Q: Which equation correctly represents the directionality of RNA synthesis by RNA polymerase?

$$ \text{RNA synthesis:} \ 5' \rightarrow 3' $$

Question 1

Which of the following statements best describes the role of the promoter in transcription initiation in both prokaryotes and eukaryotes?

Accepted Answer

The promoter is a region of DNA upstream of the transcription start site that recruits RNA polymerase and determines the orientation and frequency of transcription initiation.

Question 2

In bacterial transcription, which consensus sequence is located approximately 10 base pairs upstream of the transcription start site?

Accepted Answer

The Pribnow box (TATAAT)

Question 3

Which enzyme catalyzes the formation of phosphodiester bonds during RNA synthesis, and what is the direction of synthesis?

Accepted Answer

RNA polymerase; 5′→3′

Question 4

What is the function of the sigma (σ) factor in bacterial transcription?

Accepted Answer

It binds to the -10 and -35 promoter elements and helps RNA polymerase recognize the promoter.

Question 5

Which of the following is NOT a post-transcriptional modification that occurs in eukaryotic pre-mRNA?

Accepted Answer

Addition of a Pribnow box

Question 6

A mutation in the polyadenylation signal sequence (AAUAAA) of a eukaryotic gene would most likely affect which process?

Accepted Answer

Cleavage and addition of the poly-A tail to the mRNA

Question 7

Which equation correctly represents the directionality of RNA synthesis by RNA polymerase?

Accepted Answer

$$ 	ext{RNA synthesis:} \ 5' ightarrow 3' $$

Question 8

Which of the following best explains why eukaryotic mRNA is more stable in the cytoplasm compared to prokaryotic mRNA?

Accepted Answer

Eukaryotic mRNA is protected by a 5′ cap and a poly-A tail, which prevent degradation by exonucleases.

Question 9

Which of the following is a function of introns in eukaryotic genes?

Accepted Answer

They may contain regulatory sequences and allow for alternative splicing, increasing protein diversity.

Question 10

During transcription termination in bacteria, which mechanism involves a stem-loop structure in the RNA?

Accepted Answer

Intrinsic termination (rho-independent)

Question 11

Which of the following statements about RNA polymerase in eukaryotes is correct?

Accepted Answer

RNA polymerase II synthesizes mRNA.

Question 12

Which of the following best describes the process of alternative splicing?

Accepted Answer

It allows a single gene to produce multiple mRNA variants by combining exons in different ways.

Question 13

In eukaryotic transcription, which complex is formed when RNA polymerase II and several transcription factors bind to the promoter?

Accepted Answer

Transcription initiation complex

Question 14

Which of the following is true regarding the direction of transcription relative to the promoter?

Accepted Answer

Transcription proceeds downstream from the promoter.

Question 15

Which of the following is a plausible consequence of a mutation that prevents the formation of the 5′ cap on eukaryotic mRNA?

Accepted Answer

The mRNA will be more susceptible to degradation and less efficiently translated.

Question 16

Which of the following equations represents the consensus sequence for the bacterial -10 promoter element?

Accepted Answer

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

Question 17

Which of the following statements about transcription in prokaryotes is correct?

Accepted Answer

Prokaryotes use a single RNA polymerase for all transcription.

Question 18

Which of the following is a function of the poly-A tail in eukaryotic mRNA?

Accepted Answer

It facilitates export of mRNA from the nucleus and protects it from degradation.

Question 19

Which of the following best describes the role of snRNPs in RNA splicing?

Accepted Answer

snRNPs recognize splice sites and, together with other proteins, form the spliceosome to remove introns and ligate exons.

LEC 21: Transcription and RNA Processing in Prokaryotes and Eukaryotes

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