2017 Biochemistry - Protein Synthesis Flashcards

1
Q

Importance of the 3’ end of tRNA?

A

Amino Acid binding site

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Importance of the TYC loop of tRNA?

A

Where tRNA binds to Ribosome

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Importance of the D loop of tRNA?

A

Contains high amounts of dihydrouridine residues (this is recognized by the enzyme tRNA synthetase)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Importance of the ANTICODON loop of tRNA?

A

Contains the Anticodon which is complementary to the codon of the messenger RNA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

How does tRNA and mRNA bind? Parallel or Antiparallel?

A

Antiparallel:
tRNA runs: 3’-5’
mRNA read: 5’-3’

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

How does initiation w/ tRNA and the Ribosome work?

A
  1. Initiation factors dissociate the 70S (80S in eukaryotes) into the parts of 50S & 30S (40S & 60S)
  2. tRNA-Met and mRNA bind the 40S subunit with the help of eIF2. tRNA-fMet (formyl methionine) is the initiation codon for prokaryotes.
  3. The big subunit (60S or 50S) reassemble with the smaller unit and the tRNA-Met introduces the first AA (methionine) into a protein. It binds to the initiation Codon (AUG).
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What are the 4 Initiation factors for eukaryotes and what do they do?

A

eIF-1A & eIF-3: bind 40S
eIF-4F: mRNA complex binds to ribosome subunit
eIF-2: (GTP) binds to tRNA-met which binds AUG
eIF-2: lost as GTP is hydrolyzed and 80S unit formed

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Function of A, P, E sites of Ribosome?

A

A - Acceptor: accepts incoming tRNA
P - Peptide: site where peptide bond is formed for new tRNA as protein is being constructed.
E - Exit

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is required for new peptide bond formation?

A

Elongation Factor 1A (eEF1A) and 1-GTP

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is required for Translocation?

A

This is the movement of the ribosome one-codon down the mRNA.
Requires:
-eEF2 & GTP

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is required for Termination?

A

Stop codon is reached at the A-site

Releasing factors: eRF1 and eRF3

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What are the energy requirements for A.A. tRNA activation and for Elongation/Termination?

A

2 ATP
2 GTP

4 Total high energy bonds

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is the importance of signal peptides?

A

Only in Eukaryotic cells, helps direct Ribosomes to go from cytoplasm to ER, shuttling the protein into the ER for further processing.
Signal Recognition Particle (SRP) - binds to peptide as it is expelled from Ribosome and prevents translation until ribosome docks with ER.
GTP dependent process - Ribosome binding
ATP depended - transport protein through the Ribosome membrane.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Name 2 Eukaryotic Protein Synthesis Inhibitors and what they inhibit (specifically)?

A

Cycloheximide - inhibit peptide bond formation

Diphtheria toxin - catalyze reaction of NAD+ w/ elongation factor, results in inhibition of translocation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Name 2 Eukaryotic & Prokaryotic Protein Synthesis Inhibitors and what they inhibit (specifically)?

A

Chloramphenicol - inhibit peptide bond formation & mitochondrial protein synthesis at high levels
Puromycin - causes premature termination

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Name 3 Prokaryotic Protein Synthesis Inhibitors and what they inhibit (specifically)?

A

Tetracycline - inhibits elongation
Streptomycin - blocks translation
Erythromycin - inhibits translocation