Understanding Genetic Terms
Term
Definition
Agouti Is the descriptive term applied to the background (or non-tabby) hairs that are banded with several bands of color that give an overall appearance of a lighter color.  (Gray or tan in the wild type.)
Albino An organism born without pigment in the eyes, skin, or hair.  These individuals often appear to have pink or whitish blue eyes (not because of color but because of the lack of pigment allowing the pink from the blood vessels of the retina and just under the skin to show through.
Allele Used interchangeably with "gene".
Blended Character See Incomplete Dominance.
Characteristic Term for the trait i.e.: eye color, etc.
Checkerboard Diagram A chart used to graph the percentages of expected offspring of any given cross.
Chromosome The "thread" of genetic material carrying the genes.  Always found in pairs and always the same number in a given species.  One from each pair is given to the eggs and sperm so that each offspring receives one strand for each parent to make up it's own pairs so that the number always stays the same.
Dilute A gene in the feline that spreads out the Eumelanin or Phaeomelanin pigments causing the color to appear lighter so that black now appears blue, red appears cream, etc.
Diploid Full number of Chromosomes.  This is the number of chromosomes found in every cell in the body except for the eggs or sperm cells.
DNA Deoxyribonucleic Acid  (The genetic blueprint of all life.  commonly call a gene.)
Dominance A trait capable of carrying another trait.  (Ex: spotted tabby carries marble.) [Note, this term only applies to traits at the same locus.)
Dominant White A trait that masks all colors and patterns so the cat appears white no matter what other genetic colors are there.  Also sometimes called "Supper Dominant"
Embryo The developing offspring during the earliest part of its development.  (Generally the embryo is called a fetus once the bones have calcified.)
Eumelanin (Black based melanin)  These are pigment granules thought to be round to oval in shape and absorb nearly all light.
Felial Refers to a generation.  (F1 is the first felial generation of a cross of unrelated individuals.
Gene The protein molecule that carries the genetic code for each trait and biological function and process down to the cell level.
Haploid Half of the number of chromosomes (singles no pairs).  This is the number found in the germs cells (sex cells) or egg or sperm cells.
Heterozygous A trait that has one dominant gene and is carrying one recessive gene.
Heredity The passing of traits from one generation to another through DNA.
Homozygous Both genes for a particular trait are the same i.e.: AA or aa
Incomplete Dominance A situation where neither gene dominates the other and both exercise an influence on the individual.  Also called co-dominance, & blended character.
Inhibitor gene This gene is dominant and is an example of a dominant mutation.  The inhibitor gene stops the action of the agouti banding on the hairs of the background so that they are all white (no pigment is allowed into the hair shaft at the point when it would normally flow into the hair of the developing embryo).  This gives these hairs a "silver" appearance.  To have a "normal" color cat 2 non-inhibitor genes (ii) are required.
Locus (plural loci) This is the location of a particular gene on a specific chromosome.
Meiosis "Normal' cell division where the cells create and exact duplicate of themselves.
Melanin Black pigmentation of the skin, hair, &/or eyes.
Melanistic A recessive condition which is the lack of expression of the agouti gene causing the background fur to be solid black.  (Actually a black pattern on a black background.) In cats with a different color gene (i.e.: red) the effect is solid red, etc.  It is not the inheritance of color but of solid due to the non-agouti genes.
Mitosis Cell division where the chromosome number is only half of the number found in the "normal" cells of the individual creating egg or sperm cells.
Mutation A change in the action of a gene.
Phaeomelanin This is the red pigmentation of the skin, hair, &/or eyes.
Pigmentation The amount of melanin (Color containing cells) in the skin, hair, & eyes. 
Recessive A trait that is carried by an individual but is not expressed and is completely unseen.
Synthesizing The formation of the cells creating the color in the hair shaft.
Tarnishing This term is used by silver breeders to describe the areas where the inhibitor action failed and allowed some synthesis of the brown color to come through.  Usually on the nose, face, and down along the back.
Ticking This term is sometimes confused with agouti but is usually applied to the areas of pattern hairs that are ideally solid but show some "ticking" within the patterned area of the coat. Some hairs having a lighter color at the tip of some of the yellow agouti ticking in the areas that should be solid.
Zygote A fertilized cell that will become the embryo.
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