Question

problem #4
if a paternity test revealed that a man with heterozygous b blood was the father of a child with ab blood, than what would be the two possible genotypes of the mother? if you need, use the space below to make punnett squares if you need it.
sex - linked inheritance is different from all the other types of inheritance we have learned so far because your gender plays a significant role in the chances of inheriting a particular trait or a disease. these genes are found on x chromosomes. females have two x chromosomes and males only have one (the other sex chromosome is the y). because females have two x chromosomes, they are usually at an advantage in terms of inheriting “bad” genes located on the x chromosome. if you inherit one of these genes on one x chromosome, you may have another x chromosome with the normal gene that will mask the effects of the “bad” gene. males, on the other hand, have only one x chromosome. if they inherit a “bad” gene from their mom (the x chromosome), they are stuck with that particular trait or disease. look below for examples.
blood clotting and normal color vision are two genes carried on the x chromosome of all humans. hemophilia (the inability to make platelets so your blood clots when you get cut) and colorblindness occur when a person inherits a mutated and recessive version of this gene.
female with normal blood clotting ability (homozygous dominant) x^nx^n
female with normal blood clotting ability (heterozygous) x^nx^n
female with hemophilia (homozygous recessive) x^nx^n

Explanation:

Step1: Determine father's genotype

The man has heterozygous B - blood, so his genotype is $I^B i$.

Step2: Analyze child's genotype

The child has AB - blood, so the child's genotype is $I^A I^B$.

Step3: Deduce mother's possible genotypes

Since the child has an $I^A$ allele which must come from the mother, and considering the blood - type inheritance system, the mother could have genotype $I^A I^A$ (homozygous A) or $I^A i$ (heterozygous A).

Answer:

$I^A I^A$, $I^A i$