iluvyulots
Posted : 12/11/2006 12:15:28 PM
Cat genetics are very strange things, I'm only now beginning to understand them. With dogs its very simple. Black, white, brindle, chocolate, yellow, etc. But with cats, even these three toned type of colors are confusing. Theres Tortie, Tortie with white, Torbie (not sure what that is), Calico etc
The term Torbie is usually use when brown or blue/gray tabby patterns are seen. Some people also use the name Torbie term for Calicos with a tabby pattern. Coat coloration of a cat is very complex and it is controlled by several genes. One gene involves has two alleles: The
Orange allele,
O, which is the dominant form
(i.e., XO), and produces orange fur; and the "Back" allele, "o" which is the recessive form,
(i.e.., Xo), and produces black fur. For a cat to be tortoiseshell or calico, it must simultaneously express both of the alleles,
O and
o, which are two versions of the same gene, located at the same location on the X chromosome. Males normally cannot do that: they can only have one allele, as they only have one X chromosome. Virtually all tortoiseshell or calico cats are female for that reason. Occasionally a male is born (the rate is 1 in 3,000). These may have Klinefelter's syndrome carrying an extra X chromosome, and will almost always be sterile or they may be a chimera resulting from a fusion of two differently colored embryos. The spotted gene causes white patches to cover the colored fur. Although there is no genetic difference, the amount of white is artificially divided into mitted, bicolored, harlequin, and van, going from almost no white to almost completely white. In normal female tortoiseshell cats and in Klinefelter males, the position of the patches depends on which X-chromosome is active on each cell and which is inactive.
Ok that ends your genetic lessons for today lol. Hope that helps explain thins a bit better[

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