Question

Achondroplasia is an autosomal dominant form of dwarfism. People with achondroplasia are heterozygotes because carrying two copies of the dominant, mutant allele is fatal during embryogenesis. Two people with achondroplasia decide to start a family.a. Fill out a Punnett square for this couple.b. What is the probability that their first child born will be of average stature? c. What is the probability that this couple has two daughters with achondroplasia and one son of average stature in that order? d. What is the probability that this couple has two children with achondroplasia and one of average stature in any order?

Answer 1

Answer:

Part a: The Punnett square is attached

Part b: the probability that their first born will be of average stature is 1/4 or 0.25.

Part c:The combined probability is 0.5*0.25=0.125.

Part d:The combined probability is 0.5*0.25=0.125.

Explanation:

Part a

As parents are given as

Parents:  Aa x Aa

So the gametes are as

G1=AA

G2=Aa

G3=Aa

G4=aa

The Punnett square is attached with the solution.

Part b:

From the data of the gametes, the probability that their first born will be of average stature is 1/4 or 0.25.

Part c:

From the Punnett square, the probability that their two daughters have the achondroplasia is 1/2 or 0.5, while that of one son to be of average stature is 1/4 or 0.25. So the combined probability is 0.5*0.25=0.125.

Part d:

From the Punnett square, the probability that their two children have the achondroplasia is 1/2 or 0.5, while that of one child to be of average stature is 1/4 or 0.25. So the combined probability is 0.5*0.25=0.125.