BEYOND DOMINANT AND RECESSIVE ALLELES INCOMPLETE DOMINANCE NEITHER

BEYOND DOMINANT AND RECESSIVE ALLELES

INCOMPLETE DOMINANCE -NEITHER ALLELE IS COMPLETELY DOMINANT OVER THE OTHER -THE HETEROZYGOUS PHENOTYPE IS SOMEWHERE IN BETWEEN THE TWO HOMOZYGOUS PHENOTYPES

EXAMPLES OF INCOMPLETE DOMINANCE Snapdragons: A cross between redflowered and white-flowered results in pinkflowered

Red is incompletely dominant to white. Write the genotypes for each flower below. Red flower _____ Pink flower _____ White flower _____

Horse coat color: A cross between a white horse and chestnut brown horse results in a golden palomino

Even in humans. . . -Pitch of human male voices: -Lowest pitch (LL) and highest pitch (ll), but the intermediate range baritones are (Ll) Guess the genotypes: ______

CODOMINANCE -BOTH THE DOMINANT AND RECESSIVE ALLELES ARE EXPRESSED IN THE HETEROZYGOUS INDIVIDUAL -SO NEITHER ALLELE IS REALLY “DOMINANT”

EXAMPLES OF CODOMINANCE Chickens: Heterozygous chickens have a color described as “erminette” which is speckled with black and white feathers

Cattle: A homozygous red bull and a homozygous white cow will produce a heterozygous roan offspring

Write the genotype for each listed animal. Red cow ______ Roan cow ______ White cow ______

EVEN IN HUMANS. . . Humans have 4 possible blood types: A, B, AB, and O. Those individuals who have AB blood (and there aren’t many because it is rare) have characteristics of both A and B blood types.