Questions and answers for exam Preparation

MCQs

Total Questions : 282 | Page 20 of 29 pages

Question 191. Which of the following statements regarding the regulation of trp operon expression by attenuation is correct?

Rapid translation of the leader peptide prevents completion of mRNA transcript
Rapid translation of the leader peptide allows completion of mRNA transcript
The leader peptide sequence encodes enzymes required for tryptophan synthesis
The leader peptide sequence contains no tryptophan residues

Discuss Question

Answer: Option A. -> Rapid translation of the leader peptide prevents completion of mRNA transcript
Answer: (a).Rapid translation of the leader peptide prevents completion of mRNA transcript

Question 192. Which of the following about mRNA stability is not correct?

Regulation of mRNA stability is a way of regulating gene expression
Prokaryotic mRNAs have a half-life of only a few minutes
Histone mRNAs have especially long poly-A tails and are stable
It is thought that poly-A tails stabilize eukaryotic mRNAs

Discuss Question

Answer: Option C. -> Histone mRNAs have especially long poly-A tails and are stable
Answer: (c).Histone mRNAs have especially long poly-A tails and are stable

Question 193. Which of the following increases gene expression as much as 200-fold?

TATA box
Insulator
Enhancer
CAAT box

Discuss Question

Answer: Option C. -> Enhancer
Answer: (c).Enhancer

Question 194. The mechanism by which CBP activates transcription is

CBP has DNA methyl transferase activity
CBP has histone acetyl transferase activity
CBP interacts with the basal transcription complex
CBP interacts with the basal transcription complex and has histone acetyl transferase activity

Discuss Question

Answer: Option C. -> CBP interacts with the basal transcription complex
Answer: (c).CBP interacts with the basal transcription complex

Question 195. RNAi stands for

RNA inducer
RNA interference
RNA intron
RNA insertion

Discuss Question

Answer: Option B. -> RNA interference
Answer: (b).RNA interference

Question 196. Which of the following takes place when tryptophan levels are low?

Ribosomes quickly translates sequence 1
Sequence 2 is blocked before sequence 3 is transcribed
Ribosomes pauses at the Try codons in sequence 1
Attenuation at the attenuator structure formed by sequences of 3 and 4

Discuss Question

Answer: Option C. -> Ribosomes pauses at the Try codons in sequence 1
Answer: (c).Ribosomes pauses at the Try codons in sequence 1

Question 197. When DNA segment is in one orientation

The gene for FljB and gene encoding FljA are expressed
The gene for FliC are expressed
The gene for FljB and gene encoding FljA are not expressed
The gene for FljB and gene encoding FljC are not expressed

Discuss Question

Answer: Option A. -> The gene for FljB and gene encoding FljA are expressed
Answer: (a).The gene for FljB and gene encoding FljA are expressed

Question 198. Whose interaction with Lex-A facilitates the repressor’s self-cleavage reaction?

Rec-A
Rec-B
Rec-C
Rec-D

Discuss Question

Answer: Option A. -> Rec-A
Answer: (a).Rec-A

Question 199. Which of the following encodes recombinase?

fliC
fljB
hin
fljA

Discuss Question

Answer: Option C. -> hin
Answer: (c).hin

Question 200. Which of the following takes place when tryptophan levels are high?

Attenuation at the attenuator structure formed by sequences of 3 and 4
Ribosomes pauses at the Try codons in sequence 1
Formation of paired structure between 2 and 3 sequences prevents attenuation
2:3 structures, unlike the 3:4 attenuator, does not prevent transcription

Discuss Question

Answer: Option A. -> Attenuation at the attenuator structure formed by sequences of 3 and 4
Answer: (a).Attenuation at the attenuator structure formed by sequences of 3 and 4