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Test 2 Thursday Nov. 17

Test 2 Thursday Nov. 17. Quiz 4 answers http://webct.mun.ca:8900/ All quizzes on WebCT for Review Office Hours: Tuesday 10:30 – 12:00 Wed. 1:15 – 2:15 or by appointment: 737-4754, dinnes@mun.ca. Mendelian Genetics. . . . Topics:

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Test 2 Thursday Nov. 17

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  1. Test 2 Thursday Nov. 17 Quiz 4 answers http://webct.mun.ca:8900/ All quizzes on WebCT for Review Office Hours: Tuesday 10:30 – 12:00 Wed. 1:15 – 2:15 or by appointment: 737-4754, dinnes@mun.ca

  2. Mendelian Genetics    Topics: -Transmission of DNA during cell division Mitosis and Meiosis - Segregation - Sex linkage (problem: how to get a white-eyed female) - Inheritance and probability - Independent Assortment - Mendelian genetics in humans - Linkage - Gene mapping    • Gene mapping in other organisms • (fungi, bacteria) • - Extensions to Mendelian Genetics • - Gene mutation • - Chromosome mutation • (- Quantitative and population genetics) • B2900     

  3. Mutation Source of genetic variation: Gene Mutation - somatic, germinal Chromosome mutations (Ch. 11) - structure (deletion, duplication, inversion, translocation) - number  

  4. Chromosome Mutation(2. changes in number) Euploidy: variation in complete sets of chromosomes Aneuploidy: variation in parts of chromosome sets

  5. Euploidy 1x monoploid (1 set) = n 2x diploid (2 sets) = 2n 3x triploid 4x tetraploid 5x pentaploid polyploid (> 2 sets) 6x hexaploid n = # chromosomes in the gametes 2n 4n

  6. Polyploids Autopolyploids: within one species Allopolyploids: from different, closely related species

  7. Polyploids Largerthan Diploids

  8. Polyploids Triploids: = 3n - problems with pairing during meiosis - unbalanced gametes - usually sterile Applications: seedless fruits, sterile fish aquaculture

  9. Formation of Triploids n = 3n n n Polar bodies = 3n n 2n n n

  10. Triploids (3x) Why can’t a triploid produce viable gametes ?

  11. Fig. 11-5

  12. Triploids (3x) Gametes x = 1

  13. Gametes Triploids viable or x = 2 Non- viable

  14. Viable Gametes from Triploids # of chrs 2 3 x - 1 1 Probability (2x or x gamete) = ( ) if x = 10 Prob. = 0.002 of viable gametes 4 2

  15. Triploid Fish Frankenfish-Biotech 3n carp

  16. Autotetraploid

  17. Autotetraploid Doubling of chromosomes: 2x----> 4x Even number of chromosomes: normal meiosis 2<---->2 segregation------> functional gametes

  18. Polyploids Autopolyploids: within one species Allopolyploids: from different, closely related species Hybridization

  19. Allopolyploid 2n = 14, n = x = 7 Origin of WheatFig. 11-10 hybrid 2n = 28 n = 14 Chromosome sets: A, B, D 7 7 7 7 14 Triploid 2n = 42 x = 7 n = 21

  20. Polyploidy Plants: speciation (wheat) Animals: - rare (sex determination) - fish (salmon: tetraploid) - parthenogenetic animals 123 11 22 12 12

  21. Plant Polyploids

  22. Chromosome Mutation(changes in number)  Euploidy: variation in complete sets of chromosomes Aneuploidy: variation in parts of chromosome sets

  23. normal Aneuploidy Nullisomics (2n - 2) Monosomics (2n - 1) Trisomics (2n + 1)

  24. Aneuploidy Nullisomics (2n - 2) - lethal in diploids - tolerated in polyploids Monosomics (2n - 1) - disturbs chromosome balance - recessive lethals hemizygous Trisomics (2n + 1) - sex chromosomes vs autosomes - size of chromosome

  25. Aneuploidy Non-disjunction: Gametes Meiosis I n + 1 n - 1 Meiosis II n + 1 n - 1 n n x n - 1 ---------> 2n - 1 monosomic n x n + 1 ---------> 2n + 1 trisomic

  26. Human Aneuploids 13 18 21 X Y

  27. Aneuploidy Humans: (live births) Monosomics - XO Turner syndrome - no known autosomes Trisomics XXY Klinefelter sterile male XYY fertile male( X or Y gametes) XXX sometimes normal 21 Down 18 Edwards syndromes 13 Patau

  28. Downs Births per 1000 2 %

  29. 0.62 % 50 %

  30. Mutations Causing Death and Disease in Humans % of live births Gene mutations: 1.2 Chromosome mutations:0.61

  31. Chromosome Mutations(Humans) % of spontaneous abortions Trisomics 26 % XO 9 % Triploids 9 % Tetraploids 3 % Others 3 % Chromosome 50 % abnormalities

  32. Chromosome Mutations Comparison of euploidy with aneuploidy Aneuploids more abnormal than euploids: likely due to gene imbalance Plants more tolerant than animals to aneuploidy and polyploidy (animal sex determination)

  33. Summary genetic analysis Mutation - gene - chromosome (structure, number) Detecting - cytology - phenotype Rate of mutation - low Mutation - source of genetic variation - evolutionary change

  34. Chapter References Mitosis and Meiosis Ch. 4 p. 100 – 112     Prob: 10, 11, 12, 18, 19 Mendelian Inheritance Ch. 5 p. 118 – 129     Prob: 1 – 3, 5, 6, 7, 8, 9 Recombination, linkage maps Ch. 6 p. 148 – 165 Prob: 1-5, 7, 8, 10, 11, 14 Extensions to Mendelian Genetics Ch. 14 p. 459 – 473 Prob: 2, 3, 4, 5, 6, 7 Chromosome Mutations Ch. 11 p. 350 – 377 Prob: 1, 2

  35. Mendelian Genetics    Topics: -Transmission of DNA during cell division Mitosis and Meiosis - Segregation - Sex linkage - Inheritance and probability - Independent Assortment - Mendelian genetics in humans - Linkage - Gene mapping    • Gene mapping in other organisms • (fungi, bacteria) • - Extensions to Mendelian Genetics • - Gene mutation • - Chromosome mutation      

  36. Genetics Part I Part II Molecular Mendelian

  37. Chromosome Theory of Inheritance - genes organized into chromosomes - correlation: Genetics & Cytology - theory can explain segregation and independent assortment

  38. Two types of nuclear division 1. Mitosis (somatic tissue) 2. Meiosis (germ tissue)

  39. Mendelian Genetics Meiosis and mitosis Segregation and independent assortment Sex linkage, sex determination Pedigrees Linkage, recombination and linkage maps

  40. Mendelian Genetics Gene linkage: 3 point test cross, tetrad analysis Extensions (dominance, multiple alleles, pleiotropy, epistasis, penetrance and expressivity) Mutation: gene mutation chromosome mutation (number structure)

  41. Mendelian Genetics Applications Genetic markers as tools: - human diseases - population genetics - genetic structure (gene flow) - systematics and phylogeny - forensics

  42. Mendelian Genetics in Humans Determining mode of inheritance Problems: 1. long generation time 2. can not control matings Alternative: * information from matings that have already occurred “Pedigree”

  43. Human Pedigrees Pedigree analysis: trace inheritance of disease or condition provide clues for mode of inheritance however, some pedigrees ambiguous

  44. Human Pedigrees Pedigree analysis: dominant vs recessive autosomal vs sex linked

  45. Linkage: Human Genetic Diseases Linkage: organization of genes and genome marker genes linked to: Disease genes

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