Translation L5

Question 1

what RNAs does translation need

Answer 1

rRNA = ribosomes
tRNA = amino acid (amino acyl tRNA)
mRNA = template strand

Question 2

what is the prokaryote ribosome structure

Answer 2

70S
30S = 16SrRNA
50S = 23S rRNA and 5SrRNA

Question 3

What is a eukaryote ribosome made of

Answer 3

80S

40S and 60S

Question 4

What is needed for prokaryote initiation for protein synthesis

Answer 4

30S, 50S ribosome subunits
mRNA
amino-acyl tRNA formyl-methionine (AUG codon)
Initiation factors 1,2,3
GTP

Question 5

What is ribosome dissociation

Answer 5

Spontaneous

IF1 and IF3 bind to 30S unit, stop re-association

Question 6

What are the stages of prokaryote initiation

Answer 6

1. Ribosome dissociation - IF1 and IF3 bind to 30S subunit to prevent re-association with 50S
2. IF2 and GTP complex with formyl methionine tRNA
3. tRNA brought to mRNA, complementary to AUG codon on mRNA
4. Form 30S initiation complex
5. IF3 lost
6. GTP hydrolysed to GDP (+Pi) produces energy
7. Energy displaces IF1 and IF2 so 50S subunit can re-associate with 30S

Question 7

What is the A binding site on ribosome

Answer 7

Amino-acyl

Question 8

What is the P binding site on the ribosome

Answer 8

Peptidyl

Question 9

How does elongation occur in prokaryotes

Answer 9

Elongation factor(EF-Tu) binds with GTP to the next complementary tRNA in mRNA sequence
The tRNA brought to the A site, binds - releases EF-Tu and GTP
Peptide bond forms between the amino acids in the P (FMet) and A sites
Is cataylsed by peptidyl transferase
GTP hydrolysed releases energy so ribosome shifts three nucleotides to right till reach termination

Question 10

What tRNA is present in the P site at the start

Answer 10

FMet