Genetics - Glossary

[Debbie]

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.