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Operons

  1. what is an operon?
    a cluster of functionally related genes (DNA) that is controlled by a single on-off switch
  2. Is the promoter transcribed?
    no
  3. WHat is the operator?
    segment of DNA that acts as the regulatory "switch"
  4. What does an operon contain?
    • promoter
    • operator
    • structural genes
  5. Transcription of the __ gene is always turned __; it is NOT __.
    • repressor
    • on
    • regulated
  6. All of the structural genes of an operon are transcribed onto a single __ mRNA.
    polycistronic
  7. When the active repressor binds to the operator and blocks RNA polymerase, what happens to transcription?
    it is blocked
  8. This is a form of __ regulation.
    allosteric
  9. What happens if tryptophan is absent?
    repressor inactive and operon on
  10. What happens if tryptophan is present?
    repressor active and operon off
  11. What is the default for the trp operon?
    for transcription to occur
  12. What enzyme gets lactose into the cell?
    galactoside permease
  13. What is the default for the lac operon?
    for transcription to be blocked and not occur
  14. What happens if lactose absent?
    repressor active, operon off
  15. What happens if lactose is present?
    repressor inactive, operon on
  16. an activator of transcription?
    • CAP 
    • catabolite activator protein
  17. If cAMP binds to CAP, what happens?
    CAP is actviated
  18. What does activated CAP do?
    attaches to promoter of lac operon and increases affinity for RNA pol
  19. What kind of control is lactose under?
    negative and positive from CAP
  20. In the lac operon, what is transcription stimulated by?
    presence of lactose and absence of glucose
  21. In tryptophan, what is transcription stimulated by?
    basece of tryptohan
Author
DesLee26
ID
187898
Card Set
Operons
Description
Bio
Updated

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