Question

This problem refers to the MN and ABO loci mentioned in class. It also refers to the Rh locus, which is responsible for the positive/negative part of the blood type. The Rh allele is dominant to the Rh- allele at this locus. Select all couples who could be the parents of the child below based on the phenotypes at these three loci. If none of these couples could be the parents of this child, select "None of These". child: MN, A Select one or more: Mother Type M, A and Father Type N, B- Mother Type MN, AB- and Father Type M, O- Mother Type MN, B and Father Type N, O Mother Type MN, O and Father Type MN, A- None of These

Answer 1

Answer:

1) Mother Type M, A and Father Type N

4) Mother Type MN, O and Father Type MN, A-

Explanation:

We have three loci in this problem with different alleles possible:

M/N alleles are codominant.

A/B/O alleles, being A and B codominant while O is recessive.

Rh factor: +/- positive (+) is dominant over negative (-) allele.

The child phenotype is: MN, A+.

This means at least on of the parents had to have one allele M, one N, one A and one positive (+).

The options given are phenotypes, not genotypes:

1) Mother (M): M, A  and Father (F): N, B- .  

This couple could be the parents. Mom´s genotype could be MM, AA,++ and dad´s one: NN,BO,-- .

2) M: MN,AB-  and F: M,O-.

In this case the kid could not be their child. Both parents are Rh negative. That means their genotype has to be --. And the kid has at least one positive allele.

3) M: MN, B+ and F: N,O+

In this case the child cannot be theirs either. A is dominant and neither parent has it in their phenotype.

4) M: MN, O+  and F: MN, A-

This couple could also be parents of the child, moms genotype could be MN, OO,++ while the father could be MN, AO, --  

They have at least on allele of the childs phenotype: MN, A, +

5) None of these.

False, we already identified two possible parents.

Correct answer: 1 and 4