1. DNA – March 15, 2011 1.What is one example of a genetic disease? Describe it. 2.Show the cross between a Mom who is heterozygous for polydactyl and a Dad who is homozygous recessive for polydactyl. 3.Using your cross from question 2, what is the probability that the offspring will have more than 5 fingers? What is the probability the offspring will be heterozygous?

2. Today’s Objective SWBAT – Understand the difference between codominance and incomplete dominance

3. Incomplete Dominance Neither of the alleles is dominant to the other. – The phenotype of the offspring is a mixture of the two phenotypes of the parents. This results in a BRAND new phenotype – Example: Yellow Cow + Blue Cow = Green Cow

4. Example: Skin Color

5. Codominance The phenotype of the offspring is a combination of the phenotypes of both parents. Both alleles are expressed separately and contribute to the offspring’s appearance (Unrealistic) Example: – Striped elephant + a polka dot elephant = striped & polka-dot elephant

6. Example - Chickens A black-feathered (BB) chicken crossed with a white-feathered (WW) chicken results in a black and white feathered chicken (BW).

7. Show the Cross - Codominance If a black chicken (BB) and a white chicken (WW) mate, what is that probability that the baby chicken will be black? White? Mixture? What happens if a black and white chicken (BW) mates with another black and white chicken? What is the phenotypic ratio?

9. Incomplete Dominance?

10. Codominance?

13. Incomplete Dominance?

15. Codominance?

16. Incomplete Dominance?

17. Practice Problems Incomplete dominance: B = Black, W = White 1.A black female dog and a white male dog have a litter of puppies. If they have 4 puppies, what does probability predict about the phenotypes of these puppies?

18. Practice Problems Codominance: R = Red, Y = Yellow 2.A female orange panda mates with a male yellow panda. Show the cross and give the phenotypic and genotypic ratios.