In cats the allele B produces black, whereas b produces yellow. Neither gene is dominant, and in the heterozygous state the phenotype is a combination of yellow and black spots called tortoise-shell. The alleles B and b are “X-Linked”. If a tortoise-shell cat has three tortoise-shell kittens and two black kittens, give the genotype and phenotype of the tomcat that produced them, and give the sex of the kittens.

Question

In cats the allele B produces black, whereas b produces yellow. Neither gene is dominant, and in the heterozygous state the phenotype is a combination of yellow and black spots called tortoise-shell. The alleles B and b are “X-Linked”. If a tortoise-shell cat has three tortoise-shell kittens and two black kittens, give the genotype and phenotype of the tomcat that produced them, and give the sex of the kittens.

Answer 1

To determine the genotype and phenotype of the tomcat that produced the kittens, we need to analyze the information provided.

First, it is mentioned that the gene responsible for coat color in cats is "X-Linked." This means that the gene is located on the X chromosome.

The alleles for the coat color are B (black) and b (yellow). It is also stated that neither of these alleles is dominant, and that the phenotype for heterozygous cats (Bb) is tortoise-shell (a combination of both black and yellow spots).

Given that the mother is a tortoise-shell cat, she must have two X chromosomes, one carrying the B allele and the other carrying the b allele. Therefore, her genotype would be XBXb (Bb).

Now, let's analyze the offspring. If a tortoise-shell cat (XBXb) has three tortoise-shell kittens (XBXb) and two black kittens, we can infer the following:

1. Phenotype of the tomcat: Since the mother is tortoise-shell and has two X chromosomes (XBXb), the tomcat must contribute a Y chromosome for all the kittens since only males can have a Y chromosome.

2. Genotype of the tomcat: To produce tortoise-shell kittens, the tomcat must have the B allele (XBY) since the B allele produces black. Since none of the offspring are yellow, we can conclude that the tomcat does not have the b allele. Therefore, the genotype of the tomcat would be XBY.

3. Sex of the kittens: Since the mother (XBXb) contributes one X chromosome to all the kittens, the sex of the kittens will depend on whether the father contributes an X or Y chromosome. In this case, since the tomcat has a Y chromosome (XBY), it means that all the kittens will be female (XX) since the gender of a cat is determined by the presence of an X chromosome (XY for males, XX for females).

In summary:
- The genotype of the tomcat that produced the kittens is XBY.
- The phenotype of the tomcat would be black since it carries the B allele.
- All the kittens will be female (XX).