4 Exercises In each exercise below show your work and box, circle or underline y

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4 Exercises In each exercise below show your work and box, circle or underline your answer 1. Early-onset Parkinson disease 6 (PARK-6), an autosomal recessive trait, causes progressive nervous degeneration throughout a person's life. Arnold has been diagnosed with PARK-6, and his wife Nancy's father died of it. Genetic tests show that Naney will not get the disease. (a) What are Nancy and Arnold's genotypes? Nancy Arnold (b) Nancy is pregnant with Arnold's child. What's the probability that the child inherited PARK-6? 2. A man heterozygous for the PARK-6 marries a homozygous normal woman. Suppose they have three children. What is the probability that any of their children will develop PARK-6? Explain your response. 3. Mid-chin fissure is a dominant trait that obeys Mendel's first principle. Together, this trait and PARK-6 obey Mendel's second principle. Suppose a man who is heterozy gous for both traits marries a woman with a non-cleft chin who has PARK-6. What are the expected relative frequencies of phenotypes among their offspring, assuming they can have children? (NOTE: State the phenotypes associated with each frequency.) Nagy Rev: Spring 2018

Explanation / Answer

2.

PARK-6 is an autosomal recessive disorder.

So, the disease appears only in the homozygous mutant condition.

WT dominant allele = P

Mutant recessive allele = p

Parental cross: PP X Pp

Progeny: PP or Pp

There is no chance for any of the progeny to develop the disease.

3.

Mid chin fissure is a dominant trait.

M = Dominant mutant allele

m = Recessive WT allele

Parental cross: PpMm X ppmm

Gametes: (PM)(Pm)(pM)(pm) X (pm)

Progeny phenotypic ratio: 1:1:1:1

PpMm: PARK-6 = No; Mid-chin fissure = Yes

Ppmm: PARK-6 = No; Mid-chin fissure = No

ppMm: PARK-6 = Yes; Mid-chin fissure = Yes

ppmm: PARK-6 = Yes; Mid-chin fissure = No

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