Unit 3 – Genetics

1. Unit 3 – Genetics • Today’s agenda: • Warm up • Practice correction • Power point presentation/notes I can explain the relationships between DNA and chromosomes and explain how traits are passed from parents to offspring

2. Warm up • Copy these words on a sheet of paper, then connect them and explain your connections DNA, nucleus, cell, fertilization, mitosis, DNA replication, chromosomes, genes, chromatids, karyotypes, diploid cells, haploid cells, gametes

3. Warm up • Identify the structures labeled X and Y If a cell has 8 chromosomes, how many chromatids does it have? What are haploid and diploid cells? (give examples and indicate numbers of chromosomes per each) What is the name of structures A and B?

4. Hook Try to roll your tongue. Can you?

5. These women are twins. What questions come to mind?

6. Prior knowledge What are genes? What is this picture representing? Where is DNA found? What are chromosomes?

7. Genes and Traits Genetics is the study of how traits are passed from parents to offspring.Traits are physical characteristics and they are determined by the genes on the chromosomes. A gene is a segment of DNA that determines a trait. http://learn.genetics.utah.edu/content/basics/traits/

8. Genes vs. Traits • GENOTYPE: combination of genes an organism • PHENOTYPE: Physical appearance resulting from gene make-up

9. What do the words dominant and recessive mean? http://www.youtube.com/watch?v=EIy8AzwKFZE

10. What is the difference between a gene and an allele? https://www.youtube.com/watch?v=F09kUKWSvAQ

11. Genes Gene: location Allele: alternative form of a gene • Homologous chromosomes: one from mom and one from dad. • We indicate genes with letters

12. Warm up • Define the following terms: • Homologous chromosomes • Homozygous dominant • Homozygous recessive • Heterozygous

13. Allele Example • Gene = “eye color” • Alleles • Brown (B) • Blue (b) • green • lavender

14. Allele Examples Appearance: brown B B Homozygous: Term used to refer to an organism that has two identical alleles for a particular trait (BB)

15. Allele Examples Appearance: brown (brown dominant over blue) B b Heterozygous - Term used to refer to an organism that has two different alleles for the same trait (Bb)

16. Allele Examples ? b b

17. Allele Examples Appearance: blue b b Homozygous- Term used to refer to an organism that has two identical alleles for the same trait (bb)

18. Genotype vs Phenotype genotype phenotype Homozygous(dominant) Heterozygous Homozygous (recessive) B B b B b b appearance https://www.youtube.com/watch?v=D8Nu3Aw6F2A https://www.youtube.com/watch?v=NLVulUy7T7E

19. You do Straight thumb is dominant to hitchhiker thumb. How can you express this concept in genetics? Use the letter “T” for this trait

20. Example: Straight thumb is dominant to hitchhiker thumb T= straight thumb t= hitchhikers thumb Straight thumb = TT Straight thumb = Tt Hitchhikers thumb = tt * Must have 2 recessive allelesfor a recessive trait to “show”

21. Warm up Can an individual heterozygous for brown eyes pass on to his children the gene for blue eyes? Explain. Why in the Punnet Square the parents are expressed with 2 letters (why not just one letter?)?

22. Practice A woman with red hair marries and has kids with a man with dark brown hair (see picture ). Dark brown hair trait is dominant over red hair trait. What color would their child’s hair be? Explain.

23. Messi and his family: predict their child’s traits

24. Messi + Roccuzzo

25. If Messi married and had a child with Lawrence what would have been their child’s traits?

26. Punnett Square If male & female are heterozygous for eye color male b B B b B B B b B female X B b b b b B b GenotypeBB 1/4 offspring (25%) Bb: 2/4 offspring (50%) bb: 1/4 offspring (25%) Phenotypebrown: 3/4 offspring (75%) blue: 1/4 offspring (25%)

27. Practice #1 Punnett squares are used by geneticists to determine the probability of different offspring genotypes. In the one shown below, what letter(s) belong in the lower right box?

28. Practice #2 If two parents are heterozygous for a genetically inherited dominant trait, what is the probability that they will have a child together who has this trait in his or her phenotype?

29. Practice #3 Black fur(B) in guinea pigs is dominant over white fur(b). Find the probability of an offspring with the same phenotype as its parents in a cross between a homozygous dominant and a heterozygous guinea pig

30. Interpreting diagrams: Phenotype vs Genotype

31. Phenotype vs Genotype

32. Phenotype vs Genotype

33. Warm up #1 In rabbits, black fur is dominant to white fur. If you cross a BB male with a Bb female, what are the possible genotypes and phenotypes of the offspring? What is the percent chance for each type? Include genotypic and phenotypic ratios.

34. Warm up #2 • In cabbage butterflies, White wings are dominant to yellow wings. If a Wwbutterfly is crossed with a wwbutterfly, what are the possible genotypes and phenotypes of the offspring and the percent chance for each? Include genotypic and phenotypic ratios.

35. Warm up #3 In guinea pigs, long hair is dominant to short hair. A pure bred short haired guinea pig is bred with a hybrid long haired. What does each of those look like? (use H)

36. Warm upWhich set of fruit flies are most likely the offspring’s parents? WHY? Offspring Parents B Parents A Parents C Parents D

37. Discussion questions Offspring What traits does the offspring have? Dominant genes will always present themselves in the offspring, and recessive genes only present themselves if dominant genes are not present. What might be the dominant and recessive genes of parents B? What might be the dominant and recessive genes of Parents D? Parents A Parents C Parents D Parents B

38. Check your understanding The following alleles AA are • Dominant • Recessive • Heterozygous • Homozygous dominant

39. Check your understanding Heredity is • The study of how people reproduce • The study of germ cells • The study of how people inherit traits • The study of peas

40. Check your understanding A trait is • A different form of a gene • A special gene • A physical characteristic • None of above

41. Check your understanding If you look at someone you will be able to see his or her genotype • True • False

42. Check your understanding Let’s assume you have brown eyes. Is it possible that you are carrying the gene for blue eyes? No, otherwise I would have blue eyes No, I only carry one allele for that trait Yes, the allele for brown eyes is dominant Yes, the allele for blue eyes is dominant None of above

43. Genetics song http://www.youtube.com/watch?v=54wxJ6E_2K8

44. Warm up In dogs, the gene that codes for dark fur is dominant over light fur. A hybrid dark fur is bred with a hybrid light fur. Calculate the genotype and phenotype ratios.

45. Problem: Justify Think-Pair-Share A purple flower could either homozygous (PP) or heterozygous for pea color (Pp). How can you test it? PP or Pp??

46. Would any of these crosses be useful? Why? X X

47. Testcross A testcross is a cross between an organism with an unknown genotype (FF or Ff) and an organism with the recessive phenotype (ff) ? ?

48. Testcross A testcross is a cross between an organism with an unknown genotype (FF or Ff) and an organism with the recessive phenotype (ff) F f

49. Let’s practice more A plant with yellow pea could either be homozygous (YY) or heterozygous for pea color (Yy). How can you test it? YY or Yy

50. Problem – Justify Think-Pair-Share Omar, a healthy man, marries Jen, a healthy woman. Their son has a genetic disease and he is homozygous recessive for the disease. How is it possible that Omar and Jen do not have the disease? Why they do not show any symptom?