Genetics Beyond Mendel Test

Incomplete Dominance

neither allele is fully dominant, resulting in a blended phenotype in heterozygotes (ex: red flower + white flower = pink flower)

codominance

both alleles are fully expressed in heterozygotes (ex: black horse + white horse = checkered horse)

multiple alleles

when more than two alleles exist for a particular gene (ex: blood types A, B, and O)

autosomal chromosomes

chromosomes that are not linked to sex chromosomes

polygenic traits

traits controlled by multiple genes (ex: height, skin color) → wide range of phenotypes

what’s the difference between multiple alleles and polygenic traits?

multiple alleles involve variations of a single gene and polygenic traits involve the combined effects of multiple genes

x-linked recessive

more common in males, affected males often inherit the trait from carrier mothers, traits can skip generations through female carriers

x-linked dominant

affected males will pass the trait onto all their daughters and none of their sons, affected females can pass the trait to both sons and daughters