Posted September 1, 2007 Here are some useful terminology and meanings. Homozygous - two identical alleles on the corresponding gene loci. Heterozygous - two different alleles on the corresponding gene loci. Phenotype - an animals appearance/charactisterics Genotype - an animals genetic makeup Mutation - in this case, any colour that is not Standard Chromosome - Structures in a cell's nucleus that house the genes (chinchillas have 64!!) Allele - one of two alternate forms of a gene that can have the same locus on chromosomes. They may be responsible for alternative traits - i.e. some alleles are dominant over others. Locus - A locus describes the position of a gene on a chromosome. A locus can be occupied by any of the alleles of the gene. (Leading us - once again to the term homozygous = (have the same allele at a locus) or heterozygous = (have different alleles at a locus). TOV - An American term "Touch of Velvet" meaning a chinchilla with the "Velvet" gene Standard - Standard Grey - the natural colour of chinchillas Lethal Gene Factor - certain colours (white and velvet) are not viable if homozygous for that colour (i.e. they can only exist in the heterozygous state). These colours are said to have a "lethal factor". Carrier - A chinchilla of any particular phenotype may "carry" a single gene for another colour. i.e. may be a heterozygous carrier for a recessive colour. Recessive colours are only expressed in the homozygous state (when a chinchilla inherits both genes). A chinchilla can carry more than one recessive colour - if bred to do so. Recessive Inheritance - Two chinchillas carrying one recessive gene, although carriers, are not violet coloured - as they only have one gene apiece (recessive colours only express themselves in the homozygous (2 gene) state). Dominant Inheritance - One parent has a single, dominant gene (i.e. black velvet) - which appears phenotypically. When the parent mates with a "normal" or standard (non-carrying) mate, the offspring will either be Black velvet or standard, but they are never carriers as the dominant gene cannot be carried. Share this post Link to post Share on other sites More sharing options...