Genetics of Calico cats

Tortoiseshell—no white patches

Calico with white patches—white is controlled on a separate gene.

Calico cats: X linked gene In cats, base coat color is on the X chromosomes. Male cats have only one X chromosome, so can only express one base color. Females have two X chromosomes, so can express two base colors. For example, say the sire of a kitty contributed the black gene and the dam contributed the orange gene.

The inactivated X chromosome is called a Barr Body. Dosage compensation keeps females (XX) from expressing twice as much of X-chromosome genes as males (XY), who have only one X chromosome. Both sexes are rendered roughly equal by the inactivation of one X chromosome in females. The inactivated X chromosome is called a Barr Body. Barr Body

Calico cats: X-inactivation in action It is thought that early in embryonic development, X-inactivation occurs randomly (maternal or paternal chromosome is not targeted) in somatic (body) cells of females. Once inactivation has occurred, the same X chromosome will be inactivated in future cells after mitotic cell division.

When some of the black alleles are inactivated, and some of the yellow/orange alleles are inactivated in other cells, the results are a calico cat

Does cat coat color determine personality? A study published in 2012 researched how people perceive cat personalities based on coat colors. Interested to know more? (can be used as a Current Events extra credit article…) news.berkeley.edu/2012/10/23/cat-color/

Videos Why are calico cats female? Polydactyl calico https://www.youtube.com/watch?v=6LozN-TZro8 Polydactyl calico https://www.youtube.com/watch?v=7lNmF5goKNI Calico cat stalking hungry squirrel https://www.youtube.com/watch?v=MaW8rhSgEUs