Biochem 501: Part IV.7: Gene Regulation

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  1. What metabolizes Lactose?
  2. Allolactose signals what?
    lacZ and beta-galatosidase expression
  3. Cause for temporary pause in growth in bacteria when media is shifted?
    • Glucose is in initial plate, so bacteria uses glucose, does not express lactose genes because it is unnessecary
    • Switched to lactose plate, need to be able to process lactose
    • Allolactose promotes lacZ and results in in expression in form of beta-galactosidase
  4. What controls enzymes levels
    Molecular regulation of gene expression
  5. Induction versus Repression
    • Induction is turning on gene in presence of a molecular signal
    • Repression is turning off a gene in presence of a molecular signal
  6. Promoters integrate what kinds of signals.
    + and -
  7. Repressor proteins stop gene expression by:
    binding the promoter and preventing the RNAP from binding (steric competition)
  8. Allagalactose promotes expression by:
    Binding to the repressor protein and preventing it from binding promoter
  9. How does glucose decrease result in beta-galactosidase expression
    • As glucose decreses cAMP increase
    • cAMP binds CAP (CRP cAMP Receptor Protein)
    • cAMP+CAMP interact with RNAP to stimulate gene expression
  10. Negative Regulation
    • Repressor bound to promoter inhibits transcription
    • Ligand binds to and removes repressor
    • Likewise, a ligand bind may result in the repressor binding to promoter and turning it off
  11. Positive Regulation
    • Bound activator protein promotes transcription
    • Ligand binds removes activator and prevents gene transcription
    • Similarly, ligand binding may result in activator binding promoter and turning it on
  12. Lac operon is a ___ system
  13. Regulators can be close or far from the gene
  14. DNA looping
    proteins bound distally cooperate with proteins found closer
  15. Basic principles of expression are __, but molecularly ___
    conserved, diverse
  16. Transcriptonal regulators directly influence:
    initiation complex assembly and stability.
  17. Transcription domains essential for
    promoting transcription
  18. Means of regulation for gene expression
    • Constitutive expression: some genes are mostly always on at same level
    • Developmental gene regulation: some genes undergo long-lasting changes in expression in response to intracellular and/or extracellular signals
    • Cell cycle gene regulation: some genes turned on at specific steps of cell cycle.
  19. How do proteins recognize specific DNA sequence
    • Amino acid side chains contact functional groups in nucleotide bases (polypeptide motifs)
    • Proteins form H-bonds with nucleotide bases
    • Most bind in the major, not minor groove
Card Set
Biochem 501: Part IV.7: Gene Regulation
Biochem 501 FINAL
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