Molecular Biology Multiple Choice Questions on “Genes Are Expressed by Making RNA – 1”.
1. How is the genetic material expressed?
A. By replication and transcription
B. By transcription and translation
C. By translation and modification
D. By mutation and transposition
Answer: B
Explanation: Expression of the genetic material is the series of processes of how the sequence of bases in the DNA directs the production of the RNAs and proteins that perform cellular functions and define cellular identity. The basic processes responsible for gene expression are transcription and RNA processing followed by a translation.
2. RNA polymerase requires a DNA primer for RNA synthesis.
A. True
B. False
Answer: B
Explanation: RNA polymerase does not require any primer for RNA synthesis. It can start transcription of the DNA template de novo.
3. The transcription process carried out by the RNA polymerase is very accurate but less accurate than replication.
A. True
B. False
Answer: A
Explanation: Transcription, though accurate, is less accurate than replication. One mistake occurs in every 10,000 nucleotides added in transcription, compared to 10,000,000 nucleotides for replication. This difference reflects the lack of extensive proofreading mechanism for transcription, although two forms of proofreading for RNA synthesis do exist.
4. Which of the following RNA polymerases are responsible for the production of 5S rRNA?
A. RNA polymerase I
B. RNA polymerase II
C. RNA polymerase III
D. RNA polymerase IV
Answer: C
Explanation: Polymerase I is responsible for the transcription of the different types of rRNA except for the 5S rRNA. 5S rRNA is transcribed by polymerase III along with some small nuclear RNA genes and the tRNAs.
5. Which RNA polymerase deals with the production of mRNA?
A. RNA polymerase I
B. RNA polymerase II
C. RNA polymerase III
D. RNA polymerase IV
Answer: A
Explanation: Polymerase I is responsible for the transcription of the different types of rRNA except for the 5S rRNA. 5S rRNA is transcribed by polymerase III along with some small nuclear RNA genes and the tRNAs. Polymerase II deals with the transcription of the mRNAs.
6. The eukaryotic subunit of RNA polymerase homologous to the ω subunit of bacterial RNA polymerase is ___________
A. RPA1
B. RPB2
C. RPC5
D. RPB6
Answer: D
Explanation: The eukaryotic subunit of RNA polymerase homologous to the ω subunit of bacterial RNA polymerase is RPB6. RPA1, RPB2 and RPC5 subunits of eukaryotic RNA polymerase are homologous to the bacterial RNA polymerase subunits β’, β and αI respectively.
7. The E. coli RNA polymerase adds __________ nucleotides per second.
A. 20
B. 30
C. 40
D. 50
Answer: C
Explanation: The E. coli RNA polymerase can synthesize RNA at a rate of 40 nucleotides per second. For proper functioning of the RNA polymerase enzyme Mg2+ ion and an optimum temperature of 37˚C is required.
8. The RNA polymerase holoenzyme has the structural formula of ___________
A. α2ββ’ωσ
B. αβ2β’ωσ
C. α2ββ’ω
D. α2ββ’σ
Answer: A
Explanation: In a complete RNA polymerase, called the holoenzyme there are 5 subunits. Of which two are α and one of the each of the other 4 subunits namely β, β’, ω and σ.
9. Which of the following statements are true about the roles of RNA polymerase subunits?
i. α subunit is encoded by “rpo A” gene, required for core protein assembly. ii. β subunit is encoded by “rpo C” gene is the catalytic center of RNA polymerase. iii. ω subunit is encoded by “rpo Z” gene and helps in proper association of all the subunits. iv. σ factor is encoded by “rpo D” gene and contributes in promoter recognition.
A. i, ii, iii
B. ii, iii, iv
C. i, iii, iv
D. i, ii, iii, iv
Answer: C
Explanation: The β subunit of the RNA polymerase is coded by “rpo B” gene. The β’ subunit is known to be encoded by “rpo C gene.
10. The α subunits of polymerase has a function of ____________
A. Promoter binding
B. Initiation
C. Elongation
D. Termination
Answer: A