Question

In rabbits coat color is controlled by a single gene with 4 alleles: cC>cch>ch>c. cC = full color, cch= chinchilla, ch= Himalayan, c= colorless (albino rabbits). The Himalayan allele which results in a black nose, ears and paws is only functional below 30 degrees Celsius. At higher temperatures the protein doesn't function and the rabbits are albino. You cross two Himalayan rabbits. When you raise the progeny at 32 degrees Celsius, you get all albino bunnies. If you raise them at 25 degrees Celsius you get a 3:1 ratio of Himalayan to albino bunnies. What were the genotypes of the two parents?

Answer 1

The genotypes of the two parents are Cch and Cch. When the temperature is raised to 32 degrees Celsius, all the progeny rabbits would be albino. When the temperature is lowered to 25 degrees Celsius, a 3:1 ratio of Himalayan to albino bunnies is obtained.

Step-by-step explanation:

The genotypes of the two parents are Cch and Cch.

According to the information provided, the coat color in rabbits is controlled by a single gene with four alleles: C+, cch, ch, and c. The Himalayan phenotype, which has black fur on the extremities and white fur elsewhere, is caused by the ch allele. However, this allele only functions below 30 degrees Celsius. At higher temperatures, the rabbits are albino.

When two Himalayan rabbits with the ch allele are crossed, the genotypes of the parents would be Cch and Cch. Since the temperature was raised to 32 degrees Celsius, which is higher than the functional temperature range of the ch allele, all the progeny rabbits would be albino.

On the other hand, when the temperature is lowered to 25 degrees Celsius, within the functional temperature range of the ch allele, a 3:1 ratio of Himalayan to albino bunnies is obtained, indicating that 3 out of 4 progeny rabbits possess the functional ch allele.

Therefore, the genotypes of the two parents are Cch and Cch.