Question 1

Which of the following best describes epigenetics?

Accepted Answer

Heritable changes in gene expression that do not involve changes to the DNA sequence.

Question 2

DNA methylation most commonly occurs at which specific DNA sequence?

Accepted Answer

CpG site, where a cytosine is followed by a guanine.

Question 3

Which enzyme is responsible for adding methyl groups to DNA during epigenetic regulation?

Accepted Answer

DNA methyltransferase (DNMT)

Question 4

What is the effect of DNA methylation at promoter regions?

Accepted Answer

Transcriptional repression

Question 5

Which histone modification is generally associated with transcriptional activation?

Accepted Answer

Acetylation by histone acetyltransferases (HATs)

Question 6

A researcher finds that a tumor suppressor gene in a cancer cell line is heavily methylated at its promoter. What is the most likely consequence?

Accepted Answer

Reduced expression of the tumor suppressor gene, contributing to cancer progression.

Question 7

Which of the following is NOT a major mechanism of epigenetic regulation?

Accepted Answer

Alternative splicing of mRNA

Question 8

Histone methylation at H3K4me3 is generally associated with which chromatin state?

Accepted Answer

Transcriptionally active euchromatin

Question 9

Which type of non-coding RNA is involved in X-chromosome inactivation?

Accepted Answer

Long noncoding RNA (lncRNA), such as XIST

Question 10

A patient is treated with 5-azacytidine, a DNMT inhibitor. What is the expected effect on gene expression?

Accepted Answer

Decreased DNA methylation, leading to increased expression of previously silenced genes.

Question 11

Which of the following best explains why nerve and muscle cells have different functions despite having the same DNA?

Accepted Answer

They have different patterns of epigenetic marks that regulate gene expression.

Question 12

Which histone modification is most likely to result in condensed, transcriptionally inactive chromatin?

Accepted Answer

Deacetylation by HDACs

Question 13

Which of the following equations represents the addition of a methyl group to cytosine by DNMT?

Accepted Answer

$$\mathrm{Cytosine} + \mathrm{CH}_3 \xrightarrow{DNMT} \mathrm{5	ext{-}methylcytosine}$$

Question 14

Which of the following is a plausible consequence of environmental factors such as diet or smoking on epigenetic regulation?

Accepted Answer

Altered DNA methylation patterns that may increase disease risk.

Question 15

MicroRNAs (miRNAs) regulate gene expression by which mechanism?

Accepted Answer

Binding to mRNA to block translation or promote degradation.

Question 16

A scientist observes increased H3K9me3 marks in neurons of patients with a neurodegenerative disease. What is the most likely effect?

Accepted Answer

Transcriptional silencing of genes important for neuronal function.

Question 17

Which therapeutic approach targets histone deacetylases to treat cancer?

Accepted Answer

HDAC inhibitors

Question 18

Which of the following statements about chromatin structure is correct?

Accepted Answer

Euchromatin is transcriptionally active and less condensed than heterochromatin.

Question 19

Which multi-step process best describes the role of long noncoding RNAs (lncRNAs) in epigenetic regulation?

Accepted Answer

lncRNAs recruit chromatin modifiers to specific genomic regions, leading to changes in histone modifications and altered gene expression.

Epigenetic Regulation of Gene Expression: Mechanisms and Implications

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