1. Exploring Mendelian Genetics

2. Question
Does the segregation of one pair of alleles affect the segregation of another pair of alleles?
Does the gene that determine hair color affect the gene for eye color?
Mendel preformed experiments to test this, and found that one does not affect the other.

3. Independent Assortment
Genes for different traits can segregate independently during the formation of gametes.
Two genes, like seed color and shape, do not influence each other’s inheritance.
Accounts for genetic variations in plants, animals, and other organisms.

4. Two-Factor Cross

5. Summary of Mendel’s Principles
Inheritance is determined by genes.
Genes have two alleles; one is dominate to the other.
Two copies of a gene, one from each parent.
When gametes are formed, the two alleles segregate.
Alleles for different genes segregate independently.

6. Mendel’s Principles Don’t Always Apply
Some alleles are neither dominant or recessive.
Many traits are controlled by multiple alleles or genes.
Can you think of any examples?

7. Incomplete Dominance
When one allele is not completely dominate over another.
The heterozygous phenotype is in between the two homozygous phenotypes.

8. Codominance
Both alleles appear in the phenotype.

9. Multiple Alleles & Polygenic Traits
Multiple Alleles: trait has more than two possible alleles. Organism will only have two alleles for the trait.
rabbit hair color & human blood type
Polygenic Traits: traits controlled by two or more genes.
skin color, eye color, height

10. Multiple Alleles

11. Polygenic Trait: Eye Color