Question

18-20.) Blood type is a trait that exhibits codominant inheritance. Rena, who has blood type B, and Jake, who has blood type AB, are expecti When the baby is born, it is determined that it has blood type A. From this information, you can determine what Rena's genotype is. Explain what her genotype is Draw out the Punnett square and indicate what blood types you can expect to see in created from their mating. What is the ratio you expect? (3 points) ng a baby together. ned this and how you determi offspring

Answer 1

18-20) There are three alleles in ABO blood grouping that determine the phenotypes of the blood. These are I^A, I^B & i. I^A & I^B are co-dominant to each other & are dominant to i. People with I^AI^A or I^Ai genotype will give type A blood, I^BI^B or I^Bi will give type B blood, I^AI^B will give type AB blood & ii will give type O blood. As Rena & Jake's blood groups are B & AB respectively & their child have type A blood, so Rena must have genotype I^Bi. If Rena have I^BI^B genotype then type A blood of the child was not possible. Both scenarios are shown in below Punnett squares.

If Rena has I^BI^B genotype:

Gametes	IA	IB
IB	IAIB (Type AB blood)	IBIB (Type B blood)
IB	IAIB (Type AB blood)	IBIB (Type B blood)

If Rena has I^Bi genotype:

Gametes	IA	IB
IB	IAIB (Type AB blood)	IBIB (Type B blood)
i	IAi (Type A blood)	IBi (Type B blood)

So, from the above Punnett square we find that we can expect type A, B or AB blood group in the progeny of their mating. The ratio of A, B & AB will be 1:2:1.