1. Incomplete Dominance & Codominance Section 11-3 in Book

2. Review of Mendel’s Principles Genes are passed parents  offspring; get one allele from each parent During Meiosis, the alleles for a gene segregate from each other. During Meiosis, genes independently assort with each other.

3. Exceptions to Mendel’s principles Sometimes, there is no dominant or recessive gene, or the trait is controlled by many alleles or genes.

4. Neither allele is dominant Heterozygous phenotype produces 3 rd phenotype somewhere between homozygous phenotype. Incomplete Dominance

5. 1. Incomplete Dominance Examples: Trait: Flower Color Expressions: Red x White  Pink RR= Red; RW= pink; WW= white straight hair, wavy, curly

6. Incomplete Dominance

7. In codominance, both alleles are dominant and are expressed in heterozygous organisms. Codominance

8. 2. Codominance Both alleles contribute to the phenotype.  Example: In come chickens Black Chicken x White  Speckled Chicken

9. YOU tell me which type of dominance… Codominance!

11. Type of Dominance? Incomplete Dominance!

12. Type of Dominance? Incomplete Dominance!

13. Multiple Alleles Gene has more than two alleles. Ex. Blood type in humans

15. Polygenic Traits Trait controlled by two or more genes  Ex. Skin color of humans (4 different genes)  Reddish-brown eyes of fruit flies

16. Sex-Linked Genes/Traits Special pattern of inheritance for genes located on the X and Y chromosomes. Y chromosome is very small only holds a few genes

17. 3 human genes associated with color vision are on the X chromosome. In males, a defected version of these genes produces colorblindness.

18. Why the difference? Males only have one X chromosome.

20. Pedigree