene and Molly will have B blood group only.

Explanation:

Gene has heterozygous type B blood. The genotype of Gene will be `I^B I^b`.
Molly has homozygous type B blood. The genotype of Molly will be `I^B I^B`.

Gametes contributed by Gene having dominant allele (`I^B`), and recessive allele (b) will be in the ratio of 1:1.

All gametes contributed by Molly will carry dominant allele (`I^B`).

Considering the possible combinations of gametes contributed by the parents to form oospore (zygote), all children will carry one dominant allele (`I^B`).

All the children thus will be phenotypically similar and will have B blood group, because dominant allele can express in phenotype whether in the homozygous or heterozygous state.

However, 50% of children will be homozygous (`I^B I^B`), and 50% will be heterozygous (`I^B I^b`). Thus the ratio of `I^B I^B` (homozygous) and heterozygous (`I^B I^b`) will be in the ratio of 1;1. The genotypic ratio is thus 1:1.

A punnet square for the same is given below