28N Multiple Alleles

Multiple Alleles = more than 2 alleles are present for one gene Example: Human ABO blood types-there are 3 alleles Genotypes: Blood Types: IAIA or IAi AA or AO Type A IBIB or IBi BB or BO Type B IAIB AB Type AB ii OO Type O

AB (Universal Recipient) Multiple Alleles Blood Group Can give blood to Can receive blood from AB (Universal Recipient) AB AB, A, B, O A A, AB A, O B B, AB B, O O (Universal Donor) O

Percentage of the Population Multiple Alleles Blood Type Percentage of the Population O 43% A 40% B 12% AB 5%

Multiple Alleles Example 1: homozygous type A female X heterozygous type B male Genotype Ratio: 50% IAIB 50% IAi Phenotype Ratio: 50% Type AB 50% Type A IA IA IB IAIB IAIB i IAi IAi

Multiple Alleles Example 2: Type O female X Type AB male Genotype Ratio: 50% AO 50% BO Phenotype Ratio: 50% Type A 50% Type B O O A AO AO B BO BO

Charles Drew Found that blood cells can be frozen and stored Set up blood banks for transfusions

Polygenic Traits = traits controlled by two or more genes Examples: Skin, eye color, height influenced by the combination of different genes AABBCC = most amount of melanin (pigment) – darkest skin aabbcc = least amount of melanin –lightest skin AaBbCc = medium colored skin

Environmental Influence = an individual’s phenotype may depend on conditions in the environment Examples: Arctic fox – white in the winter and brown in the summer because the pigment producing genes do not work in the cold

Environmental Influence Siamese cats and Himalayan rabbits – have dark colored fur on their extremities The allele that controls pigment production can only function at the lower temperatures of those extremities