Cell bio 406 Lecture 4

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Cell bio 406 Lecture 4
2013-08-02 17:57:21
cellular biology

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  1. What is translation?
    process by which proteins are synthesized
  2. Where does translation occur?
    Ribosome in the cytoplasm of eukaryotes.
  3. When is transcription coupled with translation?
    In prokaryotes.
  4. How many steps does translation occur in?
  5. What is initiation?
    Translation machinery recognizes and binds to mRNA.
  6. What is elongation?
    Translation machinery add amino acids to the growing polypeptide chain.
  7. What is termination?
    Translation machinery stops synthesis and dissociates from mRNA.
  8. What are ribosomes?
    A ribosome binds mRNA and tRNA.

    It is the structure where translation occurs.
  9. What makes up a ribosome?
    ribonucleoprotein (rRNA and protein)
  10. What does anti-shine del garno sequence recognize?
    ribosomal binding site (RBS) on mRNA for initiation.
  11. What do eukaryotes have instead of shine del garno sequence?
    5' cap for ribosomal recognition.
  12. What links together amino acids during elongation?
    peptidyl transferase activity
  13. What carries the amino acids?
    acceptor stem
  14. What determines amino acid selection?
    anticodon loop
  15. what is aminoacylation?
    process by which aminoacyl tRNA synthetases add amino acids to the acceptor stem of tRNA.
  16. Where does aminoacyl tRNA syntheses add corresponding amino acid?
    3' end of the tRNA
  17. what does aminoacyl tRNA synthetase recognize?
    anitcodon loop
  18. how many amino acids per enzyme?
  19. How are unnatural amino acids incorporated?
    mutations in enzymes.
  20. what are the different areas in tRNA?
    D-loop, anticodon loop, variable loop, tWc loop, acceptor stem.
  21. What ends initiation?
    synthesis of the first peptide bond of the polypeptide
  22. Where does ribosomal assembly occur?
    in the 5' UTR
  23. What dictates the length of protein?
    start and stop codons
  24. Where is the transcription start?
    between the 5' cap and the 5' UTR.
  25. Where is the start codon?
    Between the 5' UTR and the coding region.
  26. Where is the stop codon?
    Between the coding region and the 3' UTR.
  27. Where is the poly (A) signal?
    Between the 3'UTR and the poly (A) tail.
  28. What subunit binds to mRNA in bacteria?
    30S (16s anti-shine delgarno sequence)
  29. What is required for 30S to bind to mRNA?
    Initiation factors 1 and 3.
  30. What do all initation regions have?
    two consensus elements.
  31. What are the two consensus sequences in bacteria?
    shine-delgarno sequence and AUG.
  32. what is the ribosomal binding site for prokaryotes?
    shine-delgarno sequence
  33. What is the ribosomal binding site in eukaryotes?
    5' cap
  34. Where does the subunit bind to initiate translation in eukaryotes?
    methylated cap
  35. Where does subunit migrate after binding to methylated cap?
    initiation site
  36. what is upstream of the initiation site in eukaryotes?
    Kozak consensus sequence.
  37. What brings the first tRNA to the first codon AUG in prokaryotes?
    IF2, initiation factor 2.
  38. Where does IF 2 bring tRNA in prokaryotes?
    to P site.
  39. When can 50s subunit bind?
    After IFs are released.
  40. What drive elongation?
    Translocation of tRNAs along the different sites of a ribosome.
  41. Where is 1st tRNA placed?
    P site
  42. Where does 2nd tRNA enter?
    A site
  43. Where does tRNA without an amino acid move to?
    E site
  44. Where does the amino acid go when the tRNA moves to the E site?
    to the Amino Acid chain
  45. What loads Aminoacyl-tRNA into the A site?
    Elongation Factor Tu
  46. What is required for translocation?
  47. What kind of tRNA is in the P site?
  48. What type of tRNA enters A site?
  49. What kind of tRNA moves to E site?
    deacylated tRNA
  50. What causes the shift from tRNA binding to translocation?
    alternating binding of EF-Tu and EF-G
  51. How does alternating binding of EF-Tu and EF-G cause shift from binding to translocation?
    Changing the ribosomal structure
  52. What does peptidyl transferase activity do?
    transfers amino acid from tRNA to the polypeptide chain forming peptide bonds.
  53. How many stop codons?
  54. What are the stop codons?
    • UAA ochre
    • UAG amber
    • UGA Opal
  55. What recognizes termination codons?
    protein release factors
  56. What is RF1
    bacterial release factor that recognizes UAA and UAG signals to terminate polypeptide translation
  57. What is RF2?
    bacterial release factor that recognizes UAA and UGA to terminate translation.
  58. What is RF3?
    Removes RF1 and RF2 terminating transcription.
  59. What is RF3 related to?
  60. Who shares genetic code?
    smallest bacteria to complex animals
  61. Can genes be transplanted?
    yes and become transcribed and translated
  62. What regulates translation in mammalian cells?
    mTOR pathway
  63. What does mTOR-Raptor-GbetaL complex block
    Inhibitory effects of 4E-BP1 and S6 kinase
  64. What does mTOR complex with?
    GbL and Raptor
  65. What does 4E-BP1 do?
    binds with  elF4E and blocks its assembly with the 7MeG cap
  66. What does S6K do?
    phosphorylates ribosomal protein S6 to inhibit 43S ribosomal preinitiation complex.
  67. Where is mRNA translated?
    in specific regions of the cell
  68. How do mRNA deliver proteins to their site of synthesis?
    ZBPs zipcode binding proteins
  69. What transports the mRNA to their destination?
    motor proteins along the cytoskeletal systems
  70. What leads to cell polarity?
    protein asymetric localization
  71. why is asymetric localization important?
    It is used to form lamellopodia in migratory cells.
  72. Where do ZBP bind?
    in the 3' UTR
  73. what is mRNP
    messenger ribonucleoprotein
  74. What does mRNP do?
    Controls mRNA localization, translation, and turnover