biology genetics

Genotype

The genetic constitution of an organism (the alleles it has for a gene)

Phenotype

The expression of the 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 will always be expressed in the phenotype

Codominant

Both alleles are expressed in the heterozygote resulting in a different phenotype

Multiple Alleles

More than two alleles for a single gene

Sex-linkage

A gene whose locus is on the X (or Y) chromosome

Autosomal Linkage

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

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 cross for a characteristic determined by two genes