Question 1

Which of the following best describes the role of histone acetylation in gene expression regulation in eukaryotes?

Accepted Answer

Histone acetylation adds acetyl groups to histones, resulting in decondensed chromatin and increased transcription.

Question 2

A researcher observes that a gene is not being expressed in a cell. Upon investigation, they find that the DNA in this region is heavily methylated. What is the most likely explanation for this observation?

Accepted Answer

DNA methylation is associated with transcriptional silencing by promoting chromatin condensation.

Question 3

Which of the following mechanisms is unique to eukaryotic gene regulation and not found in prokaryotes?

Accepted Answer

Alternative splicing of pre-mRNA

Question 4

A mutation prevents the addition of ubiquitin to a protein. What is the most likely consequence for that protein?

Accepted Answer

The protein will accumulate in the cell because it is not targeted for degradation.

Question 5

Which of the following best explains how alternative splicing increases protein diversity in eukaryotes?

Accepted Answer

It allows for the removal of exons, resulting in different mature mRNAs from the same gene.

Question 6

In the context of epigenetics, which statement is correct?

Accepted Answer

Epigenetic modifications such as DNA methylation can be inherited across generations.

Question 7

Which of the following is a direct result of miRNA binding to a target mRNA with perfect complementarity?

Accepted Answer

The mRNA is cleaved and degraded, preventing translation.

Question 8

Which of the following best describes the difference between heterochromatin and euchromatin?

Accepted Answer

Heterochromatin is highly condensed and transcriptionally inactive, while euchromatin is less condensed and transcriptionally active.

Question 9

A scientist treats cells with a histone deacetylase (HDAC) inhibitor. What is the expected effect on gene expression?

Accepted Answer

Gene expression will increase due to chromatin decondensation.

Question 10

Which of the following steps is NOT a point of gene expression regulation in eukaryotes?

Accepted Answer

Protein folding in the endoplasmic reticulum

Question 11

A patient is exposed to a toxin that increases DNA methylation in liver cells. What is the most likely effect on gene expression in these cells?

Accepted Answer

Decreased gene expression due to chromatin condensation.

Question 12

Which of the following is true regarding the proteasome?

Accepted Answer

It degrades proteins that have been tagged with ubiquitin.

Question 13

Which of the following is a similarity between gene regulation in bacteria and eukaryotes?

Accepted Answer

Both can regulate gene expression at the level of transcription initiation.

Question 14

A gene is found to be highly expressed in muscle cells but not in liver cells. Which mechanism most likely explains this tissue-specific expression?

Accepted Answer

Different transcription factors are present in muscle and liver cells, activating the gene only in muscle cells.

Question 15

Which of the following best describes the function of the RISC complex in RNA interference?

Accepted Answer

RISC binds to miRNA and guides it to complementary mRNA, leading to mRNA degradation or translation inhibition.

Question 16

Which of the following scenarios illustrates a real-world application of epigenetics?

Accepted Answer

A pregnant woman exposed to famine has children and grandchildren with altered gene expression due to changes in DNA methylation.

Question 17

Which of the following is the correct sequence of events for transcription initiation in eukaryotes?

Accepted Answer

Chromatin remodeling exposes the promoter, transcription factors bind, then RNA polymerase assembles at the core promoter.

Question 18

Which of the following equations best represents the process of protein degradation by the ubiquitin-proteasome system?

Accepted Answer

$$	ext{Protein} + n\,	ext{Ubiquitin} ightarrow 	ext{Ubiquitinated Protein} \xrightarrow{	ext{Proteasome}} 	ext{Peptides} + n\,	ext{Ubiquitin}$$

Control of Gene Expression in Eukaryotes

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