Question 1

Which of the following best describes the effect of histone acetylation on chromatin structure and gene expression?

Accepted Answer

Histone acetylation neutralizes the positive charge on lysine residues, loosening chromatin and promoting gene expression.

Question 2

A mutation in a gene's promoter region eliminates the TATA box. What is the most likely consequence for transcription initiation?

Accepted Answer

Transcription initiation will be severely reduced because TFIID cannot bind efficiently.

Question 3

Which of the following is a direct result of DNA methylation at CpG islands in promoter regions?

Accepted Answer

Recruitment of repressive chromatin remodeling complexes and decreased gene expression.

Question 4

Which chromatin remodeling mechanism is depicted when a chromatin remodeler uses ATP to slide nucleosomes along DNA, exposing previously hidden DNA sequences?

Accepted Answer

Alteration of DNA-protein contacts

Question 5

A scientist treats cells with 5-azacytidine, a base analog that cannot be methylated. What is the expected effect on gene expression?

Accepted Answer

Genes that are normally silent due to methylation may become expressed.

Question 6

Which of the following best explains how enhancers can regulate transcription from a distance?

Accepted Answer

DNA bends to bring enhancer-bound activators into contact with the transcription initiation complex.

Question 7

Which protein complex is responsible for recognizing and degrading ubiquitinated proteins in the cytoplasm?

Accepted Answer

Proteasome

Question 8

Alternative splicing of pre-mRNA can result in which of the following outcomes?

Accepted Answer

Production of multiple protein isoforms from a single gene

Question 9

Which of the following motifs is characterized by two α-helices separated by a turn, allowing DNA binding?

Accepted Answer

Helix-turn-helix

Question 10

What is the primary function of the SWI/SNF chromatin remodeling complex?

Accepted Answer

To reposition nucleosomes and make DNA accessible to transcription factors

Question 11

A mutation causes the loss of function of histone deacetylases (HDACs) in a cell. What is the most likely effect on gene expression?

Accepted Answer

Increased acetylation of histones and elevated gene expression

Question 12

Which of the following is a plausible mechanism by which DNA methylation represses gene transcription?

Accepted Answer

By inhibiting the binding of transcription factors to DNA

Question 13

Which of the following statements about RNA interference (RNAi) is correct?

Accepted Answer

RNAi involves short double-stranded RNAs that guide the degradation or translational repression of specific mRNAs.

Question 14

A gene is found to be highly expressed in liver cells but not in neurons. Which of the following mechanisms is most likely responsible for this tissue-specific expression?

Accepted Answer

Tissue-specific transcription factors binding to enhancers or promoters

Question 15

Which of the following posttranscriptional mechanisms can rapidly decrease the steady-state level of a specific mRNA in the cytoplasm?

Accepted Answer

Shortening of the poly-A tail by deadenylase enzymes

Question 16

Which of the following best describes the role of the TATA-binding protein (TBP) in transcription initiation?

Accepted Answer

TBP is a subunit of TFIID that binds to the TATA box, facilitating assembly of the transcription initiation complex.

Question 17

Which of the following is a direct effect of nonsense-mediated decay?

Accepted Answer

Rapid degradation of mRNAs containing premature stop codons

Question 18

Which of the following is NOT a typical posttranslational modification that regulates protein function?

Accepted Answer

Addition of a poly-A tail

Question 19

A mutation in the gene encoding a zinc finger transcription factor disrupts its ability to bind zinc. What is the most likely consequence?

Accepted Answer

The transcription factor will not fold properly and will fail to bind DNA.

Question 20

Which of the following best explains why eukaryotic gene regulation is more complex than prokaryotic gene regulation?

Accepted Answer

Eukaryotes have a larger amount of DNA, more chromosomes, and spatial separation of transcription and translation.

Regulation of Gene Expression in Eukaryotes: Mechanisms and Molecular Strategies

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