Key Terms

Genotype

The genetic constitution of an organism

Phenotype

The expression of genes and its interaction with the environment

Homozygous

A pair of homologous chromosomes carrying the same alleles for a single gene

Heterozygous

A pair of homologous chromosomes carrying two different alleles for a single gene

Recessive Allele

An allele only expressed if no dominant allele is present

Dominant Allele

An allele that is always expressed in the phenotype

Codominant

Both alleles are equally dominant and expressed in the phenotype

Multiple Alleles

More than two alleles for a single gene

Sex-Linkage

A gene whose locus is on the X chromosome

Autosomal Linkage

Genes that are located on the same chromosome (not the sex chromosome)

Epistasis

When one gene modifies or masks the expression of a different gene at a different locus

Monohybrid

Genetic inheritance cross of a characteristic determined by one gene

Dihybrid

Genetic inheritance for a characteristic determined by two genes