This set of Biochemistry Multiple Choice Questions & Answers (MCQs) focuses on “DNA-Dependent Synthesis of RNA”.
1. Transcription is catalyzed by ____________
a) DNA-dependent RNA polymerases
b) RNA-dependent DNA polymerases
c) Reverse transcriptases
d) DNA ligases
View Answer
Explanation: Transcription is catalyzed by DNA-dependent RNA polymerases, which use ribonucleotide 5’-triphosphates to synthesize RNA complementary to the template strand of duplex DNA.
2. Where does RNA polymerase bind DNA?
a) Promoter
b) Operator
c) Enhancer
d) None of the mentioned
View Answer
Explanation: Transcription initiation occurs when RNA polymerase binds at specific DNA sequences called promoters.
3. Which of the following is true about RNA synthesis?
a) Synthesis of RNA is always in the 5’ to 3’ direction
b) RNA polymerase requires a primer for initiating transcription
c) U is inserted opposite T in transcription
d) New nucleotides are added on the 2’-OH of the ribose sugar
View Answer
Explanation: Unlike DNA polymerase, RNA polymerase does not require a primer to initiate transcription.
4. What is the role of sigma factor in bacterial RNA polymerase?
a) Catalyzing RNA synthesis
b) Positioning RNA polymerase correctly on the DNA template
c) Terminating RNA synthesis
d) Unwinding DNA template
View Answer
Explanation: Sigma factor enables specific binding of RNA polymerase to promoter.
5. TBP stands for?
a) TATA box polymerase
b) TATA-box binding protein
c) Transcription associated factor
d) Transcription factor binding protein
View Answer
Explanation: TBP stands for TATA-box binding protein.
6. Actinomycin D is an inhibitor of ____________
a) Transcription
b) Translation
c) Replication
d) None of the mentioned
View Answer
Explanation: The elongation of RNA strands by RNA polymerase in both bacteria and eukaryotes is inhibited by the antibiotic actinomycin D.
7. Number of hydrogen bonds that form between U and A in a Watson-Crick base pair interactions?
a) 0
b) 1
c) 2
d) 3
View Answer
Explanation: According to Watson-Crick base pair interactions, number of hydrogen bonds between U and A are 2 and between G and C are 3.
8. Repressors bind to ____________
a) Promoter
b) Enhancer
c) Operator
d) Hormone response element
View Answer
Explanation: A repressor molecule binds to the operator.
9. RNA primer is removed from the Okazaki fragment by ____________
a) DNA polymerase I
b) DNA polymerase II
c) DNA polymerase III
d) RNA polymerase
View Answer
Explanation: DNA polymerase I remove RNA primer from Okazaki fragment.
10. Binding of the prokaryotic DNA dependent RNA polymerase to promoter site is inhibited by ____________
a) Rifampicin
b) Tetracycline
c) Puromycin
d) Streptomycin
View Answer
Explanation: Rifampicin inhibits the binding of the prokaryotic DNA dependent RNA polymerase to the promoter site.
Sanfoundry Global Education & Learning Series – Biochemistry.
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