Mary Allen
Many of you have certainly asked yourself: how can a long-haired kitten be born when the parents are short-haired? And why are most tortoiseshell cats female?
For a correct understanding, some terms of genetics must be briefly explained in advance. The cell is the basis of all living things. Cats, like humans, have countless numbers, and each cell has a specific job to do. Each cell contains the complete genetic information of a living being. This information is written and stored on the so-called chromosomes. Cats have 38 chromosomes per cell; 19 from her dad and 19 from her mom. 18 of the paternal chromosomes are very similar to the respective 18 of the maternal chromosomes – these are called autosomes. The other two, the gonosomes, are the sex-forming chromosomes. Females have two X chromosomes (XX), while males have one Y and one X chromosome (XY). The genes are located on the chromosomes. Each of them has a fixed place on the chromosome. The opposite genes on the maternal and paternal chromosomes are called alleles. If these opposing genes are exactly the same, then one speaks of homozygosity. If, on the other hand, the opposite genes differ, then the language is of heterozygous dispositions. All genes together are called the genotype and determine the individual. What you ultimately see, i.e. the coat color, the pattern, and the hair length, is called the phenotype.
A Long-Haired Puff Of Fur Despite Short-Haired Parents
Some genes are dominant and prevail in the phenotype against so-called recessive genes. Let’s take the hair length of cats as an example: a short coat is inherited dominantly, while a long coat is recessive. For the sake of simplicity, dominant genes are symbolized with a capital letter and recessive genes with a lower-case letter. In this case, the corresponding gene for the short coat is the “L” and that for the long coat is the “l”. There are 3 possibilities, for which genotype a cat can have for its coat length: “LL” (homogeneous; short coat), “ll” (homogeneous; long coat), or “Ll” (hybrid; short coat). If both the cat mom and cat dad have heterozygous coat length (“Ll”), a long-haired kitten (“ll”) can be born. Why? The little kitten gets one gene from her mom and one from her dad. If it gets the small “l” both times, then your genotype looks like this: “ll”. This is the genotype for the long coat phenotype.
The X Chromosome Makes The Cat Colorful
It’s a bit different when it comes to the inheritance of coat color. There are only two basic colors in cats, from which all other color shades arise through the influence of other genes: black and red. The genes responsible for these colors are not on an autosome like the gene for fur length but on a sex chromosome. More specifically, on the X chromosome. However, each X chromosome can only carry one color information. The Y chromosome, on the other hand, has no color. The result is that these two color shades are inherited in a gender-linked manner. As mentioned above, a female has two X chromosomes (XX). Depending on whether the cat has homozygous or mixed genes, it is one color or two colors (tortoiseshell). Male cats, which are known to have only one X chromosome, are almost always monochromatic. Their X chromosome contains either the information for the color “red” or for the color “black”. If a tortoiseshell cat is born, after all, this is due to the incorrect division of the germ cells (egg cell or sperm cell) of the parents. Instead of just one X chromosome, the mother passes on both X chromosomes to her cat. Or the dad passes on his two gonosomes to his offspring instead of just one of them. The tomcat, therefore, has the following genotypes: “XXY”. If each of the two X chromosomes also carries different color information, a tortoiseshell male is a result.