Coat color in cats is determined by genes at several different loci. At one locu

Question

Coat color in cats is determined by genes at several different loci. At one locus on the X chromosome, one allele (X^+) encodes black fur: another allele (X^0) encodes orange fur. Females can be black (X^+ X^+), orange (X^0 X^0), or a mixture of orange and black called tortoiseshell (X^+ X^0). Males are either black (X^+ Y) or orange (X^0 Y). Bill has a female tortoiseshell cat named Patches. One night, Patches escapes from Bill's house, spends the night out, and mates with a stray male. Patches later gives birth to the following kittens: one orange male, one black male, two tortoiseshell females, and one orange female. What was the genotype of the stray cat with which Patches mated? X^+ Y X^+ X^0 X^0 Y X^0 X^+ YY

Explanation / Answer

The correct answer is option c) X0Y. In this case, Bill has a female cat. Thus, the stray cat has to be a male. So, all the other options with no Y chromosome are eliminated.

The genotypes of the offsprings will be:

Orange male: X0Y

Black male: X+Y

Tortoiseshell females: X+X0

The cross that takes place is as follows:

(Patches) -> X+X0      X0Y <- (Stray Cat)

/

   X+X0 , X0 X0 , X0Y, X+Y

(Kittens: Tortoiseshell females, Orange Female, Orange male and Black male respectively).

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