Help fast!Description below:What are the genotypes of the parents? Complete the genetic cross and describe the ratio of blue to brown eyes among the children. What are the genotypes of the children?

Question

A women with blue eyes, a recessive trait, and a man with brown eyes, the dominant trait, have children with both blue eyes and brown eyes.

What are the genotypes of the parents?

Complete the genetic cross and describe the ratio of blue to brown eyes among the children.

What are the genotypes of the children?

Answer 1

Let's write a summary.

b = blue eyes. Need 2 copies to have blue eyes.

B = brown eyes. Only need 1 copy to have brown eyes.

The mother has blue eyes, so she must have two copies of the recessive gene. She is bb.

The father has brown eyes, so he has to have at least one copy of the dominant gene. He is B_

The children have a mix of blue and brown eyes, so they are bb and B_.

For a child to have blue eyes, the father would have to pass a copy of the recessive gene down. The father is Bb.

Now we can complete the cross to get the ratio. You can write a punnet square or do a probability calculation.

P(bb) = P(b_from_mother)*P(b_from_father)

P(bb) = 1*0.5

P(bb) = 0.5, so half of the children will have blue eyes

P(brown eyes) = P(BB) + P(Bb)

P(brown eyes) = P(B_from_mother)*P(B_from_father) + P(B_from_father)+P(b_from_mother)

P(brown eyes) = 0*0.5 + .5*1

P(brown eyes) = 0.5, so half the children will have brown eyes