Alleles: Alternative forms of a genetic locus; a single allele for each locus is inherited separately from each parent and can be dominant or recessive.
Chromosomes: The self- replicating genetic structures of cells containing the cellular DNA
DNA (deoxyribonucleic acid): DNA is a double- stranded molecule that encodes genetic information.
Locus: The position on a chromosome of a gene or other chromosome marker. Each locus holds a gene for each trait from each parent.
Germ cell: The sex cells (egg and sperm). In a rat, each germ cell has 21 genes. When combined at conception the result will be 42 genes.
Somatic cell: These are all cells other than sex cells. Also called “body” cells.
Homologous: Having two of the same alleles on the same gene (one inherited from each parent such as 2 recessives or 2 dominants. (homo means the same)
Heterozygous: having two different alleles of the same gene (one inherited from each parent) such as one recessive and one dominant. (hetero means opposite)
Dominant: Requires inheritance of only one copy of a gene to exhibit a trait
Recessive: Requires inheritance of two copies of a gene to exhibit a trait
Carried: Genes that an individual possesses without exhibiting a trait.
Diploid: A full set of genetic material, consisting of paired chromosomes one chromosome from each parental set. All body cells are diploid.
Haploid: A single set of chromosomes (half the full set of genetic material) as in the egg and sperm (germ)cells of animal
Modifier genes: Genes that affect the level of expression of another gene. Having no place on the Loci they attach themselves to other genes.
Phenotype: The outward appearance of an individual
Genotype: The genetic makeup of an individual
Sex-linked: Traits or diseases associated with the X or Y chromosome; generally seen in males.
Penetrance: The percentage of individuals in a population that actually exhibit the (mutant) phenotype even though they carry the mutation
Expression: This refers to the consistency of the mutation. Basically even though the mutation penetrates it may have variable degrees of expression.
Lethal Gene: A gene that results in death. Lethal genes can be either dominant or recessive.
The Rat Guide and its affiliates accept no responsibility for misuse or misunderstanding of its information. This guide in whole or part, exists solely for the purpose of recognizing and understanding the care and illnesses in the pet rat. Please seek advice and treatment from a qualified Veterinarian if your rat is ill.
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