2. Simple Traits One gene pair Only two alleles Genotypes Phenotypes Examples

3. Multiple Alleles Three or more alleles Genotypes & phenotypes Human blood type 1. Alleles – A, B, O 2. One gene pair 3. A, B codominant – O recessive

4. How many possible genotypes are there for human blood type? How many possible phenotypes? Inheritance Problem #1

5. Polygenic Traits Definition Inherit more than two alleles/trait Parakeet color 1. Two gene pairs 2. Inherit 4 alleles Human examples

6. There are three alleles for parakeet feather color – blue, yellow and white. Inheritance Problem #2 Blue and yellow blend to green. (Incomplete dominance) White is recessive. Blue (B) Yellow (Y) White (b or y)

7. Inheritance Problem #2 How many possible phenotypes are there for feather color? How many possible genotypes?

8. Environmental Factors Influences outside the cells Himalayan rabbit Fruit flies Plants

9. Hormones Gene expression Male-pattern baldness Male and female birds