This set of Life Sciences Multiple Choice Questions & Answers (MCQs) focuses on “Transcription”.
1. The process of formation of RNA is known as___________
b) DNA repair
Explanation: Transcription is a process of formation of the transcript or RNA with the help of RNA polymerase.
2. Like replication, transcription also occurs bidirectionally.
Explanation: Transcription occurs unidirectionally and synthesized RNA chain from 5’ to 3’ direction.
3. Mark the statement which is INCORRECT about the transcription unit?
a) It is a transcribed segment of DNA
b) Eukaryotes have monocistronic transcription unit
c) Prokaryotes also have a monocistronic transcription unit
d) Immediate product of transcription is primary transcript
Explanation: Transcription unit is the transcribed segment of DNA. If the transcription unit carries information of one gene, it is called monocistronic while a set of adjacent genes when transcribed as a unit called polycistronic.
4. Name the site where upstream sequences located?
a) Prior to start point
b) After the startpoint
c) Right border of DNA
d) In the middle of DNA
Explanation: Start point is the first base pair from which transcription starts. Upstream sequences are located prior to the start point while sequences after the start point are called downstream of it.
5. Which of the following is TRUE for the RNA polymerase activity?
a) DNA dependent DNA synthesis
b) Direct repair
c) DNA dependent RNA synthesis
d) RNA dependent RNA synthesis
Explanation: RNA polymerase is also known as DNA dependent RNA polymerase enzyme and it involves a synthesis of RNA from DNA.
6. Who discovered RNA polymerase?
a) Samuel B. Weiss
c) Watson and Crick
Explanation: Samuel B. Weiss and Jerard Hurwitz in 1960 discovered RNA polymerase. RNA polymerase is also known as DNA dependent.
7. Which of the following ensure stable binding of RNA polymerase at the promoter site?
a) DNA photolyase
b) Sigma factor
c) DNA glycosylase
Explanation: Sigma factor decreases the binding of the core enzyme to non-specific DNA sequences and increases binding to the promoter.
8. What is the work of the sigma factor in transcription?
a) Helicase action
b) Transcription initiation
c) Transcription elongation
d) Transcription termination
Explanation: Sigma factor is only involved in transcription initiation not in elongation. The sigma factor is released from the core enzyme when the transcript reaches more than 8-9 nucleotide.
9. Name the sigma factor which is used for promoter recognition?
a) Sigma 32
b) Sigma 70
c) Sigma 60
d) Sigma 40
Explanation: There are 7 different types of sigma factors have been reported in E. coli but the most common is sigma 70.
10. Which of the following is used to describe the time taken by RNA polymerase to leave the promoter?
a) Promoter clearance time
b) Abortive initiation
c) Elongation factor
d) Mean time
Explanation: Promoter clearance time is the time taken by RNA polymerase core enzyme to leave the promoter. More the efficient promoter sequences, lesser would be the promoter clearance time.
11. How many base pairs of DNA is transcribed by RNA polymerase in one go?
Explanation: The RNA polymerase core enzyme moves along the template strand at uneven base i.e, moves over 7-8 base pairs in one go.
12. Which of the following transcription termination technique has RNA dependent ATPase activity?
a) Intercalating agents
b) Rho dependent
c) Rho independent
Explanation: The rho factor functions as a Hexamer and has an RNA binding site and is responsible for the termination of transcription. It has RNA dependent ATPase activity.
13. Name the one intrinsic terminator of transcription.
a) Intercalating agents
b) Rho independent
c) Rho dependent
d) Acridine orange
Explanation: Rho independent transcription termination is also known as intrinsic terminators and about 50% of E. coli genes have these types of terminators.
14. Mark the one, which is NOT the transcription inhibitor in eukaryotes.
b) Acridine dye
c) Actinomycin D
d) Rho factor
Explanation: Rifampicin inhibits beta subunit of RNA polymerase II while acridine orange and actinomycin D is used to block elongation.
Sanfoundry Global Education & Learning Series – Life Sciences.
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