chapter 14 notes

  1. mutations
    stable, heritable changes in DNA base sequences
  2. allele
    alternatve form of a gene
  3. recombination
    process in which one or more nucleic acids are rearranged or combined to produce a new nucleotide sequence
  4. spontaneous mutations
    occur without exposure to external agents
  5. cause of DNA replication errors
    base tautomerization resulting in transition and transversion mutations
  6. alternative hypothesis for mutation
    somebacteria can select particular mutations to better adapt to the environment
  7. hypermutation
    random generation of multiple mutations, survivors are only those cells with favorable mutations
  8. base analogs
    structurally similar to normal bases that make mistakes when added to polynucleotide chains
  9. DNA modifying agents
    alter a base causing it to mispair
  10. intercalating agents
    distort DNA to induce single nucleotide pair insertions and deletions
  11. what does UV damage do to DNA
    forms thymine dimers so the DNA no longer serves as a template
  12. forward mutation
    going from a wild type to a mutant form
  13. reversion mutation
    mutant phenotype goes to a wild type mutation
  14. suppressor mutation
    occurs when the second mutation is at a different site htan the original mutation
  15. point mutations
    mutations that affect protein structure
  16. silent mutation
    change nucleoside sequence of codon - but not the encoded amino acid
  17. missense mutation
    a single base substitution that changes codon for one amino acid into codon for another amino acid
  18. nonsense mutation
    converts a sense codon to a stop codon
  19. frameshift mutation
    results from insertion or deletion of one or two bases pairs in the coding region of the gene
  20. conditional mutations
    expressed only under certain environmental conditions
  21. auxotrophic mutant
    unable to make an essential macromolecule
  22. regulatory sequence mutation
    mutation in the operator site and produce altered operator sequences not recognized by the repressor
  23. what happens when tRNA or rRNA genes become mutated
     protein synthesis is interrupted
  24. replica plating technique
    used to detect auxotrophic mutants
  25. ames test
    used to test for plate without test mutagen and one with, check for mutation rate
  26. proofreading
    correction of errors in base pairing made during replication
  27. excision repair
    corrects damage that causes distortions in double helix
  28. 2 types of repair systems
    • nucleoside excision repair
    • excision repair
    • bot remove damaged DNA stract using an intact complementary strand as template
  29. photoreactivation
    directly repairs thymine dimers
  30. photolyase
    catalyst that separates thymine dimers
  31. alkyltransferase
    catalyst for direct repair of alkylated bases
  32. mismatch repair system
    mismatch correction enzyme scan newly synthsized dna for mismatched pairs and then they are removed and replaced by DNA polymerase and ligase
  33. DNA methylation
    used by e.coli mistmatch repair system to distinguish old dna strands from new strands (new ones aren't methylated)
  34. recombinational repair
    repairs dna with damage in both strands, uses an undamaged dna molecule
  35. what protein catalyzes recombination events
  36. SOS response
    used to repair excessive damage that halts replications and involves recA protein
  37. recombination
    process in which one ore more nucleic acids are rearranged or combined to produce a new nucleotide sequence
  38. what creates new allele combinations in meiosis
    crossing over
  39. transfer of genes from partents to progeny
    vertical gene transfer
  40. exogenote
    dna that is transferred to recipient
  41. endogenote
    genome of recipient
  42. merozygote
    recipient cell that is temporatily diploid as result of transfer process
  43. three types of recombination:
    • homologous recombination
    • site specific recombination
    • transposition
  44. nonreciprocal homologous recombination
    incorporation of a single strand of DNA into the chromosome forms a stretch of heteroduplex DNA
  45. what uses sit specific recombination
  46. transposable elements
    • segments of DNA that move about the genome in a process called transposition
    • jumping genes
  47. simplest transposable elements are
    insertion sequences
  48. composite transposons
    transposable elements which contain genes other than those used for transposition
  49. bacterial plasmids
    small, autonomously replicating DNA molecules that can exist independently or, integrate reversibly into the host chromosome
  50. episomes
    DNA molecule that can integrate reversibly into the host chormosome
  51. conjugative plasmids
    can transfer copies of themselves to other bacteria during conjugation
  52. what does the transfer of genes between bacteria depend on
    • direct cell to cell contact
    • type 4 secretino system
  53. f+ f- mating
    a copy of the f factor is transferred to the recipient and does not integrate into the host chromosome
  54. results when the f factor incorrectly leaves the host chromosome
    F' conjugation
  55. bacterial transformation
    uptake of naked DNA by a competent cell followed by incorporation of the DNA into the recipient cell's genome
  56. transduction
    the transfer of bacterial genes by viruses
  57. lytic cycle
    viral process in which the host cell is destroyed or the viral DNA can integrate into the host genome, becoming a latent prophage
  58. generalized transduction
    • any part of the bacterial genome can be trasnferred
    • occurs during the lytic cyle
    • host DNA fragments mistakenly packaged into phage head
  59. when can specialized transduction occur
    temperate phages have establised lysogeny
  60. genome mapping
    locating genes on an organism's chromosome
Card Set
chapter 14 notes
chapter 14 notes for microbiology prescott