Bio Exam part 1

  1. when does capping, splicing, and polyadenylation take place
    • during transcription- capping and splicing
    • after transcription -polyadenylation
  2. what is the purpose of capping
    • serves as a marker to flag it as a mRNA
    • protect from nucleases
    • used for nuclear export
  3. function of capping enzyme
    bind polII when TFIIH PO polII
  4. alternate splicing
    removing multiple introns at one time
  5. size and length of a spliceosome
    • huge, bigger than a ribosome
    • 25 nm
  6. structure of spliceosome
    snRNA and 80 different proteins
  7. how many genes and proteins in the cell
    • 25,000 genes
    • 100,000 proteins
  8. enzyme responsible for polyadenylation
  9. about how many A's are added to the end of transcripts
  10. function of polyadenylation
    adds stability, required for export, when short it signals RNA degradation
  11. link between polyadenylation and transcription termination
    once repetitive CACA is transcribed, the transcript is cleaved and poly a polymerase recognize the repeat sequence and adds the As
  12. error rate of translation
    1/1000 aa
  13. when does translsation take place in the cell cycle
    the whole cycle
  14. components of mRNA
    • 5' methyl guanosine cap
    • 5' UTR - (100-1000)
    • start codon(AUG)-methionine
    • translated sequence
    • stop codon
    • 3'UTR
    • polyadenylation sequence
  15. components of a ribosome
    4 rRNAs and 82 proteins
  16. relationship between nobel prizes and ribosome
    • x-ray crystallography used to solve part of ribosome structure 
    • later nobel prize solved full structure of ribosome
    • another prize used cryoem to solve full picture
  17. APE of ribosome
    • A-where new aatRNA ribosome enters
    • P-where peptide bonds form
    • E-where empty tRNA exists
  18. how many nucleotides in tRNA
    75-95 nucleotides
  19. process of initiation
    • mIF bind directly to 5' cap
    • recruits small ribosome subunit bound to eIF2-tRNAmet
    • scans down transcript for start codon AUG and stops there
    • once there eIF2 no longer inhibits large subunit from binding
    • AUG and CAU base pairing cause GTP hydrolysis of eIF2 turns off
    • large subunit binds
    • eIF2 releases tRNA and transfers to large subunit and goes to P site (empty a and E site)
  20. Process of Elongation
    • if tRNA matches EF1 hydrolyzes its GTP and is released
    • peptide bond forms between P and A site
    • P site aa moves to A site
    • EF2 hydrolyzes its GTP and disinhibits ribosome movement, allowing it to move 3 bp down
  21. termination of translation
    hit stop codon of transcript
  22. protein lipid ratio of membranse
  23. type of protein associated with the membrane
    transmembrane proteins, peripheral proteins that bond to polar head group, and anchored proteins that contain long lipid to anchor in the membrane
  24. proteins that assist in folding
  25. chaperonins
    large hollow tube, hydrophobic interior, ATPases
  26. what type of proteins use chaperonins
    cytoplasmic proteins
  27. structure of heat shock proteins
    • N-terminal domain - like actin ATPs
    • C-terminal domain - clamp hydrophobic 
    • binds to hydrophobic amino acids
  28. types of membrane proteins involving transport
    • channel proteins
    • carrier proteins
    • secondary transporters
  29. channel proteins
    • opens up a hole in the membrane allow molecules to flow down a concentration gradient in to the cell
    • no energy required, rapid transport
  30. carrier proteins
    a specific molecule can move through the membrane across a gradient, requires not ATP, but slower than channel proteins
  31. secondary transporters
    contains pumps:used ATP to pump molecules against a concentration gradient, very specific and slow
  32. translocons
    • transport proteins across membranes, and unfolds proteins
    • can use pump or gradient
  33. function of signal peptides
    • used for receptor binding and protein localization
    • used to bind to escort proteins
Card Set
Bio Exam part 1