Question

In cats the locus C for coat color is X-linked. CBCB females or CBY males are black. CYCY females or CYY males are yellow, and CBCY females are tortoise-shell (yellow and black splotches). A population of cats in London consisted of the following phenotypes:

Black Yellow Tortoise-shell

Males 311 42 0

Females 277. 7 54

Apply a procedure and calculate the gene frequencies of the alleles involved. Show your work.

Frequencies -

CB =

CY =

Answer 1

Black males = 311 , and genotype CBY

Black females=277, genotype CBCB

Yellow male = 42, genotype = CYY

Yellow female= 7 genotype = CYCY

Tortoise female = 54, CBCY.

Males have only 1 X , so they will alsways have only 1 allele. Females have 2 x and out of them 1 remains Inactivated in few body cells and in rest the other one giving tortoise coloring like a mosaic.

Total alleles = (males) + 2( no. Of females.)

= 311+42 + 2(277+7+54)

= 1029.

No. Of CB alleles = 311+ 2(277) + 54=919

No. Of Cy alleles = 42+54+2(7) =110

CB frequency = 919/1029 =0.893

CY frequency = 110/1029= 0.106