Bio quiz 21

Heterozygous

carries one dominant and once recessive allele for that gene; e.g. Tt

Homozygous Recessive

Carries two recessive alleles for that gene; e.g. tt

Monohybrid Cross

Involves examining only one trait

Dihybrid Cross

Involves examining two traits

Pedigree

a.k.a family tree of genes/traits; a chart that shows how a trait and the genes that control it are inherited w/in a family; black is used to represent the recessive allele

Carrier

An individual who carries a recessive trait that is NOT expressed in that individual

Incomplete Dominance

When the two alleles for a trait do not exhibit a true dominant/recessive relationship; the heterozygote shows a phenotype that is "in between" the phenotype of the two homozygous parents; both alleles are partially expressed in the heterozygote; e.g. Mirabilis ("4:00 flowers"), palominos

Codominance

Both alleles in the heterozygote express themselves fully; eg.g "Erminette" chickens human blood type, roan cows

Multiple Alleles

A gene which has three or more alleles that exist in a population; e.g. coat color in rabbits, human blood type

Polygenic Traits

A trait that is controlled by 2 or more genes; shows a wide range of phenotype; e.g. human skin and eye color