Hello all!
This article is likely going to be brief, considering the black factor at the very basic level for feline genetics is rather simple. To start with we need to discuss the two types of pigments. Melanin is what creates these pigments and every color is made from these two pigments. They are default colors; however, they can be modified by other genes to make a new phenotype. Eumelanin is black pigmentation, otherwise known as black factor. This is the type we will be discussing in this article. Phaeomelanin is red pigmentation, otherwise known as red factor. This will be discussed in a different article. Eumelanin and Phaeomelanin can become many different colors, or phenotypes, based on how much is distributed and where it is distributed. Eumelanin can even affect the eyes and nose!
In the previous article, we discussed several terms; two of those terms were dominant and recessive. Black > Chocolate > Cinnamon; this means that black is dominant to both chocolate and cinnamon, but chocolate is dominant to cinnamon and recessive to black. If you remember us discussing alleles before, you know that the allele is b for the locii black factor. The following table tells us what these alleles mean!
Black Factor
| Description | Genotype | Phenotype |
|---|---|---|
| Black | BB | Black |
| Black carrying chocolate | Bb | Black |
| Black carrying cinnamon | Bbl | Black |
| Chocolate | bb | Chocolate |
| Chocolate carrying cinnamon | bbl | Chocolate |
| Cinnamon | blbl | Cinnamon |
So we have our first locii determined! So what happens if we cross two black cats that carry chocolate?
| B | b | |
| B | BB | Bb |
| b | Bb | bb |
This is called a Punnet Square and is a very useful tool to determining phenotypes from a genotype. You take one parent's alleles (Bb) on the left hand side and the other parent's alleles (also Bb) on the top and bring those letters together in the middle. This tells us there is a 25% chance of BB, 50% chance of Bb, and 25% chance of bb. That means 75% of the cats will have a phenotype of black and 25% of the cats will have a phenotype of chocolate.
That's all for black factor at the very simplest! I'd like to just put a couple pictures to display what these colors look like.
Black
(Image by http://klarititemplateshop.com/ found at Flickr.com)
Chocolate
(Image by Pete Riches, found at Flickr.com)
Cinnamon
(Image by Amenhi, found at Flickr.com)