Question

Linh is a cat breeder and calico cats are in high demand among her clients. A gene on the X chromosome controls whether cats have orange or black fur. Calico cats are heterozygous for this gene and have patches of both orange and black fur.

A. Why do calico cats have patches of orange and black fur instead of a single color due to one dominant allele that completely masks the other?

B. Linh has requests for female calicos and orange male cats. Linh must choose between a black, orange, or calico female to breed with an orange or black male cat. Which female and which male should Linh choose in order to produce the highest yield of calico females and orange males:

Female:                                                                                  Male:

Black             Orange           Calico                                     Black              Orange

Explanation:

2. Garfield and Heathcliff are cartoon male cats that have patches of orange and black fur. Give one explanation for how this could be genetically possible.

Answer 1

A Answer

In calico cats, O dominant gene and the recessive o gene are x-linked. Orange is dominant over black.

X^B X^B orange fur

X^b X^b black fur

X^B X^b calico fur (orange and black patches)

The coloring is sex-linked and eumelanin is produced with   BB alleles and eumelanin produced phaeomelanin which completely replaces the red pigment and which results in black color.

Answer B

X^B Y is orange male cat

X^bY is black male cat

To get female calicos,

X^B X^b   female calicos

X^BY orange male cats

X^BX^B X X^bY ------> X^BX^b

orange female    orange male offspring calico female (more in number)   

X^BX^B X X^BY   -------> X^BY

orange female orange male offspring orange male (more in number)

Male XXY it is Klinefelter syndrome.

X^BX^bY produces calico colored males.

In Klinefelter syndrome, it has 2 X chromosomes. If it has got B and b alleles as it is given, it will develop calico color. 2 X go into the ovule and because of non-disjunction. If it combines with Y, XXY is developed. These 2 X are having B and b, a calico male is produced.