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  1. 1. Gene, chromosome,DNA DNA
  2. 2. Patterns of Inheritance <ul><li>Complete Dominance </li></ul><ul><li>Incomplete Dominance </li></ul><ul><li>Codominance </li></ul><ul><li>Pleitrophy </li></ul><ul><li>Epistasis </li></ul><ul><li>Multiple Alleles </li></ul><ul><li>Polygenic </li></ul><ul><li>Sex Linked </li></ul><ul><li>Sex influenced </li></ul><ul><li>multifactorial </li></ul>
  3. 3. Blending theory <ul><li>Genetic materials are like liquids </li></ul><ul><li>Particulate theory </li></ul><ul><li>Hereditary units are discrete units or genes </li></ul>
  4. 4. Mendel <ul><li>Made genetics quantifiable </li></ul><ul><li>Experimental crosses </li></ul><ul><li>Character- detectable inherited feature </li></ul><ul><li>Trait-variation of a character </li></ul>
  5. 5. <ul><li>True breeding or pure bred- always produced the same trait </li></ul><ul><li>Hybrids produced different variants </li></ul><ul><li>WHY </li></ul>
  6. 7. Nature vs Nurture <ul><li>What role is played by genetics? </li></ul><ul><li>What role is played by the environment? </li></ul>
  7. 8. A a AA aa a a A A a a A A Gametes (A,a) segregate
  8. 9. Principles of Heredity <ul><li>Alternative versions of genes (alleles) account for variations in a trait. </li></ul><ul><li>For each character, an organism inherits two alleles, one from each parent. </li></ul><ul><li>If alleles differ, then the dominant will be fully expressed over the recessive. </li></ul><ul><li>The two alleles segregate (separate) during gamete formation. </li></ul><ul><li>Alleles on different chromosomes segregate independently of one another </li></ul>
  9. 10. <ul><li>A </li></ul><ul><li>a </li></ul><ul><li>B </li></ul><ul><li>b </li></ul><ul><li>Independent Assortment and Segregation </li></ul><ul><li>For an organism of the genotype AaBb </li></ul>
  10. 11. <ul><li>Meiosis results in the following: </li></ul>
  11. 12. <ul><li>a </li></ul><ul><li>A </li></ul><ul><li>b </li></ul><ul><li>B </li></ul><ul><li>Independent Assortment and Segregation </li></ul><ul><li>For an organism of the genotype AaBb </li></ul><ul><li>ab </li></ul><ul><li>AB </li></ul>
  12. 13. <ul><li>A </li></ul><ul><li>a </li></ul><ul><li>B </li></ul><ul><li>b </li></ul><ul><li>Independent Assortment and Segregation </li></ul><ul><li>For an organism of the genotype AaBb </li></ul><ul><li>AB </li></ul><ul><li>ab </li></ul>
  13. 14. <ul><li>a </li></ul><ul><li>A </li></ul><ul><li>B </li></ul><ul><li>b </li></ul><ul><li>Independent Assortment and Segregation </li></ul><ul><li>For an organism of the genotype AaBb </li></ul><ul><li>aB </li></ul><ul><li>Ab </li></ul>
  14. 15. <ul><li>a </li></ul><ul><li>A </li></ul><ul><li>b </li></ul><ul><li>B </li></ul><ul><li>Independent Assortment and Segregation </li></ul><ul><li>For an organism of the genotype AaBb </li></ul><ul><li>ab </li></ul><ul><li>AB </li></ul>
  15. 16. Calculate the posssible gametes from the following crosses BbHh, DDHh, BbDd, bbhh <ul><li>BH, Bh, bH, bh </li></ul><ul><li>DH,Dh </li></ul><ul><li>BD, Bd, bD, bd </li></ul><ul><li>bh </li></ul>
  16. 17. Genetic Crosses and Problems <ul><li>Monohybrid </li></ul><ul><li>Dihybrid </li></ul><ul><li>Pedigree </li></ul>
  17. 18. Monohybrid Cross-consider only one trait Offspring F1 Gametes Gametes
  18. 19. Monohybrid Cross-consider only one trait Offspring F2 Gametes Gametes Genotypic ratio 1 : 2 : 1 Phenotypic ratio 3 : 1
  19. 20. Law of Multiplication of Probabilities <ul><li>Bb ½ B or ½ b </li></ul><ul><li>XBb ½ B or ½ b </li></ul><ul><li>1/4BB + 1/2Bb + ¼ bb </li></ul>
  20. 21. <ul><li>BB ½ B or ½ B </li></ul><ul><li>XBb ½ B or ½ b </li></ul><ul><li>½ BB + ½ Bb </li></ul>
  21. 22. Dihybrid cross-cross two traits heterozygous black wings BbWw X BbWw Phenotypic Ratio 9:3:3:1
  22. 23. Crossing over During prophase of meiosis homologous pairs may exchange genetic material. <ul><li>TETRAD or synapsis </li></ul>
  23. 25. New Genetic Combinations <ul><li>Recombination during fertilization brings together two sets of genetic instructions </li></ul><ul><li>Meiosis-crossing over brings about new combinations </li></ul><ul><li>Random genetic mutation can result in random genetic change </li></ul>
  24. 26. Autosomal Complete Dominance <ul><li>One gene is able to dominate the other recessive allele </li></ul><ul><li>Example all offspring express B as black fur over b white </li></ul>B B b b Bb Bb Bb Bb All black offspring
  25. 27. Autosomal Dominant <ul><li>Huntingtons Disease </li></ul><ul><li>Achondroplasia </li></ul><ul><li>Certain Form of Breast Cancer </li></ul>
  26. 28. <ul><li>Galactosemia, Albinism </li></ul><ul><li>Sickle cell Anemia </li></ul><ul><li>Cystic Fibrosis </li></ul><ul><li>Tay-Sachs </li></ul><ul><li>PKU-phenylketonuria </li></ul>
  27. 29. Autosomal Dominant Patterns
  28. 30. Autosomal Recessive Pattern Gene is unable to express itself unless it is in a homozygous condition .
  29. 32. ? ? C C c c c c Cc CC Cc
  30. 33. <ul><li>Incomplete dominance- </li></ul><ul><li>both genes are expressed as intermediate forms </li></ul>
  31. 34. <ul><ul><ul><ul><ul><li>RR-red, WW-white </li></ul></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>RW-pink </li></ul></ul></ul></ul></ul>R R W W RW RW RW RW
  32. 35. R R R’ R’ RR’ RR’ RR’ RR’ Red crossed with white results in pink flowers
  33. 36. Incomplete dominance <ul><li>Both genes are unable to be expressed ,the heterozygote is intermediate in expression </li></ul>R’ R’ R’ R’ R’ R’ R R R R R R
  34. 37. CODOMINANCE - each gene of the allele is expressed The A,B, O Blood type shows Codominance genotypes iAiA, iBiB, iOiO, iAiB, iAiO ,and iBiO iA iA iB iB iAiB iAiB iAiB iAiB
  35. 38. Blood Groups Type Genotypes
  36. 40. Multiple Alleles <ul><li>In this pattern more than two alleles are possible for a trait. </li></ul><ul><li>Blood Groups or types are an example of this also. </li></ul>
  37. 41. Blood Groups Type Genotypes
  38. 42. What about RH Factor <ul><li>Single dominant gene produces an RH antigen labeled + </li></ul><ul><li>RH negative individuals are homozygous recessive - - </li></ul>
  39. 43. Polygenic <ul><li>More than one pair of genes control the trait </li></ul><ul><li>Genes working together </li></ul><ul><li>Expression is varied </li></ul><ul><li>Race is an example </li></ul><ul><li>Most common form of inheritance </li></ul>
  40. 44. Pleitrophy <ul><li>A gene which affects an organism in many ways </li></ul><ul><li>Multiple phenotypic effects </li></ul><ul><li>Ex. Sickle-cell anemia, albinism </li></ul>
  41. 45. Epistasis <ul><li>A gene at one location alters the phenotypic expression of another gene </li></ul><ul><li>Coat color in some mammals </li></ul>
  42. 46. Polygenic Inheritance <ul><li>Additive effect of two or more genes on phenotypic expression </li></ul><ul><li>Phenotypic expression varies along a continuum </li></ul><ul><li>Skin and eye pigmentation </li></ul>
  43. 47. Multifactorial <ul><li>Influenced by both environment and heredity </li></ul>
  44. 48. Sex or X linked Inheritance- genes that are carried on the X chromosome
  45. 49. Barr Bodies <ul><li>When multiple X chromosomes are present one or more will be inactivated leaving only one </li></ul><ul><li>The inactive X forms a dark staining Barr body </li></ul><ul><li>Random inactivation can result in mosaics </li></ul>
  46. 50. Sex-Linked Disorders <ul><li>Genes carried on the X chromsome </li></ul><ul><li>Males only have one- more likely to have trait </li></ul><ul><li>Females can be carriers </li></ul><ul><li>Most important diseases are recessive </li></ul>
  47. 51. <ul><li>Red-green color blindness, hemophilia </li></ul>
  48. 53. Sex linked Patterns
  49. 54. Sex influenced <ul><li>Genomic imprinting-gene expression is dependent on the sex of the individual in which the gene originated </li></ul>
  50. 55. Prader-Willi - deletion of paternal chromosome 15 Angelman syndrome - if inherited from mother Fragile X syndrome - fragment on X caused by triplet repeats
  51. 56. <ul><li>PPLL X ppll </li></ul><ul><li>F1 all PpLl </li></ul><ul><li>F2 PpLl X PpLl </li></ul><ul><li>From 500 offspring </li></ul><ul><li>281 purple long </li></ul><ul><li>93 purple round </li></ul><ul><li>93 red long </li></ul><ul><li>31 red round </li></ul><ul><li>Should yield a </li></ul><ul><li>9:3:3:1 ratio </li></ul><ul><li>F2 hybrid crosses </li></ul>
  52. 57. Linkage Maps <ul><li>Map units or centimorgans = cross over or recombination frequencies </li></ul>
  53. 58. Based on crossover frequencies or the frequencies that genes are recombined in ways that suggest they are linked together. Measured in linkage units or Morgan Units
  54. 59. C 18% 13% 5% <ul><li>6 % </li></ul>A B D C----7----A----6----B---5--D
  55. 60. *If the ratios deviate from the expected ratio they could indicate that genes are linked. *If genes are linked they are inherited together unless they are separated as a result of crossing over. Resulting in 1:1:1:1 ratios *The frequency that these genes are then separated represents the relative distance they are from each other.
  56. 62. Klinefelter’s Syndrome
  57. 65. Karyotype- a picture or arrangement of metaphase chromosomes. Can be taken from- amniocentesis -chorionic vili biopsy Can be taken from any cells captured in metaphase of mitosis. Chromsomes are stained and photographed and then arranged by pairs according to size and banding patterns.
  58. 70. Chromosome Karyotypes
  59. 71. Mutations- any sudden change in genetic material that can be passed on to the next generation
  60. 95. Albinism recessive disorder lack of pigmentation
  61. 98. Deletion A fragment of a chromosome is missing ex. Cri-du-chat syndrome or deletion of the short arm of the b group chromosome results in a sever form of autism
  62. 101. Translocation- exchange of genetic material from one location on a chromosome to another non-homologous chromosome. Ex. D_G translocation causes a form of Down’s Syndrome
  63. 103. Recombinant DNA <ul><li>Plasmid DNA </li></ul><ul><li>Ligase enzyme Bacterial Cell </li></ul><ul><li>Restriction Enzyme Bacterial cell wall </li></ul><ul><li>Host cell Sticky ends </li></ul><ul><li>Vector </li></ul><ul><li>DNA fragment desired gene to be cloned </li></ul>
  64. 104. Recombinant DNA <ul><li>Plasmid DNA </li></ul><ul><li>Ligase enzyme Bacterial Cell </li></ul><ul><li>Restriction Enzyme Bacterial cell wall </li></ul><ul><li>Host cell Sticky ends </li></ul><ul><li>Vector </li></ul><ul><li>DNA fragment desired gene to be cloned </li></ul>
  65. 106. Recombinant DNA <ul><li>Plasmid DNA </li></ul><ul><li>Ligase enzyme Bacterial Cell </li></ul><ul><li>Restriction Enzyme Bacterial cell wall </li></ul><ul><li>Host cell Sticky ends </li></ul><ul><li>Vector </li></ul><ul><li>DNA fragment desired gene to be cloned </li></ul>
  66. 109. Gene Therapy- insertion of genes to correct defects
  67. 111. Mapping a chromosome Linkage maps- measured in centimorgans a unit derived from analysis of cross-over statistics. Measures the frequerncies of crossing over for genes on the same chromosomes.
  68. 112. T T T T T t t t t t T t
  69. 113. pg102 <ul><li>1. I 2. A, 3. F, 4. E, 5. L, 6.J 7. H, 8. M, 9. C, 10. K </li></ul><ul><li>1.b, 2, d, 3. b, 4. c, 5.b, 6. c, 7.c, 8 c 9. b, 10. d, ( pg 104) 11. b, 12. d, 13. b, 14. d, 15. c, 16. d, 17 a, 18. c </li></ul>
  70. 114. 104 <ul><li>None exonerated </li></ul><ul><li>A or O </li></ul><ul><li>A or O </li></ul><ul><li>AB </li></ul><ul><li>B. or O. </li></ul>
  71. 115. Pg 111 <ul><li>3. b, 4. d, 5. d, 6. b, 7. d, 8. a, 9. a, 10 a, 11. d, 12. b, 13. c, 14. d, 15. a, 16. c, 17. b, 18. c, 19. a </li></ul>