BIMM 120 CH 8

  1. bacterial RNA polymerase holoenzyme is composed of?
    • core polymerase: required for elongation phase
    • sigma factor: required for initiation
  2. sigma factors help detect ____
  3. where are the consensus sequences for sigma-70
    -35 and -10
  4. One way to measure level of gene expression?
    reporter proteins
  5. how do sigma factors recognize specific DNA?
    form fits function
  6. initiation (transcription)
    RNA polymerase holoenzyme binds to the promoter
  7. elongation (transcription)
    RNA chain is extended
  8. termination (transcription)
    RNA pol detaches from the DNA and releases RNA transcript
  9. two types of termination signals
    • rho-dependent: relies on protein rho and strong pause after stop codon
    • rho-independent: GC rich region of RNA that forms hairpin, 4-8 consecutive U residues
  10. two fundamental criteria for antibiotics
    • kill or retard growth of pathogen
    • must not harm the host
  11. Rifamycin B
    selectively binds to bacterial RNA polymerase and inhibits transcription initiation
  12. actinomycin D
    • nonselectively binds to DNA
    • anti-cancer activity
  13. small RNA (sRNA)
    regulates transcription or translation
  14. tmRNA
    frees ribosomes stuck on damaged mRNA
  15. how is mRNA stability measured?
  16. half-life of mRNA
    1-3 minutes
  17. how many possible codons?
    64 (3 are stop codons)
  18. T/F - Each tRNA must be charged with the proper amino acid after it encounters the ribosome.
    False, before
  19. how are tRNAs charged?
    aminoacyl-tRNA synthetase
  20. two subunits of ribosomes
    30S and 50S to form 70S
  21. what makes the peptide bonds that stitch amino acids
  22. Shine-Dalgarno sequence
    RBS that allows for proper reading frame
  23. initiation (translation)
    brings two ribosomal subunits together, placing first amino acid in position
  24. elongation (translation)
    adds amino acids
  25. termination (translation)
    releases completed polypeptide and ribosomal subunits
  26. two antibiotics that affect translation
    streptomycin and tetracycline
  27. what proteins help the folding of proteins?
  28. protein degradation in bacteria
    ATP-dependent proteases
  29. protein degradation in eukaryotes and archaea
  30. how are proteins meant for cell membrane tagged? What are they bound by? What do they undergo?
    • N-terminal signal sequences
    • signal recognition particle (SRP)
    • cotranslational export
  31. pathway for protein export to periplasm
    SecA-dependent general secretion pathway
  32. Type 1 protein secretion
    • cytoplasm directly to extracellular environment
    • efflux ABC transporter
  33. open reading frames (ORF)
    sequence of DNA that encodes a polypeptide
  34. orthologs vs paralogs
    • same function in different organisms
    • duplicated gene in different species with slightly different function
Card Set
BIMM 120 CH 8