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Lecture 29

Lecture 29. Inheritance. Importance of genetics. Understanding hereditary diseases and to develop new treatments Donor matches Paternity Forensics Evolution. Genetic Testing. Would you want to know? Ethical concerns Cost Insurance companies see. Difference between Meiosis and Mitosis.

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Lecture 29

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  1. Lecture 29 Inheritance

  2. Importance of genetics • Understanding hereditary diseases and to develop new treatments • Donor matches • Paternity • Forensics • Evolution

  3. Genetic Testing • Would you want to know? • Ethical concerns • Cost • Insurance companies • see

  4. Difference between Meiosis and Mitosis

  5. Meiosis I Interphase Prophase I Metaphase I Anaphase I Telephase I

  6. Crossing Over of Nonsister Chromatids between Homologous Chromosomes

  7. Meiosis II Prophase II Metaphase II Anaphase II Telephase II

  8. Genetic Testing

  9. Gel electrophoresis

  10. Polymerase Chain Reaction PCR is a rapid, inexpensive and simple way of copying specific DNA fragments from minute quantities of source DNA material Three steps are involved in PCR: denaturation, annealing and extension

  11. Genetic Testing $299, looks at specific diseases Paternity Test $99

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

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

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

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

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

  17. 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

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

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

  20. Homologous Chromosomes gene: location allele: specific trait

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

  22. Allele Examples appearance eye color:homozygous

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

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

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

  26. PKU Each parent carries one gene for PKU. P p P P P P p P p X P p P p p p p Possible genotypes: 1PP 2Pp 1pp Possible phenotypes:no PKU PKU

  27. Compare this to what would have happened if one parent was homozygous for sickle cell. HbA HbA HbA HbA HbS HbA HbA HbS HbS X HbA HbA HbS HbS HbS HbS HbS all offspring are carriers of sickle cell trait

  28. Autosomes and Sex Chromosomes

  29. Red-Green Color Blindness Sex-linked trait XC Y XC Y XC XC XC Normal male XC Y X XC Xc XC Xc Xc Xc Y Normal female recessive gene Possible outcomes: XCXC XCXc XCY XcY Normal female Normal Female (carrier) Normal male Color-blind male

  30. Dominance Most traits show complete dominance Blending unexpected

  31. allele gene E unconnected earlobe e connected earlobe P EE x ee E e gametes F1 Ee

  32. F1 Ee x Ee 1/2 E 1/2 e1/2 E 1/2 e gametes E e E EE Ee PunnettSquare e Ee ee F2 1 EE 2 Ee 1 ee

  33. generation genotypes unconnected E:e P EE, ee 50% 1:1 F1 Ee 100% 1:1 F2 EE, 2 Ee, ee 75% 1:1 phenotypes ratio of alleles in the population Basis of the Castle-Hardy-Weinberg Law

  34. Genotypes Phenotypes Experiment to determinedominant vs. recessive

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

  36. Pedigree phenotypes infer genotypes Alternative: look directly at the DNA

  37. Complexities • Multiple genes for one trait • Example: eye color • Blended traits (“incomplete dominance”) • Influence of the environment

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

  39. Human Genetic Traits

  40. Tongue Roller R = Tongue Rollerr = Unable to Roll Tongue

  41. Widow’s Peak W = Widows Peakw = Lack of Widow’s Peak

  42. Attached Ear Lobe Free Ear Lobe E = Free Ear Lobee = Attached Ear Lobe

  43. Hitchhiker’s Thumb Hi = Straight Thumbhi = Hitchhiker’s Thumb

  44. Bent Little Finger Bf = Bent Little Fingerbf = Straight Little Finger

  45. Mid-digital Hair M = Mid-Digital Hairm = Absence of Mid-Digital Hair

  46. Dimples D = Dimplesd = Absence of Dimples

  47. Short Hallux Ha = Short Halluxha = Long Hallux

  48. Short Index Finger Ss = Short Index FingerS1 = Long Index Finger *Sex-Influenced Trait

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