Question 1
According to the hybrid state model, if we consider the hybrid state of a tRNA such that its base is bound to the P site of 30S subunit, where will its head be bound?
A. A site of 50S
B. P site of 50S
C. E site of 50S
D. Unbound
View Answer
Answer: Option C
Explanation:
According to hybrid model 1st the head part shifts to the next site in the cycle then the foot part of tRNA bound to 30S subunit shifts along with the input of energy. Thus, according to our question the head should be at E site.
Question 2
After the Ef-G cycle the A site_________
A. Houses peptide bound tRNA
B. Amino acid bound tRNA
C. Empty
D. Uncharged trNA
View Answer
Answer: Option C
Explanation:
The EF-G factor helps in translocation of the ribosome such that the peptide bound tRNA shifts to the P site and A site becomes empty and available to bind another charged tRNA.
Question 3
Binding of RF3.GTP to the ribosome helps in release of the ____________
A. Peptide
B. Release factor 1
C. tRNA
D. Ribosome
View Answer
Answer: Option B
Explanation:
RF3.GTP binds the ribosome after the peptide is already released by the RF1. It hydrolyses to release the RF1 instead.
Question 4
EF-Tu GTP complex is ____________
A. Very unstable
B. Unstable
C. Stable
D. Very stable
View Answer
Answer: Option D
Explanation:
The GTP bound form of EF-Tu is so stable that it needs another factor EF-Ts to break it down and reattach it to another GTP.
Question 5
How many factors play a role in termination of translation?
A. 1
B. 3
C. 5
D. 7
View Answer
Answer: Option C
Explanation:
The factors are- RF1-3, RRF and Ef-G respectively. The EF-G factor finally hydrolyses the GTP that leads to final translocation step freeing the ribosome.
Question 6
If a peptide is 160 amino acids long, How many GTP and ATP molecules does it use for elongation?
A. 318 GTP + 160 ATP
B. 478 GTP + 160 ATP
C. 320 GTP+ 320 ATP
D. 478 GTP+ 320 ATP
View Answer
Answer: Option A
Explanation:
There are 159 translation steps from initiation to termination. Each step has an input of 2 GTP in form of EF-Tu and Ef-G. For all 160 amino acids we have to charge it with 160 ATP.
Question 7
What is the rate of translation in prokaryotes under adequate conditions?
A. 10 amino acid per second
B. 20 amino acid per second
C. 30 amino acid per second
D. 40 amino acid per second
View Answer
Answer: Option B
Explanation:
While the ribosome can read about 50-60 nucleotides per second, due to triplet codon the maximum number of amino acids added per second would be : (60/3) = 20 amino acid per second.
Question 8
Which factor or factors lead to the ultimate disassembly of the ribosomal complex?
A. RF1 and RF3
B. RF3 and RRF
C. RRF and EF-G
D. RF2 and EF-G
View Answer
Answer: Option C
Explanation:
The RRF first replaces the RF3 from the termination complex. Then, EF-G translocates the complex for the last time freeing the mRNA, Ribosome, tRNA and the factors.
Question 9
Which factors lead to disassociation of the ribosomal subunits?
A. RRF and Ef-G
B. IF1 and IF2
C. Rf1 and RRF
D. IF-1 and IF-3
View Answer
Answer: Option D
Explanation:
While the release factor releases the ribosome from the termination complex, in order to keep the ribosome functional the 50S and 30S subunits should be separated. This is maintained by IF1 and IF3 (mainly by IF3) which prevents re-association.
Question 10
Which of the elongation factor binds to amino acyl tRNA?
A. Ef-Tu
B. Ef-Ts
C. Ef-G
D. GDP
View Answer
Answer: Option A
Explanation:
EF-Tu in GTP bound form binds to amino acyl tRNA. It helps to bring the amino acid to the ribosome, and one placed in proper position the GTP hydrolyses.
Question 11
Which of these factors can recognize the UAA stop codon?
A. RF1
B. RF3
C. RRF
D. Ef-G
View Answer
Answer: Option A
Explanation:
RF1 (as well as RF2) can recognize the stop codons at the A site. They can recognize the UAA and UAG stop codons on the mRNA.