Genetic problems

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Slide 35

Question #5D

What are the chances that they would have a child whom lacks both freckles and dimples?

FD Fd fD fd

Fd FFDd FFdd FfDd Ffdd

fd FfDd Ffdd ffDd ffdd

Answer: 1/8

Slide 36

Question #6

Sixteen percent of the human population is known to be able to wiggle their ears.

This trait is determined to be a recessive gene.

These is a population genetics question.

Use the following equation: 1 = p2 + 2pq + q2

Slide 37

Question #6A

What of the population is homozygous dominant for this trait?

q2 = 16% or .16: q2 = .16

q = .4

then use : 1 = p + q

1 = p + .4

1- .4 = p

p = .6

Now use p2 for answer: .62 = .36 or 36%

Slide 38

Question #6B

What of the population is heterozygous for this trait?

We know that q = .4 and p = .6

Now use 2pq for answer: 2(.6)(.4) = .48 or 48%

Slide 39

Question #7

In dogs, the inheritance of hair color involves a gene B for black hair and gene b for brown hair b.

A dominant C is also involved. It must be present for the color to be synthesized.

If this gene is not present, a blond condition results.

BB, Bb - black hair CC, Cc - color

bb - brown hair cc - blond

Slide 40

Question #7A

A brown haired male, whose father was a blond, is mated with a black haired female, whose mother was brown haired and her father was blond.

Male: bbCc (gametes: bC bc)

Female: BbCc (gametes: BC Bc bC bc)

What is the expected ratios of their offspring?

Slide 41

Question #7A

BC Bc bC bc

bC BbCC BbCc bbCC bbCc

bc BbCc Bbcc bbCc bbcc

Offspring ratios:

Black: 3/8

Brown: 3/8

Blond: 2/8 or 1/4

Slide 42

Question #8

Henry Anonymous, a film star, was involved in a paternity case. The woman bringing suit had two children, on whose blood type was A and the other whose blood type was B.

Her blood type was O, the same as Henry’s!

The judge in the case awarded damages to the woman damages to the woman, saying that Henry had to be the father of at least one of the children.

Slide 43

Question #8A

Obviously, the judge should be sentenced to Biology. For Henry to have been the father of both children, his blood type would have had to be what?