biol 330 exam 2 stuff that aids transc/transl

function of RNA poly I

transc rRNAs

function of RNA poly II

transc pre-mRNAs, snoRNAs,

some miRNAs, some snRNAs

function of RNA poly III

transc tRNAs,

small rRNAs, some miRNAs, some snRNAs

Running has Materfully Trimmed Sideburns

RNA poly I - rRNA

RNA poly II - mRNA

RNA poly III - tRNA

RNA poly IV/V (plants) - siRNA

function of IF-1

(step 2)

bind to 30s small subunit (blocks A site so only fMet-tRNA can enter P site)

prevent charged tRNA from binding to A site prematurely

prevent 50s subunit from binding

function of IF-2

(step 3)

bind to initiator fMet-tRNA, transfers it to the P site of 30s-mRNA

GTP hydrolysis used to attach fMet-tRNA to P site, IF leaves, and 50s subunit binds

(creates 70s subunit, places intiator tRNA)

function of IF-3

(step 1)

bind to 30s small subunit, preventing it from rejoining with 50s prematurely

helps 30s subunit bind mRNA and find start codon (with shine dalgarno)

timeline of IFs 1, 2, 3

• IF-3 (separates) binds 30s, blocking 50s, helping 30s bind mRNA

• IF-1 (blocks) binds A site, blocking it so only initiator tRNA can go to P site

• IF-2 (delivers) brings fMet-tRNA, places it on P site of 30S-mRNA complex

  • IF-2 hydrolizes GTP, 50s joins, all IFs leave —> 70s joined

function of EF-Tu

catalyze binding of incoming charged tRNA to A site

req GTP

function of EF-G

catalyze movement (translocation) of peptidyl-tRNA and mRNA A—>P

req GTP

timeline/summary of EFs Tu and G

• EF-Tu (delivery) (binds GTP + charged tRNA)- delivers tRNA to A site, only hydrolizes GTP to let go if the anticodon matches the codon

• EF-G (rib down the mRNA) (binds GTP + charged tRNA)- after peptide bond formation, binds rib. hydrolizes GTP to push ribosome forward by one codon (A—>P, P—>E) (opens A for next charged tRNA)

• Tu = truck - delivers tRNA to A site

• G = goes forward - moves ribosome along mRNA

function of RF1 and RF2

recognize stop codons, catalyze release of polypeptide from tRNA

mimic tRNA to bind to A site, trigger peptidyl transferase to hydrolize bond betw peptide and tRNA in P site

function of RF3

stimulates release of RF1 an RF2

binds rib after peptide release, hydrolizes GTP to dissociate the other RFs from rib