Incomplete Dominance & Codominance

1. Incomplete Dominance & Codominance

2. Codominance red • 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 white roan

3. Human blood type has 3 alleles Dominant A allele Dominant B allele Recessive O allele A and B allele are equally codominant Blood Types Codominant blood type

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

5. 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% Ex: Mike is heterozygous for type A blood and Lisa is heterozygous for type B blood. B o A o A B A o B o o o

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

7. List the genotypes possible. 100% RW List the phenotypes possible. 100% Pink Example: Cross an incomplete homozygous dominant red carnation (RR) with an incomplete homozygous white carnation (WW). W W R W R W R R pink pink R W R W pink pink

8. List the genotypes possible. 50% RW 50% WW List the phenotypes possible. 50%Pink 50%White Example: Cross one heterozygous pink (RW) carnation with a white carnation (WW). R W R W W W W W pink white R W W W pink white

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