Genetics Exam 4

  1. Formula for LOD Score
  2. LOD score cutoff to establish linkage linkage, and exclusion
    >3 for linkage, <-2 for exclusion
  3. what are LOD scores?
    measure of linkage between genetic markers and disease causing allele
  4. polygenic inheritance
    traits that are controlled by many more than one gene
  5. chart?chf=bg,s,00000000&cht=tx&chl=V_T%20%3D%20%3F&chs=106x36

    total phenotypic variance = genetic varaince + environmental variance
  6. broad sense heritability
    the total proportion of variance that is due to genetic differences

  7. narrow sense heritability
    the proportion of trait variance that is due to additive genetic differences


    this is measured in parent, offspring regressions
  8. MZ twins

  9. DZ twins


    1/2 of genetic differences among the parents are not shared between full sibs
  10. chart?chf=bg,s,00000000&cht=tx&chl=S%3Du_S-u&chs=162x40

    What are the different terms?
    • S = intensity of selection
    • u_S = mean of sample
    • u = mean of first generation
  11. chart?chf=bg,s,00000000&cht=tx&chl=R%3Du'-u&chs=158x30

    What are the terms?
    • R = response to selection
    • u' = mean of second generation
    • u = mean of first generation
  12. chart?chf=bg,s,00000000&cht=tx&chl=R%3Dh%5E2S&chs=130x36

    what are the terms? What is this equation called?
    Breeder's equation

    narrow sense heritability can help predict the effects of artificial selection

    • R = response to selection
    • h2 = narrow sense heritability
    • S = intensity of selection
  13. more genetic variation = more or less heritability?
  14. What percentage of chromatin is DNA and protein?
    ~50% DNA, ~50% protein
  15. What percent of chromatin proteins are histones?
    50% of the proteins (25% of chromatin)
  16. How many types of histone proteins are there?
    Four major types that form two types of dimers (H2A/H2B, H3/H4). Then two of each dimer form an octamer.

    There is also a fifth major type of histone H1
  17. What is it called when DNA wraps twice around a histone core?
  18. What does the H1 histone do?
    Acts like a "linker", binds outside the nucleosome to stabilize a larger structure
  19. Name the 5 levels of compaction of chromatin
    • histone
    • nucleosome
    • beads on a string
    • solenoid
    • MARs
  20. What is MARs?
    Matrix Attachment Regions - higher-order compaction using protein scaffold

    active transcription in loops between MARs, attached MARs are different in different cell types
  21. polyploidy
    all the chromosomes have "extra" (more than two) copies
  22. triploids tend to be...
    sterile. having 3 pairs disrupts meiotic pairing and reductional division
  23. aneuploidy
    having an extra or missing copy of a single chromosome
  24. protein-coding exons comprise what % of our genome?
    1.5 %
  25. introns comprise what % of our genome?
  26. transposable elements comprise what % of our genome?
  27. regulatory sequences comprise what % of our genome?
  28. unique noncoding DNA comprise what percent of our genome?
  29. repetitive DNA not related to TE's comprise what percent of our genome?
  30. what does colchicine do to plants?
    induces polyploidy in plant cells during cellular division by inhibiting chromosome segregation during meiosis
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Genetics Exam 4
Genetics exam 4