Albino – having absent or deficient melanin. Widely used term for "amelanistic". See tyrosinase-negative and tyrosinase-positive.

Allele - either of the two paired genes which affect an inheritable trait.

Amelanistic - having no melanin.

Anerythristic - having no red color.

Axanthic - having no yellow color.

Codominant - a gene that causes the homozygous form to look different than the wild-type and the heterozygous form to have traits of both.

Dihybrid Cross - shows the possible genotype of offspring as the result of the pairing of two different genes.

DNA (Deoxyribonucleic Acid) - molecules bearing genetic information of all living cells. Gene. Also referred to as “unit of inheritance.”

Dominant - a gene that causes an animal to look different than the wild-type and where the homozygous form and the heterozygous form look the same as each other.

Double Heterozygous - being heterozygous for two different traits.

Gene - unit of heredity that determines the characteristics of the offspring.

Genetics - the study of heredity.

Genotype – an organism’s genetic composition. Heredity - the transmission of genetic characters from parents to offspring.

Het – an abbreviation for heterozygous.

Heterozygous – possessing two different genes for a given trait. An animal with one mutated, recessive gene still appears normal; its mutated gene can be inherited by future offspring. A codominant animal is heterozygous for the dominant form of its mutated gene, yet is different in appearance than both the wild-type and homozygous forms.

Homozygous – A state in which both genes for a specific trait are the same. When a recessive gene is it its homozygous form, it makes the animal look different from the wild-type. When a dominant gene is in its homozygous state, it causes the animal to look different from both the wild-type and the heterozygous (codominant) forms.

Hypomelanistic - an animal having less black and/or brown color than a wild-type.

Leucistic - a pure white animal with dark eyes.

Locus - a gene's position on a chromosome (plural: loci).

Melanin - black or brown skin pigments.

Melanistic - abnormally dark, especially due to an increase of melanin.

Mutation - an abnormal gene that under certain circumstances can cause an animal to be born with an appearance other than wild-type.

Normal - an animal with no mutated genes - "wild type" in appearance. (See wild type).

Phenotype – an animal’s external apperance, as caused by its genotype.

Possible Het. - an animal from a known breeding that has either a 50% or 66% possibility of being "heterozygous" for a mutant gene.

A 66% possible het comes from breeding 2 heterozygous animals together: 50% of the offspring are heterozygous, 25% will be homozygous, and 25% will be wild-type. Of the normal appearing animals, 66% (or roughly 2 out of 3) will actually be heterozygous for the mutated gene.
A 50% possible het comes from breeding a heterozygous animal to a wild-type animal. All of the resulting offspring will be wild-type in appearance, but 50% of them will actually be heterozygous for the mutated gene and must be bred out to determine which animals are really hets.

Recessive - a gene that affects an animal's appearance if it's present in the homozygous state. A heterozygous animal carrying a mutated, recessive gene looks normal.

Super - commonly used herpetocultural term for the dominant form of a co-dominant mutation. i.e. Super Motley.

Tyrosinase - an enzyme required for synthesizing melanin.

Tyrosinase-negative - an albino whose cells lack tyrosinase, producing a white and yellow/orange animal with pink eyes. A separate albino mutation from tyrosinase-positive. Also called T-.

Tyrosinase-positive - an albino not able to synthesize melanin, but capable of synthesizing tyrosinase. Also referred to as T+.

Wild-type - the way the animal usually looks in nature (i.e. the normal color and pattern).

Xanthic - having more yellow color than wild-type.