Sasha thinks she may have been adopted She has blood type O

Sasha thinks she may have been adopted. She has blood type O, but mother has AB and her father has B blood type. Based on what we\'ve discussed in class, is it possible for Sasha\'a parents to have an O blood type child? Justify and explain your answer, give the genotype of Sasha and both of her parents. It is.

Solution

The O allele for blood type, is recessive to both the A and B allele and both the alleles A and B are co dominant, hence based on this fact Sasha parents when having the blood type AB and B have the genotypes AB and BO and for Sasha to have the O type blood she has to be homozygous for O allele as it is recessive to both A and B type; hence it is not possible as only one of the parents has the O allele and homozygosity cannot be achieved in the offspring i.e. Sasha.