UMMC MICRO 2 test 2 4th

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UMMC MICRO 2 test 2 4th
2012-10-01 15:01:06
UMMC MICRO test 4th

UMMC MICRO 2 test 2 4th
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  1. What is the difference between Homologous and non-homologous recombination?
    • Homologous recombination results in DNA transfer from one region of DNA to another very similar region, such as from one chromosome to another. It is mediated by RecA enzyme and ssDNA binding protein
    • Non-homologous recombination requires less or no similarity and is mediated by DDE transposases
  2. Define Insertion sequences, Composite transposons, and Replicative transposons
    • IS – consists of transposase and associated repeat sequences
    • Composite Tn – consists of TWO IS elements plus any DNA between them and associated repeat sequences
    • Replicative Tn – consists of transposase, resolvase, other genes, and associated repeat sequences
    • IS and composite Tn are regular jumping genes
    • Replicative Tn makes a copy but keeps the original (resolvase removes DNA tension)
  3. Where is the mobility of the blaZ system in Staph aureus?
    It is carried on Tn552 which can be carried on larger genetic Tns such as Tn6013
  4. What type of secretion system is the sex pilus?
    Type IV
  5. What is the difference between conjugative plasmids and mobilizable plasmids?
    • Conjugative plasmids are self transmissible,
    • Mobilizable plasmids are smaller and lack Mpf, but can transfer if a conjugative plasmid starts the process – they must contain the oriT site
  6. What is the difference between F plasmid conjugation and Hfr conjugation?
    • F plasmid conjugation sends a copy of the self replicating plasmid to join the target cell and thus converts the target cell into an F+ cell
    • Hfr conjugation sends a section of DNA from the chromosome to the target cell that is basically random and does not convert the target cell into a F+ cell