In cats there is a coat color gene located on the X chromoso

In cats, there is a coat color gene located on the X chromosome. This gene has two alleles. The dominant allele codes for a protein that results in orange hair and it is incompletely dominant to the recessive allele that codes for black hair. The heterozygote has tortoise shell color hair (a mix of orange and black). State the phenotypes that are possible and the probability of having an offspring with each phenotype for a cross between a black female and an orange male.

The length of cat hair is controlled by one gene with two alleles. The L allele codes for short hair and the l allele codes for long hair. Using the information on coat color from problem “a”, state the phenotypes that are possible and the probability of having an offspring with each phenotype for a cross between a long-haired black female and a heterozygous short-haired orange male.

Cats have a gene known as the white masking gene, which has 2 alleles. The W allele produces a protein that prevents the production of pigment producing cells. The w allele produces a protein that results in normal production of pigment producing cells. The WW and Ww genotypes produce white cats no matter what other color genes they carry. Only ww cats will express their normal pigmentation.   Using the information from problem “b”, state the phenotypes that are possible and the probability of having an offspring with each phenotype for a cross between a long-haired black female cat that is homozygous recessive for the white masking gene and a male cat that is heterozygous for the short-haired gene, heterozygous for the white masking gene and carries the orange allele on its X chromosome.

Solution

1. Let orange color= O, black color= B

Phenotypes possible= (OO genotype) Orange, (OB genotype) Tortoise, (BB genotype) Black

If BB X OY (since a male has only one X chromosome)

All girl offspring will have a tortoise shaded coat color, all males will be black.

Probablity for tortoise shaded offspring= 0.5

for black shade offspring= 0.5

Therfore, probability for each phenotype= 0.5

2. llBB (long haired black female) X LlOY (short haired orange male)

Therefore, probablity for each phenotype= 0.25

3. llwwBB (long haired black white recessive female) X LlWwOY (short haired white male)

LlwwOB (short haired tortoise female)

Therefore, probabilty for each phenotype= 0.125