Question

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You will use  A, B, and O for these questions to represent the alleles in this example.

The ABO blood system works in Mendelian fashion, but it has three possible alleles at one locus (A, B, and O alleles). Each person can have only two of those alleles in their genotype. A and B are both dominant (and can be co-dominant) and O is recessive to both A and B. So, for example, if you have B blood type, your genotype could be either BB or BO — both of these genotypes would produce B phenotypes. If your phenotype is AB blood type, your genotype is AB.

Given the following scenario determine the genotypes of all these individuals. (Hint: What can the offspring tell you about the parents?)

You have a mother who has two children. There are two men who might need to pay child support; we need to figure out which man owes. Who is the father of these two children?

Mother: blood type A

Child 1: blood type O

Child 2: blood type A

Possible father 1: blood type A

Possible father 2: blood type O

1. List all possible genotypes for each of these individuals (mother, 2 children, 2 men).
2. Based on this information, is it possible to exclude either of these men as being the father? Why or why not?

Answer 1

ANSWER :

1. List of the all possible genotypes for each individuals :-

Individual & blood type	Possible genotypes
Mother (blood group A)	IO IA or IA IA
Child 1 (blood group O)	IO IO
Child (blood type A)	IO IA or IA IA
Possible father 1 (blood type A)	IO IA or IA IA
Possible father 2 (blood type O)	IO IO

2. Both the men, whose genotypes A and O respectively might be a father of children because when crossed with mother of blood type A, would able to produce all the combination of allelic genotypes to both the children (IO IA or IA IA, and IO IO).