Microbiology 3-8

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Microbiology 3-8
2013-11-18 22:57:33

Study guide 3-8
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  1. Explain what transposable means:
    DNA with the ability to be moved and integrated into different sites in the chromosomes.
  2. Characterize the following types of transposable elements: Insertion sequences
    • "IS" elementsm a short sequence, that only contains the gene for the enzyme transposase and is bounded at both ends by inverted repeats.
    • Transposase is required for transposition and recognizes the IS ends.
  3. Characterize the following types of transposable elements: Composite transposons
    Transposable elements that also contain genes in addition to those needed for transposition.
  4. Characterize the following types of transposable elements: Replicative transposons
    When the O.G. transposon remains at the parental site on the chromosome and a replicate is inserted at the target DNA site.
  5. Identify the characteristics of plasmids:
    • Small & double stranded
    • Can exist independently of chromosomes
    • Contains its own oriC
    • Autonomously replicate and are inherited
  6. Characterize the following type of plasmid:Episome
    can integrate reversibly with the host chromosome
  7. Characterize the following type of plasmid:Conjugative plasmid
    transfer copies of themselves to other bacteria during conjugation
  8. Characterize the following type of plasmid:F factor
    A specific type of conjugative plasmid. It bears genes for cell attachment and plasmid transfer
  9. Identify what is required for conjugation to occur:
    • Direct cell to cell contact mediated by F-pilus
    • Type IV secretion system
    • Rolling circle replication of plasmid
  10. Characterize the following types of cells:F+,F-,HFR, and F'
    • F+ has an F factor
    • F- lacks an F factor
    • HFR has F factor integrated into the bacterial chromosome
    • F' has F factor + cell gene(s)
  11. Describe the results of the following matings: F+ x F-
    Cellular genes are transferred to second host by cell conjugation. A plasmid from F+ moves through sex pilus into F-. The F factor is transferred between the cells, F- becomes F+.
  12. Describe the results of the following matings: Hfr x F-
    Hfr makes a sex pilus, then has a break where the Ffactor is, a piece of DNA breaks off with it and goes into recipient cell. It transfers part of the chromosome and part of the F factor. F- remains F-.
  13. Describe the results of the following matings: F' x F-
    F' has an Ffactor that comes out of the chromosome with chromosome attached. All of it goes to the recipient and turns the F- into F', it gives the Ffactor and genetic information
  14. Conjugation in Gram + bacteria
    • Cell to cell contact through sex pilus.
    • Fewer transfer genes are required.
  15. Explain what transformation is:
    • Uptake of naked DNA by a competent cell.
    • DNA is incorporated into the recipient cell's genome.
  16. Describe the mechanism of transformation in S. pneumoniae:
    • DNA fragment binds to a cell surface receptor.
    • Extracellular endonuclease cuts the DNA into smaller fragments.
    • One strand is degraded, another enters.
    • DNA strand aligns itself with a homologous region on chromosome.
    • DNA strand is incorporated (YAY).
    • Makes the thingey lac+.
  17. Characterize transformation in Gram - cells:
    does not produce protein factor to stimulate competence. takes up DNA only from closely related species. Double strand DNA taken in by vesicles.
  18. Discuss the requirements for transformation:
    • DNA must be in the surrounding environment.
    • DNA must encounter a competent cell.
    • Bacteria have to be in a certain stage of growth.
  19. Explain what transduction is:
    horizontal gene transfer mediated by viruses
  20. Distinguish between generalized transduction and specialized transduction:
    • Generalized:Mispackaging of DNA. LYTIC CYCLE, some viruses only get cellular DNA and inject it into another bacteria
    • Specialized:LYSOGENIC CYCLE, viruses get part prophage part cellular DNA. This is transfered into future cells.