In: Biology
Andrea has AB+ blood type
Candidate 1: A-
Candidate 2: B-
Candidate 3: AB+
June which is her mom has B- blood type.
Why does this test NOT prove that a given person is Andrea's father?
and what additional test can be done to show that a candidate is indeed Andrea's father?
Condidate3: AB+
ABO blood group is a multiple allele phenomenon , in which A and B are codominant , O is recessive to both A and B allele. Rh positive is dominant to Rh negative. June is B-, it means she has either two B alleles or one B allele and one O allele . But she should be heterozygous Rh-. Andrea has AB+ genotype. It means she has received one B alleles from her mother and one A allele from her father. But her mother is Rh- allele so Andrea will be Rh+ only when she will receive Rh+ allele from her father.
Candidate A and Candidate B both have only Rh- allele (homozygous Rh-), so they cannot be Andrea's father.
AB+ candidate may be her father if he is homozygous Rh+. So additional test has to e performed to determine Candidate 3 is homozygous Rh+ or heterozygous Rh+. If he is homozygous Rh+, he may be Andrea's father. But if he is heterozygous Rh+, then he must give Rh+ allele to Andrea. So there. is 50 % chance