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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. 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

  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 way of copying specific DNA fragments from small sample DNA material "molecular photocopying" • It’s fast, inexpensive and simple

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

  12. Genetic Definitions • 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

  13. 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

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

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

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

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

  18. 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

  19. 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

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

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

  22. Homologous Chromosomes gene: location allele: specific trait

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

  24. Allele Examples appearance eye color:homozygous

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

  26. Genotype vs Phenotype genotype phenotype homozygous(dominant) heterozygous homozygous (recessive) appearance

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

  28. 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

  29. 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

  30. Where Does Genetic Diversity Come From? • Mutation • Chromosomal Aberrations • Genetic Recombination (e.g., from sexual reproduction)

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

  32. Autosomes and Sex Chromosomes

  33. 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

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

  35. 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

  36. Genotypes Phenotypes Experiment to determinedominant vs. recessive

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

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

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

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

  41. Human Genetic Traits

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

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

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

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

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

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

  48. Dimples D = Dimplesd = Absence of Dimples

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