Variations In Heredity

incomplete dominance codominancesex linkage

Incomplete Dominance

• the traits in Mendel’s pea plants exhibited complete dominance

• some alleles interact to produce a new phenotype; this is called incomplete dominance

Snapdragons

Codominance

• in codominance both alleles are expressed at the same time

Thomas Morgan Hunt

• American geneticist (1866-1945)

• studied the fruit fly• discovered sex

linkage

Sex linkage terms…

• autosomal inheritance• sex-linked• X-linked• Y-linked

Some sex-linked traits…

• red-green colourblindness• hemophilia A• male-pattern baldness

Pedigree Charts

Pedigree Charts

• Try the Practice questions on page 199…