Question 1

Which of the following best describes the role of the sigma (σ) factor in prokaryotic transcription initiation?

Accepted Answer

It recognizes and binds to the promoter sequence, allowing RNA polymerase to initiate transcription.

Question 2

During eukaryotic mRNA processing, which modification is essential for protecting the mRNA from exonuclease degradation and facilitating ribosome binding?

Accepted Answer

Addition of a 7-methylguanosine cap at the 5' end

Question 3

Which of the following sequences is most likely to be found at the -10 position of a bacterial promoter?

Accepted Answer

$$	ext{TATAAT}$$

Question 4

A mutation in the polyadenylation signal (AAUAAA) of a eukaryotic gene would most likely result in which of the following?

Accepted Answer

Improper cleavage and polyadenylation of the pre-mRNA, leading to unstable or untranslatable mRNA

Question 5

Which of the following statements about RNA polymerase is FALSE?

Accepted Answer

RNA polymerase requires a primer to initiate synthesis.

Question 6

In eukaryotic cells, which RNA polymerase is responsible for synthesizing mRNA?

Accepted Answer

RNA polymerase II

Question 7

Which of the following best explains the evolutionary advantage of introns in eukaryotic genes?

Accepted Answer

They enable alternative splicing, increasing protein diversity from a single gene.

Question 8

A researcher observes that a certain eukaryotic gene can produce multiple protein isoforms. Which process most directly explains this observation?

Accepted Answer

Alternative splicing of exons

Question 9

Which of the following is a function of the spliceosome in eukaryotic cells?

Accepted Answer

It removes introns from pre-mRNA and joins exons together.

Question 10

Which of the following best describes the difference between intrinsic and Rho-dependent termination in prokaryotic transcription?

Accepted Answer

Intrinsic termination involves the formation of a hairpin structure in the RNA, while Rho-dependent termination requires the Rho protein to dissociate the RNA from the DNA template.

Question 11

A patient has a mutation that prevents the addition of the 5' cap to mRNA. Which of the following is a likely consequence?

Accepted Answer

The mRNA will be rapidly degraded and translation initiation will be impaired.

Question 12

Which of the following is TRUE regarding the directionality of transcription?

Accepted Answer

The DNA template strand is read in the 3' to 5' direction, while RNA is synthesized in the 5' to 3' direction.

Question 13

Which of the following best describes the function of general transcription factors in eukaryotic transcription?

Accepted Answer

They are essential for the binding of RNA polymerase II to the promoter and initiation of transcription.

Question 14

Which of the following is an example of RNA editing that can result in tissue-specific protein products, as seen in the processing of apolipoprotein mRNA?

Accepted Answer

A cytosine is edited to uracil, creating a stop codon in the intestine but not in the liver.

Question 15

Which of the following is a direct result of the deamination of cytosine in RNA editing?

Accepted Answer

Formation of uracil

Question 16

A gene contains the following sequence: 5'-TACCGTAACTCG-3' (coding strand). What is the sequence of the mRNA transcribed from this gene?

Accepted Answer

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

Question 17

Which of the following is NOT a function of the polyA tail added to eukaryotic mRNA?

Accepted Answer

Initiating translation by binding to the ribosome

Question 18

Which of the following best explains why both DNA strands can serve as templates for transcription?

Accepted Answer

The template strand is determined by the orientation of the promoter for each gene.

Question 19

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

Accepted Answer

Eukaryotic transcription involves chromatin remodeling and more complex cis- and trans-acting factors.

Transcription and Post-Transcriptional Processing in Eukaryotes and Prokaryotes

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