Chapter 6: Translation Flashcards
How many codons go for the each base triplets?
- 3 letter codons
The large ribosomal subunit ensures what?
- that the reading frame is correct
AUG codon is what in eukaryotes?Prokaryotes?
- STARTING CODON …MET in eukaryotes
- FMET in bacteria
UAG codon is the ___ codon??? How many?
- stop codon
-3
L> UAA, UAG , UGA …they al code for a release factor
tRNA specifics:
- Amnioacyl tRNA synthetase??
- attaches the correct aa to tRNA
tRNA specifics:
- Aminoacylation?
- process of attaching the correct aa to tRNA
20 enzymes?
Ribosomal Details:
- three sites what are they?
- A site
- P site
- E site
Ribosomal Details:
- A site??
- P site???
- E site??
- Amnioacyl-tRNA binds here, where tRNA brings in the aa …fresh one
- Peptidyl-tRNA location …where the growing polypeptide chain is! peptide bonds form
- Empty tRNA ..uncharged tRNA. … where tRNA binds on its path from the p site leaving the ribosome.
Ribosomal Details:
- aa’s are let go from the p site and they attach to what site?
- A site….where there originally was only one amino acid….and stays there for a short time
L> translocation occurs and the ribosomal subunit moves…it now has a new A site and a fresh charge tRNA comes in
Initiation of Translation (Prokaryotes):
- AUG of mRNA binds to the _____???
- small ribosomal sub unit
Initiation of Translation (Prokaryotes):
- AUG of mRNA binds to the small ribosomal subunit…..
L> Initiation factors??
- IF1, IF2 and IF3 ( prokaryote IF’s)
Initiation of Translation (Prokaryotes):
- AUG of mRNA binds to the small ribosomal subunit…..
- Shine Delgarno sequence??
- upstream from the start codon close to the 5’ cap…it helps the small Ribosomal subunit bind
Initiation of Translation (Prokaryotes):
- AUG of mRNA binds to the small ribosomal subunit…..
L> Does anything occur to the codons that are upstream from the start codon?
NO
Initiation of Translation (Prokaryotes):
- AUG of mRNA binds to the small ribosomal subunit…..
- The initiator ___ binds to the AUG now??
- tRNA….fMET in bacteria
anticodon ( 5’ CAU 3’
Initiation of Translation (Prokaryotes):
- AUG of mRNA binds to the small ribosomal subunit…..
L> the next step after the initiator tRNA binds is??
- the large ribosomal subunit binds!
Initiation of Translation (Prokaryotes): Initiation Factors....GO IF-1 IF-2 IF-3
- prevents initiator tRNA from binding to the wrong site on the small RSU
- helps the initiator tRNA bind properly
- Prevents the large subunit from binding
L> normally a tRNA with a fresh aa goes to site a but fMET (in bacteria this is where AU is located..) it goes to the P site.
L> this only happens once…every tRNA comes in and goes to A site with a fresh aa this point onward…only fMet foes to Psite.
Elongation of Polypeptide:
- Requires
L> ____ to bind to ribosome
L> ____ formation via peptidyl transferase
L> ____ exactly one codon toward the 3’ end of mRNA.
- Amnioacyl tRNA
- Peptide bond
- Ribosome translocates
Nontranslated region is what?
everything to the left of the start codon!
L> aka upstream
Polyribosome:
- After ribosome translocation occurs what happens?
- a second initiation of translation occurs…
L> 8-1- ribosomes may synthesize proteins from a single mRNA molecule.
L> if there is enough room on the mature RNA
L> this happens in both eukaryotes and pros
What is unique about translation in prokaryotes?
sometimes the 3’ end is still being transcribed while it is being translated….since mRNA is not processed beforehand like it is in eukaryotes.
Termination of Translation?
- A chain terminating ____
- codon
Termination of Translation?
- The cain terminating codon is recognized by ?
- release factors
L> release of polypeptide in P site from tRNA
L> release empty tRNA from ribosome
L> release ribosomal subunits from mRNA
L> once the tRNA is empty it will go to get charged again to be used.
