Chapter 6: Translation Flashcards

1
Q

How many codons go for the each base triplets?

A
  • 3 letter codons
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2
Q

The large ribosomal subunit ensures what?

A
  • that the reading frame is correct
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3
Q

AUG codon is what in eukaryotes?Prokaryotes?

A
  • STARTING CODON …MET in eukaryotes

- FMET in bacteria

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4
Q

UAG codon is the ___ codon??? How many?

A
  • stop codon
    -3
    L> UAA, UAG , UGA …they al code for a release factor
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5
Q

tRNA specifics:

- Amnioacyl tRNA synthetase??

A
  • attaches the correct aa to tRNA
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6
Q

tRNA specifics:

- Aminoacylation?

A
  • process of attaching the correct aa to tRNA

20 enzymes?

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7
Q

Ribosomal Details:

- three sites what are they?

A
  • A site
  • P site
  • E site
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8
Q

Ribosomal Details:

  1. A site??
  2. P site???
  3. E site??
A
  1. Amnioacyl-tRNA binds here, where tRNA brings in the aa …fresh one
  2. Peptidyl-tRNA location …where the growing polypeptide chain is! peptide bonds form
  3. Empty tRNA ..uncharged tRNA. … where tRNA binds on its path from the p site leaving the ribosome.
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9
Q

Ribosomal Details:

- aa’s are let go from the p site and they attach to what site?

A
  • 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
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10
Q

Initiation of Translation (Prokaryotes):

- AUG of mRNA binds to the _____???

A
  • small ribosomal sub unit
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11
Q

Initiation of Translation (Prokaryotes):
- AUG of mRNA binds to the small ribosomal subunit…..
L> Initiation factors??

A
  • IF1, IF2 and IF3 ( prokaryote IF’s)
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12
Q

Initiation of Translation (Prokaryotes):

  • AUG of mRNA binds to the small ribosomal subunit…..
  • Shine Delgarno sequence??
A
  • upstream from the start codon close to the 5’ cap…it helps the small Ribosomal subunit bind
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13
Q

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?

A

NO

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14
Q

Initiation of Translation (Prokaryotes):

  • AUG of mRNA binds to the small ribosomal subunit…..
  • The initiator ___ binds to the AUG now??
A
  • tRNA….fMET in bacteria

anticodon ( 5’ CAU 3’

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15
Q

Initiation of Translation (Prokaryotes):
- AUG of mRNA binds to the small ribosomal subunit…..
L> the next step after the initiator tRNA binds is??

A
  • the large ribosomal subunit binds!
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16
Q
Initiation of Translation (Prokaryotes):
Initiation Factors....GO
IF-1
IF-2 
IF-3
A
  1. prevents initiator tRNA from binding to the wrong site on the small RSU
  2. helps the initiator tRNA bind properly
  3. 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.
17
Q

Elongation of Polypeptide:
- Requires
L> ____ to bind to ribosome
L> ____ formation via peptidyl transferase
L> ____ exactly one codon toward the 3’ end of mRNA.

A
  • Amnioacyl tRNA
  • Peptide bond
  • Ribosome translocates
18
Q

Nontranslated region is what?

A

everything to the left of the start codon!

L> aka upstream

19
Q

Polyribosome:

- After ribosome translocation occurs what happens?

A
  • 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
20
Q

What is unique about translation in prokaryotes?

A

sometimes the 3’ end is still being transcribed while it is being translated….since mRNA is not processed beforehand like it is in eukaryotes.

21
Q

Termination of Translation?

- A chain terminating ____

A
  • codon
22
Q

Termination of Translation?

- The cain terminating codon is recognized by ?

A
  • 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.