$$\text{Acetylation} \rightarrow \text{Open Chromatin} \rightarrow \text{Increased Transcription}$$

Question 1

Which of the following best describes the role of pioneer transcription factors in gene regulation?

Accepted Answer

They bind to DNA sequences even when those sequences are wrapped in nucleosomes, initiating chromatin opening.

Question 2

Histone acetylation is associated with which of the following outcomes in eukaryotic gene regulation?

Accepted Answer

Formation of open chromatin and increased transcription initiation.

Question 3

Which enzyme is responsible for adding acetyl groups to lysine residues on histone tails?

Accepted Answer

Histone acetyltransferase (HAT)

Question 4

What is the effect of DNA methylation at CpG islands upstream of a gene?

Accepted Answer

It represses gene expression by recruiting proteins that recruit histone deacetylases.

Question 5

Which of the following equations best represents the relationship between histone acetylation and chromatin accessibility?

Accepted Answer

$$	ext{Acetylation} ightarrow 	ext{Open Chromatin} ightarrow 	ext{Increased Transcription}$$

Question 6

A scientist introduces a double-stranded RNA (dsRNA) corresponding to a gene of interest into a cell. Which process is most likely to occur?

Accepted Answer

The dsRNA will be processed by Dicer, incorporated into RISC, and lead to degradation or inhibition of the target mRNA.

Question 7

Which of the following statements about epigenetic regulation is correct?

Accepted Answer

Epigenetic marks such as histone acetylation and DNA methylation can be reversible and affect gene expression without altering DNA sequence.

Question 8

Which of the following best explains why histone acetylation leads to an open chromatin conformation?

Accepted Answer

Acetylation neutralizes the positive charge on lysine residues, reducing histone-DNA binding and making DNA more accessible.

Question 9

Which of the following is a function of microRNAs (miRNAs) in eukaryotic cells?

Accepted Answer

miRNAs bind to mRNAs and either degrade them or block their translation, reducing protein expression.

Question 10

Which of the following best describes the role of chromatin remodeling complexes in gene regulation?

Accepted Answer

They use ATP to move or eject nucleosomes, making DNA more accessible for transcription.

Question 11

A gene is found to be transcriptionally silent and DNase I-insensitive. Which chromatin state is most likely present?

Accepted Answer

Closed chromatin with deacetylated and methylated histones.

Question 12

Which of the following scenarios illustrates a real-world example of epigenetic gene regulation?

Accepted Answer

Prenatal exposure to famine results in decreased methylation of the IGF2 gene and increased risk of metabolic disorders decades later.

Question 13

Which of the following is TRUE regarding the function of histone deacetylases (HDACs)?

Accepted Answer

HDACs remove acetyl groups from histone tails, leading to chromatin closure and gene repression.

Question 14

Which of the following best describes the relationship between DNA methylation and histone modification in gene repression?

Accepted Answer

DNA methylation recruits proteins that recruit histone deacetylases, leading to closed chromatin and gene repression.

Question 15

Which of the following equations represents the effect of miRNA on gene expression?

Accepted Answer

$$	ext{miRNA} + 	ext{mRNA} ightarrow 	ext{mRNA degradation or translation inhibition} ightarrow 	ext{Decreased protein expression}$$

Question 16

Which of the following is a plausible outcome of introducing siRNA targeting a specific gene in a laboratory experiment?

Accepted Answer

The gene's mRNA will be degraded, resulting in reduced protein expression and allowing researchers to study the phenotype.

Question 17

Which of the following best describes the function of chromatin reader proteins?

Accepted Answer

They bind to modified histones and recruit chromatin remodeling complexes to alter chromatin accessibility.

Question 18

Which of the following is NOT a mechanism by which eukaryotic transcription factors increase the rate of transcription initiation?

Accepted Answer

Recruiting DNA methyltransferases to activate gene expression.

Question 19

Which of the following best explains the reversibility of epigenetic marks?

Accepted Answer

For every enzyme that adds a chromatin modification, there is another enzyme that removes it.

Regulation of Gene Expression in Eukaryotes: Chromatin, Epigenetics, and Small RNAs

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