Genetic Terms

• Allele - a variation of a gene
• Codominant - when two dominant alleles can express together
• Diploid - an animal that has two copies of each chromosome; one from the mother and one from the father
• Dominant - an allele is considered dominant if it can be expressed in an animal that only has one copy of the allele
• Epistatic - a gene that changes the expression of another (hypostatic) gene at a different locus
• Express - when a trait is visible on the animal
• Gene - a sequence of one or more nucleotides in a DNA molecule that makes up a basic unity of heredity
• Genotype - the type, or allele, for a gene
• Heterozygous - when the alleles in a pair of genes are different
• Homozygous - when the alleles in a pair of genes are the same
• Hypostatic - a gene that expresses a different phenotype depending on another (epistatic) gene
• Incomplete Dominance - or partial dominance, when a dominant allele doesn’t completely mask a recessive allele and creates a blended phenotype
• Linkage - when two genes are near each other and tend to inherit together
• Locus - the location of a gene
• Loci - plural of locus
• Mendelian Inheritance - usually refers to single-gene, single-trait inheritance
• Phenotype - a visible trait
• Pleiotropic - when a single gene affects multiple phenotypes
• Polygenic - when multiple genes interact to produce a phenotype
• Recessive - an allele is considered recessive if it can only be expressed when both alleles in a gene are the same
• Recessive - an allele is recessive if the gene must be homozygous in order to express the trait
• Wild Type - a wild type allele is considered the non-mutated, or wild, variation of a gene

---