1. Genetics of Hair Simple Trait, Complex Genetics

2. What determines our natural hair color?

3. ► Brunette ladies can give birth to blonde children if the father is blonde. (Can it happen if the father is brunette?) ► Brunette + Blonde parents = either hair color in children. (Does the sex of the parent matter?) ► Not really enough information in this pedigree to make strong conclusions

4. ► Brunette ladies can give birth to blonde children if the father is blonde. (Can it happen if the father is brunette?) ► Brunette + Blonde parents = either hair color in children. (Does the sex of the parent matter?) ► Not really enough information in this pedigree to make strong conclusions

6. Why use Model Organisms?

7. Purebred labrador breeding

8. After many breedings… ► Which phenotype is dominant?

9. Breeding F1 generation puppies ► Observations? ► Conclusions?

10. Homozygous dominant, Homozygous recessive or Heterozygous? ► TT ► Bb ► ee ► EE ► Ll ► PP ► Pp ► pp ► GG ► HH ► Hh ► Aa ► AA ► Oo ► oo ► aa

11. Practice ► Draw a Punnett square crossing TT and TT ► Draw a Punnett square crossing TT and Tt ► Draw a Punnett square crossing Tt and Tt ► Draw a Punnett square crossing tt and tt ► Draw a Punnett square crossing a homozygous dominant brown dog with a heterozygous brown dog

12. What is happening? ► Let’s review the parents… ► Dominant – an allele that is expressed in the heterozygous condition ► cross = breeding resulting in offspring ► Offspring ► Purebred ► P generation ► F 1 Generation

13. Fertilization

14. The gametes of the F1 gen… ► Gamete ► Fertilization ► Zygote ► Genotype ► Homozygous recessive ► Homozygous dominant ► Heterozygous

15. Punnett Squares

17. “Ask a Geneticist” ► Read the article and answer the post- reading questions. ► You will have 20-25 mins. Then we will hold a more detailed discussion on hair color. ► Hair color writing quiz on Wednesday!!!

18. Best explanation of a genetically dominant trait? (Poll everywhere) http://www.polleverywhere.com/multiple_choice_polls/qsv3ClzjmdZAcQs http://www.polleverywhere.com/multiple_choice_polls/qsv3ClzjmdZAcQs ► Most common in population ► Most beneficial trait available ► What appears when both parents have dominant trait ► What appears when an individual has two different genes for a trait ► What destroys the recessive trait

19. Are all hair colors just variations on brown?

20. What causes the reddish shades?

21. How hair grows: Hair Anatomy

23. My explanation for variations…

24. Melanocytes

25. Melanins ► Photoprotectant pigment in mammals.  Why would we want it??? ► Made by melanocytes in skin and hair follicles ► Eumelanin  Brown or black  Amount matters  4 pairs of genes  POLYGENIC ► Pheomelanin ► Red ► Scots/Irish ► MC1R gene ► Turns Ph  Eu

27. Chromosomes from 1 human cell

28. Locations of hair color genes

29. MC1R gene location & its function

30. Polygenic = controlled by multiple gene pairs

31. Why two types of Melanin? ► Which colors of hair are generally associated with very dark skin tones? Why is this?  advantage ?  geographic regions? ► Which skin tones are generally associated with red hair?  advantage ?  geographic regions?

32. What about albinos?

33. Why does hair turn gray?

35. What is melanoma?

36. Trying to change our phenotypes!

37. Hair Texture ► Totally different genes from hair color ► Curly and wavy hair is caused by disulfide bonds between the amino acid cysteine in the hair structure ► More cysteine = curlier

38. Polygenic = controlled by multiple gene pairs

39. 4) Polygenic traits ► Huge range of phenotypes due to influence of many gene pairs; falls along a bell curve

40. Polygenic – finch beak depth

41. Fig. 14-13 Eggs Sperm Phenotypes: Number of dark-skin alleles: 0 1 2 345 6 1 / 64 6 / 64 15 / 64 20 / 64 15 / 64 6 / 64 1 / 64 AaBbCc 

42. Polygenic - eye color

43. True or False? ► In sexual reproduction, one parent contributes genes for some characteristics, while the other features come from the other parent.

44. Cystic Fibrosis sample ► A child with CF is born to two parents without it. What do you know about the parents’ genotypes?