Other Patterns of Inheritance Ch 11 3 Notes

Other Patterns of Inheritance Ch. 11. 3 Notes

Incomplete Dominance • Incomplete dominance results in an intermediate organism • Homozygous red snapdragon (RR) is crossed with a homozygous white (R`R`), you will get all offspring with pink flowers (RR`)

Codominance • Results in the expression of both alleles • Black chicken (BB) crossed with a white chicken (WW) will result in a: • Checkered Chicken(BW)!!!

Multiple Alleles • Traits controlled by more than two alleles –Only two alleles exist in each diploid cell –Sometimes up to 100 alleles for a single trait

Multiple Alleles – Three or more alleles determine these traits. Each person inherits only TWO of the alleles. • Ex. Blood types: A and B antigens found on RBC – Type A: IAIA IAi. O IA i. O – Type B: IBIB IBi. O I B I AI B IB i O – Type AB: IAIB – Type O: i. O i O I Ai O i O – Can a type A mother and type B father have a type O child?

Polygenic Inheritance • Skin color, height in humans • Controlled by two or more genes, each with two or more alleles. • Can be on the same chromosome or different chromosomes • Varies widely throughout the population.

Environmental Influences • External – Temperature, nutrition, light – western white butterfly, Siamese cats and arctic foxes, leaves

• Internal – Hormones – Mountain sheep horn size , humans (baldness), feather color in peacocks. (Male vs. Females)