Incomplete Dominance & Codominance

Incomplete Dominance Red (RR) White (rr) Pink (Rr) Defined: Neither allele is completely dominant Heterozygous = blended appearance More than 2 different phenotypes can occur Ex: Many flower colors

List the genotypes possible. 100% Rr List the phenotypes possible. Example: Cross an incomplete homozygous dominant red carnation (RR) with an incomplete homozygous white carnation (rr). List the genotypes possible. 100% Rr List the phenotypes possible. 100% Pink r r R R R r r pink pink R R r r pink pink

R r R r r r r pink white R r r r pink white Example: Cross one heterozygous pink (Rr) carnation with a white carnation (rr). List the genotypes possible. 50% Rr 50% rr List the phenotypes possible. 50%Pink 50%White R r R r r r r pink white R r r r pink white

Codominance red white roan Defined: When both alleles are dominant and equally expressed The colors do NOT blend together, but are equally seen Ex: Cattle Coat Red cow x White cow = Roan Cow Ex: Human Blood types Type A x Type B = Type AB red white roan

Incomplete vs. Codominance Codominance: Both equally expressed Red flowers + White flowers = Incomplete Dominance: alleles blend

Multiple Alleles Defined: More then 2 alleles control a trait Ex: Blood Type has 3 alleles Dominant A allele Dominant B allele Recessive O allele A and B allele are equally codominant Codominant blood type

Ex: Cross Jason who is homozygous for type A blood with Maria who is homozygous for type B blood. List the genotypes. 100%AB List the phenotypes. 100% type AB blood B B A A B A B A B A B

Ex: Cross Mike who is heterozygous for type A blood with Lisa who is heterozygous for type B blood. List the genotypes. 25%AB 25%Ao 25%Bo 25%oo List the phenotypes. 25% type AB blood 25% type A blood 25% type B blood 25% type o blood Probability of Heterozygous individual? 75% B o A o A B A o B o o o