Question 1

Which of the following best describes the effect of histone acetylation on gene expression in eukaryotic cells?

Accepted Answer

Histone acetylation loosens chromatin, activating gene transcription.

Question 2

A mutation prevents the addition of the 5' cap to pre-mRNA in a eukaryotic cell. Which of the following is the most likely consequence?

Accepted Answer

The mRNA will be rapidly degraded by exonucleases.

Question 3

Which enzyme complex is primarily responsible for shifting nucleosomes to expose gene promoters for transcription activation?

Accepted Answer

SWI/SNF complex

Question 4

In the context of alternative splicing, which scenario best explains how a single gene can produce multiple protein isoforms?

Accepted Answer

Different combinations of exons are included in the mature mRNA.

Question 5

Which of the following post-translational modifications is most directly associated with targeting proteins for degradation via the proteasome?

Accepted Answer

Ubiquitination

Question 6

A researcher observes that a gene is heavily methylated at its promoter region. What is the most likely effect on this gene's expression?

Accepted Answer

The gene will be transcriptionally silenced.

Question 7

Which of the following best describes the role of microRNAs (miRNAs) in gene regulation?

Accepted Answer

They bind to mRNA and block translation or promote degradation.

Question 8

Which of the following is a key difference between gene regulation in prokaryotes and eukaryotes?

Accepted Answer

Eukaryotes use chromatin structure to regulate gene accessibility, while prokaryotes do not.

Question 9

A patient has a mutation in the gene encoding a general transcription factor (GTF) such as TFIID. Which process is most directly affected?

Accepted Answer

Assembly of the transcription machinery at the promoter

Question 10

Which of the following best explains why phosphorylation of the transcription factor CREB increases gene expression?

Accepted Answer

Phosphorylation activates CREB, allowing it to recruit coactivators and RNA polymerase II.

Question 11

Which of the following is a direct result of the removal of the poly(A) tail from an mRNA molecule?

Accepted Answer

The mRNA becomes more susceptible to exonuclease degradation.

Question 12

Which of the following mechanisms allows for the silencing of transposable elements and viral genes in eukaryotic cells?

Accepted Answer

RNA interference (RNAi) via siRNAs

Question 13

A scientist discovers a new protein that binds to the 3' UTR of specific mRNAs and accelerates their degradation. This protein most likely functions in which regulatory process?

Accepted Answer

Post-transcriptional regulation

Question 14

Which of the following is a consequence of intron retention during alternative splicing?

Accepted Answer

The mature mRNA may contain a premature stop codon, leading to nonsense-mediated decay.

Question 15

Which of the following best describes the function of the DNA-binding domain (DBD) of a transcription factor?

Accepted Answer

It allows the transcription factor to bind to specific DNA sequences in promoters or enhancers.

Question 16

Which of the following is a real-world example of epigenetic regulation affecting gene expression?

Accepted Answer

X-chromosome inactivation in female mammals via DNA methylation

Question 17

A mutation in the gene encoding the enzyme responsible for adding the poly(A) tail to mRNA would most likely result in which of the following?

Accepted Answer

Decreased mRNA stability and reduced translation efficiency

Question 18

Which of the following statements about the role of enhancers in eukaryotic gene regulation is correct?

Accepted Answer

Enhancers can act over long distances to increase transcription of specific genes.

Question 19

Which of the following post-translational modifications is most likely to alter the subcellular localization of a protein?

Accepted Answer

Lipidation (e.g., prenylation or palmitoylation)

Eukaryotic Gene Regulation: Mechanisms and Levels of Control (10.1)

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