1. Incomplete Dominance
&
Codominance

2. 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

3. 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

4. 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

5. 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

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

7. 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

8. 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

9. 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