1. Simple Dominance One trait is completely dominant to the other
Punnett Squares
Simple Dominance
One trait is completely dominant to the other
If you have even one allele for the dominant trait, that trait will be visible

2. Punnett Squares
Incomplete Dominance
Heterozygous phenotype is between the two homozygous phenotypes
The phenotypes look like they blend

3. Codominance Both alleles contribute to the phenotype
Punnett Squares
Codominance
Both alleles contribute to the phenotype
Similar to incomplete dominance, but there is no mixing

4. Punnett Squares
Codominance in cows +

5. Polygenic Traits Polygenic is when many genes affect the phenotype
Punnett Squares
Polygenic Traits
Polygenic is when many genes affect the phenotype
Examples:
At least 3 genes are responsible for eye color in fruit flies and different combinations produce very different results
Skin color in humans is controlled by more than 4 different genes

6. Punnett Squares
Polygenic Traits

7. Eye Color is controlled by 2 genes = 4 alleles
Polygenic Traits
Eye Color is controlled by 2 genes = 4 alleles

8. Multiple Alleles
There are more than 2 alleles for a gene in a population of a species
A single organism has only 2 of the alleles, but more than 2 exist in the population

9. Multiple Alleles Example: human blood type alleles
There are 4 blood types:
A, B, AB, and O
3 alleles for blood type: IA, IB, i
Type A = IA IA or IAi
Type B = IB IB or IB i
Type AB = IA IB
Type O = ii
* IA and IB are codominant
* i is recessive to both IA and IB

10. Blood type is determined by which antigens (proteins) you have on your blood cells
If you are missing a certain antigen, the body developed antibodies that bind to the antigens if they encounter it.

11. Figure 14.10 Multiple alleles for the ABO blood groups
Punnett Squares 11

12. Punnett Squares
Blood Type 12