Question 1

Which of the following best describes the role of the Holliday junction in homologous recombination?

Accepted Answer

It is a crossed structure that facilitates the exchange or repair of DNA between homologous chromosomes.

Question 2

During bacterial transcription, which sequence is typically found about 10 base pairs upstream of the transcription start site?

Accepted Answer

TATAAT (the -10 sequence or Pribnow box)

Question 3

Which enzyme catalyzes the formation of phosphodiester bonds between ribonucleoside triphosphates (NTPs) during transcription?

Accepted Answer

RNA polymerase

Question 4

In prokaryotes, what allows translation of mRNA to begin before transcription is complete?

Accepted Answer

The lack of compartmentalization between transcription and translation

Question 5

Which of the following is TRUE regarding RNA polymerase proofreading?

Accepted Answer

RNA polymerase can remove incorrect nucleotides through backtracking and excision.

Question 6

A mutation in the sigma factor of bacterial RNA polymerase would most likely affect which stage of transcription?

Accepted Answer

Initiation

Question 7

Which of the following best explains gene conversion during homologous recombination?

Accepted Answer

Repair of a broken chromosome using the homologous sequence, resulting in identical sequences even if alleles were different.

Question 8

Which of the following is a property unique to eukaryotic transcription compared to prokaryotic transcription?

Accepted Answer

Three distinct RNA polymerases transcribe different classes of RNA.

Question 9

What is the function of the TATA-binding protein (TBP) in eukaryotic transcription?

Accepted Answer

It recognizes and binds to the TATA box in the promoter region to initiate transcription.

Question 10

Which of the following sequences is most likely to be found in a strong bacterial promoter associated with rRNA genes?

Accepted Answer

UP element

Question 11

During transcription elongation, which direction is the RNA chain synthesized?

Accepted Answer

$$5' \rightarrow 3'$$

Question 12

Which of the following is a consequence of the formation of a GC-rich hairpin loop in bacterial transcription termination?

Accepted Answer

It causes the RNA molecule to dissociate from the DNA template.

Question 13

Which eukaryotic RNA polymerase is responsible for synthesizing mRNA?

Accepted Answer

RNA polymerase II

Question 14

A researcher finds a mutation in the DPE element of a eukaryotic gene. Which type of core promoter is most likely affected?

Accepted Answer

DPE-driven promoter

Question 15

Which of the following best describes the role of transcription factors (TFs) in eukaryotic transcription?

Accepted Answer

They regulate gene expression by binding specific DNA sequences and interacting with the transcription machinery.

Question 16

Which of the following is TRUE about the process of abortive synthesis during transcription initiation?

Accepted Answer

RNA polymerase repeatedly produces and releases short RNA fragments while still bound to the promoter.

Question 17

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

Accepted Answer

Translation can begin on an mRNA molecule before transcription is finished.

Question 18

A bacterial cell is exposed to a mutation that prevents the formation of the -35 sequence in its promoters. What is the most likely outcome?

Accepted Answer

Transcription initiation will be impaired due to reduced sigma factor binding.

Question 19

Which of the following is a key difference between the termination of transcription by RNA polymerase I and RNA polymerase II in eukaryotes?

Accepted Answer

RNA polymerase I terminates at a short run of U's without protein factors, while RNA polymerase II transcripts are cleaved at a site downstream of an AAUAAA sequence.

Question 20

Which of the following equations correctly represents the direction of RNA synthesis by RNA polymerase?

Accepted Answer

$$5' \rightarrow 3'$$

DNA Recombination and Transcription Mechanisms in Prokaryotes and Eukaryotes

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