Question 1

Which of the following best describes the main function of messenger RNA (mRNA) in cells?

Accepted Answer

It acts as a short-lived intermediary that carries genetic information from DNA to the site of protein synthesis.

Question 2

Which base pairing occurs during RNA synthesis from a DNA template?

Accepted Answer

A with U, C with G

Question 3

Which of the following is NOT a function of the 5' cap added to eukaryotic pre-mRNA?

Accepted Answer

Initiating DNA replication

Question 4

A mutation in the Pribnow box (–10 consensus sequence) of a bacterial promoter would most likely affect which process?

Accepted Answer

Recognition and binding of RNA polymerase to the promoter

Question 5

Which enzyme is responsible for catalyzing the formation of phosphodiester bonds during RNA synthesis?

Accepted Answer

RNA polymerase

Question 6

What is the role of the sigma ($$ \sigma ) $$subunit in bacterial RNA polymerase?

Accepted Answer

It recognizes and binds to promoter sequences, allowing initiation of transcription.

Question 7

Which of the following sequences is the consensus sequence for the Pribnow box in bacterial promoters?

Accepted Answer

$$5'	ext{-}TATAAT	ext{-}3'$$

Question 8

Which of the following best describes intrinsic termination of transcription in bacteria?

Accepted Answer

It depends on an inverted repeat sequence that forms a hairpin structure in the mRNA.

Question 9

Which of the following is a key difference between bacterial and eukaryotic transcription?

Accepted Answer

Eukaryotes have three distinct RNA polymerases, each transcribing different classes of genes.

Question 10

A researcher treats E. coli with rifampicin. What is the most likely outcome?

Accepted Answer

The bacteria will be unable to synthesize mRNA, tRNA, or rRNA.

Question 11

Which of the following is true regarding the coding and template strands of DNA during transcription?

Accepted Answer

The template strand is complementary to the RNA transcript.

Question 12

Which of the following is a function of small nuclear RNA (snRNA)?

Accepted Answer

It plays a role in mRNA processing in the nucleus.

Question 13

Which of the following best explains why eukaryotic mRNA is more stable than bacterial mRNA?

Accepted Answer

Eukaryotic mRNA undergoes posttranscriptional modifications such as 5' capping and 3' polyadenylation.

Question 14

Which of the following is a plausible consequence of a mutation that disrupts the –35 consensus sequence in a bacterial promoter?

Accepted Answer

RNA polymerase binding to the promoter will be reduced, decreasing transcription initiation.

Question 15

Which of the following best describes the role of alternative sigma subunits in E. coli?

Accepted Answer

They allow the core RNA polymerase to recognize different promoter sequences for different sets of genes.

Question 16

Which of the following is a direct result of the formation of a hairpin structure in mRNA during bacterial transcription?

Accepted Answer

Intrinsic termination of transcription

Question 17

Which of the following is true about the process of chain elongation during bacterial transcription?

Accepted Answer

The sigma subunit dissociates after the first 8–10 nucleotides are joined.

Question 18

Which of the following is a real-world application of understanding bacterial transcription mechanisms?

Accepted Answer

Designing antibiotics like rifampicin that target bacterial RNA polymerase.

Question 19

Which of the following is a plausible effect of a mutation that prevents the formation of the open promoter complex during bacterial transcription initiation?

Accepted Answer

Transcription initiation will fail because the DNA will not be unwound.

Question 20

Which of the following best describes the relationship between the coding strand of DNA and the RNA transcript produced during transcription?

Accepted Answer

They are identical except that RNA contains uracil instead of thymine.

Molecular Biology of Transcription and RNA Processing: Study Notes

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