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Medical Genetics

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Medical Genetics

  1. 1. Medical Genetics www.freelivedoctor.com
  2. 2. Mitosis <ul><li>Produces daughter cells with 46 chromosomes </li></ul><ul><li>Used in growth and repair </li></ul>www.freelivedoctor.com
  3. 3. Mitosis <ul><li>DNA is duplicated </li></ul><ul><li>Doubled chromosomes form from duplicated DNA </li></ul><ul><li>Each cms has 2 identical chromatids </li></ul>www.freelivedoctor.com Chromatid Chromatid
  4. 4. Chromosomes line up in a single row. Mitosis Metaphase www.freelivedoctor.com
  5. 5. Chromosomes separate Each chromatid becomes a single chromosome www.freelivedoctor.com
  6. 6. Meiosis <ul><li>Reduce the chromosome number to half that of body cells </li></ul><ul><li>Produce gametes </li></ul><ul><ul><li>Egg </li></ul></ul><ul><ul><li>Sperm </li></ul></ul>www.freelivedoctor.com
  7. 7. Chromosomes line up in a double row. Meiosis Metaphase www.freelivedoctor.com
  8. 8. Chromosomes separate Each each daughter cell gets doubled chromosomes www.freelivedoctor.com
  9. 9. Doubled Chromosomes Separate in Second Meiotic Division www.freelivedoctor.com
  10. 10. www.freelivedoctor.com Mitosis Metaphase Meiosis Metaphase
  11. 11. Double Filed Chromosomes <ul><li>Daughter cells receive ONE of each cms pair </li></ul><ul><li>Daughter cells receive ONE allele for most traits </li></ul><ul><li>New combinations of alleles possible </li></ul>www.freelivedoctor.com Cms 1 Cms 1 Cms 2 Cms 2
  12. 12. Gene <ul><li>A unit of heredity that controls the development of one trait </li></ul><ul><li>Made of DNA </li></ul>www.freelivedoctor.com
  13. 13. Allele <ul><li>Member of a paired gene </li></ul><ul><ul><li>One allele comes from each parent </li></ul></ul><ul><li>Represented by a single letter </li></ul>www.freelivedoctor.com
  14. 14. Examples of Alleles Dwarfism = D Normal height = d DD = Dwarfism Dd = Dwarfism dd = Normal height www.freelivedoctor.com Dwarf Band
  15. 15. Dominant & Recessive Alleles <ul><li>Dominant alleles are expressed </li></ul><ul><li>Recessive alleles are not expressed in the presence of a dominant allele </li></ul><ul><ul><li>Recessive alleles are only expressed if both recessive alleles are present </li></ul></ul>www.freelivedoctor.com
  16. 16. Homozygous <ul><li>Both alleles alike </li></ul><ul><li>AA or aa </li></ul>www.freelivedoctor.com
  17. 17. Heterozygous <ul><li>Alleles are different </li></ul><ul><li>Aa </li></ul>www.freelivedoctor.com
  18. 18. Genotype <ul><li>Genetic make up </li></ul><ul><li>Represented by alleles </li></ul><ul><li>DD & Dd are genotypes for dwarfism </li></ul>www.freelivedoctor.com
  19. 19. Phenotype <ul><li>A trait </li></ul><ul><li>Genotype determines the phenotype </li></ul><ul><li>Dwarfism is a phenotype </li></ul>www.freelivedoctor.com
  20. 20. Codominant <ul><li>Two different alleles are both dominant </li></ul><ul><li>A = allele for type A blood </li></ul><ul><li>B = allele for type B blood </li></ul><ul><li>AB = results in type AB blood </li></ul>www.freelivedoctor.com
  21. 21. Karyotype <ul><li>Picture of chromosomes from an individual </li></ul>www.freelivedoctor.com
  22. 22. Homologous Chromosomes <ul><li>Chromosomes of the same pair </li></ul><ul><li>Karyotypes are usually arranged with homologous chromosomes paired together </li></ul>www.freelivedoctor.com
  23. 23. Mutation <ul><li>Change in a gene or chromosome </li></ul><ul><li>Causes an abnormal trait </li></ul>www.freelivedoctor.com
  24. 24. Mutagen Agent that causes mutations www.freelivedoctor.com Cigarette smoke Pesticides X-rays Ulatraviolet light Nuclear radiation
  25. 25. Homologous chromosomes line up in a double file in metaphase I of meiosis www.freelivedoctor.com
  26. 26. Homologous Pairs Separate www.freelivedoctor.com
  27. 27. Four Gametes With Single Chromosomes www.freelivedoctor.com
  28. 28. Fertilization www.freelivedoctor.com
  29. 29. Nondisjunction www.freelivedoctor.com
  30. 30. Trisomy www.freelivedoctor.com
  31. 31. Sex Chromosomes www.freelivedoctor.com
  32. 32. Sex Chromosomes <ul><li>Male have Xy </li></ul><ul><ul><li>Male gametes have either X or y </li></ul></ul><ul><li>Females have XX </li></ul><ul><ul><li>Female gametes have X </li></ul></ul>www.freelivedoctor.com
  33. 33. Autosomes Chromosomes 1-22 www.freelivedoctor.com
  34. 34. X-Linked Traits <ul><li>Alleles are on the X chromosome </li></ul><ul><li>Females have two alleles </li></ul><ul><li>Males have one allele </li></ul><ul><ul><li>Only one X chromosome </li></ul></ul>www.freelivedoctor.com
  35. 35. Normal Male www.freelivedoctor.com
  36. 36. Normal Female www.freelivedoctor.com
  37. 37. Trisomy 21 Down Syndrome www.freelivedoctor.com
  38. 38. Down Syndrome <ul><li>Large tongue </li></ul><ul><li>Flat face </li></ul><ul><li>Slanted eyes </li></ul><ul><li>Single crease across palm </li></ul><ul><li>Mental retardation </li></ul><ul><ul><li>Some are not </li></ul></ul>www.freelivedoctor.com
  39. 39. Maternal Age & Down Syndrome www.freelivedoctor.com
  40. 40. Trisomy 18 Edward Syndrome www.freelivedoctor.com
  41. 41. Edward Syndrome <ul><li>Heart defects </li></ul><ul><li>Displaced liver </li></ul><ul><li>Low-set ears </li></ul><ul><li>Abnormal hands </li></ul><ul><li>Severe retardation </li></ul><ul><li>98% abort </li></ul><ul><li>Lifespan < 1 year </li></ul>www.freelivedoctor.com
  42. 42. Trisomy 13 Patau Syndrome www.freelivedoctor.com
  43. 43. Patau Syndrome <ul><li>Cleft lip and palate </li></ul><ul><li>Extra fingers & toes </li></ul><ul><ul><li>polydactylism </li></ul></ul><ul><li>Defects </li></ul><ul><ul><li>Heart </li></ul></ul><ul><ul><li>Brain </li></ul></ul><ul><ul><li>Kidneys </li></ul></ul><ul><li>Most abort </li></ul><ul><li>Live span < 1 month </li></ul>www.freelivedoctor.com
  44. 44. Klinefelter Syndrome www.freelivedoctor.com
  45. 45. Klinefelter Syndrome <ul><li>Breast development </li></ul><ul><li>Small testes </li></ul><ul><li>Sterile </li></ul><ul><li>Low intelligence </li></ul><ul><ul><li>Not retarded </li></ul></ul>www.freelivedoctor.com Klinefelter Website
  46. 46. Turner Syndrome www.freelivedoctor.com
  47. 47. Turner Syndrome <ul><li>Short </li></ul><ul><li>Not go through pruberty </li></ul><ul><li>Produce little estrogen </li></ul><ul><li>Sterile </li></ul><ul><li>Extra skin on neck </li></ul>www.freelivedoctor.com
  48. 48. Fetal Testing www.freelivedoctor.com
  49. 49. Sickle Cell Anemia <ul><li>RBCs sickle shaped </li></ul><ul><li>Anemia </li></ul><ul><li>Pain </li></ul><ul><li>Stroke </li></ul><ul><li>Leg ulcers </li></ul><ul><li>Jaundice </li></ul><ul><li>Gall stones </li></ul><ul><li>Spleen, kidneys & lungs </li></ul>www.freelivedoctor.com
  50. 50. Sickle Cell Anemia <ul><li>Recessive allele, s codes for hemoglobin S </li></ul><ul><ul><li>Long rod-like molecules </li></ul></ul><ul><ul><li>Stretches RBC into sickle shape </li></ul></ul><ul><li>Homozygous recessive, ss have sickle cell anemia </li></ul><ul><li>Heterozygous, Ss are carriers </li></ul>www.freelivedoctor.com
  51. 51. Hemophilia <ul><li>Blood clotting impaired </li></ul><ul><li>Recessive allele, h </li></ul><ul><li>carried on X cms </li></ul><ul><li>X-linked recessive trait </li></ul><ul><li>More common in males </li></ul>www.freelivedoctor.com
  52. 52. Albinism <ul><li>Lack of pigment </li></ul><ul><ul><li>Skin </li></ul></ul><ul><ul><li>Hair </li></ul></ul><ul><ul><li>Eyes </li></ul></ul>www.freelivedoctor.com
  53. 53. Amino Acids Melanin Pigment Enzyme www.freelivedoctor.com A a AA = Normal pigmentation Aa = Normal pigmentation aa = Albino
  54. 54. PKU Disease <ul><li>Phenylalanine excess </li></ul><ul><li>Mental retardation if untreated </li></ul>www.freelivedoctor.com Molly’s Story
  55. 55. Phenylalanine Tyrosine Enzyme www.freelivedoctor.com P p PP = Normal Pp = Normal pp = PKU
  56. 56. A man & woman are both carriers (heterozygous) for albinism. What is the chance their children will inherit albinism? www.freelivedoctor.com
  57. 57. Man = Aa Woman = Aa www.freelivedoctor.com AA = Normal pigmentation Aa = Normal pigmentation (carrier) aa = Abino A a a A
  58. 58. AA Aa Aa aa www.freelivedoctor.com A a a A
  59. 59. Genotypes 1 AA, 2Aa, 1aa Phenotypes 3 Normal 1 Albino Probability 25% for albinism www.freelivedoctor.com AA Aa Aa aa
  60. 60. A man & woman are both carriers (heterozygous) for PKU disease. What is the chance their children will inherit PKU disease? www.freelivedoctor.com
  61. 61. p p P P www.freelivedoctor.com PP P p P p pp PP = Normal Pp = Normal (carrier) pp = PKU disease
  62. 62. Genotypes 1 PP, 2Pp, 1pp Phenotypes 3 Normal 1 PKU disease Probability 25% for PKU disease www.freelivedoctor.com PP Pp Pp pp
  63. 63. A man with sickle cell anemia marries a woman who is a carrier. What is the chance their children will inherit sickle cell anemia? www.freelivedoctor.com
  64. 64. s s s S www.freelivedoctor.com Ss Ss ss ss SS = Normal Ss = Normal (carrier) ss = Sickle Cell
  65. 65. Genotypes 2 Ss, 2ss Phenotypes 2 Normal (carriers) 2 Sickle cell Probability 50% for Sickle cell www.freelivedoctor.com Ss Ss ss ss
  66. 66. A man with heterozygous dwarfism marries a woman who has normal height. What is the chance their children will inherit dwarfism? Dwarfism is dominant. www.freelivedoctor.com
  67. 67. d d D d www.freelivedoctor.com Dd dd Dd dd DD = Dwarf Dd = Dwarf dd = Normal
  68. 68. Genotypes 2 Dd, 2dd Phenotypes 2 Normal 2 Dwarfs Probability 50% for Dwarfism www.freelivedoctor.com Dd dd Dd dd
  69. 69. X-linked Recessive Traits <ul><li>Alleles are on the X chromosome </li></ul><ul><li>Inheritance pattern different in males and females </li></ul>www.freelivedoctor.com
  70. 70. www.freelivedoctor.com X H X H = Normal Female X H X h = Normal Female (Carrier) X h X h = Hemophilic Female X H y = Normal Male X h y = Hemophiliac Male
  71. 71. A man with hemophilia marries a normal woman who is not a carrier. What is the chance their children will inherit hemophilia? Hemophilia is X-linked recessive. www.freelivedoctor.com
  72. 72. y X H X h X H X h X H X H X h X H y X H y www.freelivedoctor.com X h X H = Normal Female X H X h = Normal Female (Carrier) X h X h = Hemophilic Female X H y = Normal Male X h y = Hemophiliac Male
  73. 73. Genotypes 2 X H X h , 2 X H y Phenotypes 2 Carrier Females 2 Normal Males Probability O% for Hemophilia www.freelivedoctor.com y X H X h X H X h X H X H X h X H y X H y
  74. 74. A normal man marries a normal woman who is a carrier for hemophilia. What is the chance their children will inherit hemophilia? www.freelivedoctor.com
  75. 75. y X h X H X H www.freelivedoctor.com X h X H = Normal Female X H X h = Normal Female (Carrier) X h X h = Hemophilic Female X H y = Normal Male X h y = Hemophiliac Male X H X H X H X h X H y X h y
  76. 76. Genotypes X H X H , X H X h, X H y, X h y Phenotypes 2 Normal Females 1 Normal Males 1 Male Hemophiliac Probability 50% for Male Hemophilic 0% for Female Hemophilic y X h X H X H X H X H X H X h X H y X h y www.freelivedoctor.com
  77. 77. The End www.freelivedoctor.com

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