Incomplete Dominance, Codominance, Polygenic Traits, and Epistasis

Dominant Allele

An allele that expresses its phenotype even in the presence of a recessive allele.

Recessive Allele

An allele that only expresses its phenotype when two copies are present.

Incomplete Dominance

A non-Mendelian trait where the dominant allele is not completely expressed in the presence of a recessive allele, resulting in an intermediate phenotype.

Codominance

A non-Mendelian trait where both alleles are expressed fully in the phenotype.

Pleiotropy

A genetic phenomenon where a single gene affects multiple traits.

Polygenic Trait

A trait that is influenced by multiple genes.

Punnett Square

A diagram used to predict the genotype and phenotype combinations of a genetic cross.

Epistasis

A genetic interaction where one gene's expression depends on the presence of one or more other genes.

Phenotype Ratio

The ratio of different phenotypes that can be produced in the offspring from a genetic cross.

Genotype Ratio

The ratio of different genotypes that can be produced in the offspring from a genetic cross.