Allele

One of two identical or alternative forms of a gene that occupy the same position on  chromosome.

Autosome

A non sex determining  chromosome. The cat carries 38 chromosomes: 36 autosomes and 2 sex chromosomes

Cell

The basic unit of all living organisms.

Chromosome

Chromosomes are thread like structures that are arranged in pairs within each body cell. Each chromosome carries the cat's genetic information in the form of genes. 

Dominant

A dominant gene is one that dominates another gene (recessive) by masking its character.  For example a cat may have a black coat (dominant gene) but also be carrying the gene for blue coat (recessive). The dominant black coat is what we see because the expression of the recessive blue coat is masked.  The black coat dominant gene is symbolized by the capital letter B. As there are a pair of genes for each trait, the symbolization for black coat would be BB homozygous or Bb heterozygous.

DNA

DNA is a shortened form for Deoxyribose Nucleic Acid. the genetic material in the nucleus of every cell .

Epistasism

A term used to describe the action or masking of a characteristic that is non-allelic (not part of a pair of alleles), for example, the white coat gene, expressed symbolically as W, dominates over all other colours and patterns including dominant genes for a particular characteristic.

Filial (F)

Latin for "son". Kittens produced in the first filial generation are expressed as F1 and if the offspring of the F1 are mated, the subsequent filial generation is referred to as F2.

Gamete

Unfertilised female ova (egg) or male sperm cells

Gene

In its simplest form, a gene is the basic unit of genetic material that determines different inherited characteristics, such as red hair or blue eyes. They carry the coded information that determines what, that we inherit from our parents Genes are carried on chromosomes  and occur in pairs called alleles.

Genotype

The complete genetic makeup of an individual.

Heterozygous

Mixed genotype where the cat has inherited a dominant gene from one parent and a recessive gene from the other parent. The expression or visible aspects of the cat are those of the dominant gene (black coat) but the second, recessive blue coat gene is masked.

Homozygous

Pure genetic makeup where the two genes are identical, for example this can be expressed as BB for black coat and bb for blue coat.

Inhibitor

Genes that inhibit the expression of another gene. This can be full inhibition or only partial expression

Masking

When the expression of one gene masks another as in dominance and recessive expression. Masking can also occur when a patterned coat, such as Tabby, is masked by a solid colour.

Modifiers

Genes which have modifying effects on colour genes

Phenotype

The physical and behavioural expression of an animal's genetic characteristics.

Recessive

A cat needs to carry two recessive genes for a particular character such as blue coat  (bb) for it to be expressed as a visible characteristic.

Masking

When the expression of one gene masks another as in dominance and recessive expression. Masking or epistasis can also occur when a patterned coat, such as Tabby, is masked by a solid colour.

Mutation

A change (usually spontaneous) in the genetic material (DNA) of a cell, or the change this causes in the characteristics of the individual which is not caused by normal genetic processes.

Nucleus

The part of the cell that contains the genetic material.

Sex Chromosome

A chromosome that is involved in the determination of the sex of the individual Women had two X chromosomes and men have one X and one Y chromosome

Zygote

The fertilized ovum/egg before the cells begin to divide to become a foetus