Question 1

Which of the following best describes the role of chromatin-remodelling complexes such as SWI-SNF in gene expression?

Accepted Answer

They destabilize chromatin structure to allow transcription factors access to DNA.

Question 2

What is the effect of histone acetylation on chromatin structure and gene expression?

Accepted Answer

It opens chromatin, increasing accessibility for transcription factors and promoting gene expression.

Question 3

Which enzyme is responsible for adding acetyl groups to histone tails, and what is the result?

Accepted Answer

HAT; chromatin becomes more open

Question 4

A researcher treats cells with a histone deacetylase (HDAC) inhibitor. What is the most likely outcome for gene expression?

Accepted Answer

Gene expression will increase due to chromatin relaxation.

Question 5

Which of the following statements about epigenetics is correct?

Accepted Answer

Epigenetic modifications are reversible and affect gene expression without altering DNA sequence.

Question 6

Transcriptionally active DNA is characterized by which of the following features?

Accepted Answer

DNase hypersensitive sites and accessible promoters

Question 7

Which process is directly reversed by histone deacetylases (HDACs)?

Accepted Answer

Histone acetylation

Question 8

A mutation in the SWI-SNF complex that prevents ATP binding would most likely result in:

Accepted Answer

Decreased chromatin accessibility and lower gene expression

Question 9

Which of the following best explains why histone acetylation is considered an epigenetic modification?

Accepted Answer

It is a reversible chemical modification that affects gene expression without altering DNA sequence.

Question 10

If a gene is located in a region of chromatin that is highly condensed, which of the following is most likely true?

Accepted Answer

The gene is silenced due to inaccessibility of transcription factors.

Question 11

Which of the following equations best represents the reversible nature of histone acetylation?

Accepted Answer

$$\mathrm{Histone} + \mathrm{Acetyl~group} \xrightleftharpoons[\mathrm{HDAC}]{\mathrm{HAT}} \mathrm{Acetylated~histone}$$

Question 12

A patient’s cells show abnormally high levels of histone deacetylation. Which of the following is a likely consequence?

Accepted Answer

Decreased transcription due to chromatin condensation

Question 13

Which of the following is NOT a feature of epigenetic regulation?

Accepted Answer

Change in DNA sequence

Question 14

Which of the following scenarios best illustrates the effect of DNA packaging on transcription factor access?

Accepted Answer

A gene in euchromatin is easily accessed by transcription factors.

Question 15

Which of the following statements about histone acetyltransferases (HATs) is correct?

Accepted Answer

HATs add acetyl groups to specific lysines on histone tails.

Question 16

Which of the following is a direct consequence of histone acetylation at promoter regions?

Accepted Answer

Recruitment of activators and increased transcription

Question 17

A scientist observes that a gene is highly expressed only after treatment with a chromatin-remodelling complex. What is the most likely explanation?

Accepted Answer

The complex destabilized chromatin, allowing transcription factors to access the promoter.

Question 18

Which of the following best describes the relationship between histone acetylation and transcription?

Accepted Answer

Histone acetylation leads to chromatin relaxation and transcriptional activation.

Question 19

Which of the following is a multi-step process that leads to increased gene expression?

Accepted Answer

Histone acetylation by HATs, chromatin relaxation, and transcription factor binding

Chromatin Structure, Histone Modifications, and Epigenetic Regulation of Gene Expression

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