1. DNA Lecture 009

2. Gregor Mendel

3. Rosalind FranklinFrances Crick & James Watson X-ray diffraction photograph of DNA, 1953 Proposed double helix model 1953

4. Cell

5. Nucleus

6. DNA

7. What is DNA? DNA, or deoxyribonucleic acid, is the genetic instruction set. It is composed of a linear sequence of units called nucleotides. There are four different kinds of nucleotides (designated by the letters A, G, C, & T; sometimes called “bases”). An individual DNA strand (or chromosome) may consist of 100,000’s of nucleotides. The sequence of the nucleotides of a DNA strand determines the genetic code.

8. Polymers made up of individual nucleotides Nucleotides contain Phosphate group Five carbon sugar Ring shaped nitrogen base DNA contains information for almost all cell activities

9. Nitrogen Base

10. adenineguanine Purines

11. cytosine thymine Pyrimidines

12. Deoxyribose

14. DNA is Double Stranded

15. Base Pairing in DNA

18. Chromosomes

19. Chromosomes Come in Pairs

20. Beliefs about Heredity Fig. 1. De la propagation du genre humain, ou manuel indispensable pour ceux qui veulent avoir de beaux enfants de l’un ou l’autre sexe (Paris, Year VII). Image courtesy of the Bibliothèque Interuniversitaire de Médecine, Paris.

21. Homunculus How is “heredity passed on: Spermist vs Ovists Spermist conception of a human sperm

22. Homunculus Leeuwenhoek’s black male and white female rabbit experiments: spermist “proof”

23. Darwin What he got right.What he got wrong. Acquired characteristics Ex. Blind cave animals Sex. Repro.- gemmules from all over body are packed in sperm and egg Blended inheritance Likes produce likes Change can be permanent There is no limit to cumulative change

24. Mendel’s Three Principles Dominance Segregation Independent Assortment The foundation of “classical” science (1822-1884)

25. Genes- genetic material on a chromosome that codes for a specific trait Genotype- the genetic makeup of the organism Phenotype- the expressed trait Allel- an alternative form of a gene Genetic Definitions

26. Dominance Mechanism Two alleles are carried for each trait In true-breeding individuals, both alleles are the same (homozygous). Hybrids, on the other hand, have one of each kind of allele (heterozygous). One trait is dominant, the other trait is recessive

27. Dominance Traits of both parents inherited, but one shows over the other Traits are not blended

28. Segregation Half the gametes (egg or sperm) will carry the traits of one parent and half the traits for the other parent Pairs of alleles are separated (=segregated) during meiosis

29. Two different parental characteristics will be inherited independently of one another during gamete formation. Independent Assortment Example: flower color and leaf shape

30. Complexities Multiple genes for one trait Example: eye color Blended traits (“incomplete dominance”) Influence of the environment (UV, smoking, alcoholism)

31. Complexities Co-dominance-neither allele is recessive and the phenotypes of both alleles are expressed. Blood types- AB (not O); sickle cell anemia heterochromia

32. Disorders Down’s Syndrome (chrom 21) Huntington’s (chrom 4) Alzheimer’s (chrom 1, 10, 14, 19, 21)

33. Genetic Information Genes are traits “Eye color” Ear lobe connectedness Genes produce proteins Enzymes are proteins

34. Homologous Chromosomes allele: specific trait gene: location

35. Allele Example Gene = “eye color” Alleles brown blue green lavender

36. Allele Examples appearance eye color: homozygous

37. Allele Examples appearance eye color: heterozygous, brown dominant over blue

38. Genotype vs Phenotype homozygous (dominant) heterozygous homozygous (recessive) genotype phenotype appearance Phaner = visible

39. Punnett Square If male & female are heterozygous for eye color X brown:3/4 offspring blue:1/4 offspring male female

40. Sickle Cell Anemia Each parent carries one gene for sickle cell Ss Ss X S s sS S S S s s S s s Possible genotypes: 1SS 2Ss 1ss Possible phenotypes:no sickle cellsickle cell

41. Autosomes and Sex Chromosomes

42. Red-Green Color Blindness Sex-linked trait XCXC Y XCXC XcXc X XCXC XcXc YXCXC XCXC XCXC XCXC Y XcXc XCXC Y XcXc Normal male Normal female recessive gene Possible outcomes:X C X C X C X c X C YX c Y Normal female Normal Female (carrier) Normal male Color-blind male

43. Eunconnected earlobe econnected earlobe Eunconnected earlobe econnected earlobe allele gene PEE x ee gametes E e F1F1 unconnected connected

44. F1F1 Ee x Ee gametes 1/2 E 1/2 e E e Ee EEEe ee F2F2 1 EE 2 Ee 1 ee Punnett Square

45. Genotypes Phenotypes Experiment to determine dominant vs. recessive

46. Genetic Sleuthing My eye color phenotype is brown. What is my genotype?

47. Where Does Genetic Diversity Come From? MutationMutation Chromosomal AberrationsChromosomal Aberrations Genetic Recombination (e.g., from sexual reproduction)Genetic Recombination (e.g., from sexual reproduction)

48. mutation Sickle Cell Mutation CTG ACT CCT GAG GAG AAG TCT Leu Thr Pro Glu Glu Lys Ser CTG ACT CCT GAG GTG AAG TCT Leu Thr Pro Glu Val Lys Ser NORMAL Hb SICKLE CELL

49. Difference between Meiosis and Mitosis

50. Meiosis I Interphase Prophase IMetaphase IAnaphase ITelephase I

51. Crossing Over of Nonsister Chromatids between Homologous Chromosomes

52. Meiosis II Prophase IIMetaphase IIAnaphase IITelephase II

54. Genetic Testing

55. Predisposition to disease Alzheimer's case (Feb. 2002) Amniocentesis & Chorionic villa Family history >35 years old Donor match Paternity Forensics

56. Gel electrophoresis

57. PCR way of copying specific DNA fragments from small sample DNA material "molecular photocopying" It’s fast, inexpensive and simple Polymerase Chain Reaction

59. Genetic Testing Paternity Test $99 $299, looks at specific diseases 23 and me

60. Genetic Testing Would you want to know? Ethical concerns Cost Insurance companies

62. Tongue Roller R = Tongue Roller r = Unable to Roll Tongue

63. Widow’s Peak W = Widows Peak w = Lack of Widow’s Peak

64. Free Ear Lobe Attached Ear Lobe E = Free Ear Lobe e = Attached Ear Lobe

65. Hitchhiker’s Thumb Hi = Straight Thumb hi = Hitchhiker’s Thumb

66. Bent Little Finger Bf = Bent Little Finger bf = Straight Little Finger

67. Mid-digital Hair M = Mid-Digital Hair m = Absence of Mid-Digital Hair

68. Dimples D = Dimples d = Absence of Dimples

69. Short Hallux Ha = Short Hallux ha = Long Hallux

70. Short Index Finger S s = Short Index Finger S 1 = Long Index Finger *Sex-Influenced Trait

71. http://www.youtube.com/watc h?v=gCPuHzbb5hA