Question 1

Which of the following best describes the primary difference in gene regulation between prokaryotes and eukaryotes?

Accepted Answer

Eukaryotes regulate gene expression at multiple levels, including chromatin remodeling, transcription, RNA processing, translation, and post-translation, while prokaryotes primarily regulate at the transcriptional level.

Question 2

DNA methylation typically occurs at which sequence, and what is its effect on gene expression?

Accepted Answer

At CpG sites, leading to chromatin condensation and decreased gene expression.

Question 3

Which of the following best explains the role of histone acetylation in gene regulation?

Accepted Answer

Histone acetylation by histone acetyltransferases (HATs) adds acetyl groups to histones, resulting in decondensed chromatin and increased accessibility for transcription.

Question 4

A mutation causes the loss of function of a histone deacetylase (HDAC) enzyme in a eukaryotic cell. What is the most likely effect on gene expression?

Accepted Answer

Increased gene expression due to persistent histone acetylation and decondensed chromatin.

Question 5

Which of the following is an example of epigenetic inheritance?

Accepted Answer

Transmission of DNA methylation patterns from parent to offspring, affecting gene expression without altering the DNA sequence.

Question 6

Which of the following best describes the function of enhancers in eukaryotic gene regulation?

Accepted Answer

Enhancers are DNA sequences that can be located far from the promoter and increase transcription when bound by activator proteins.

Question 7

A researcher moves an enhancer sequence from upstream to downstream of a gene, and transcription still increases when the enhancer is bound by activators. What does this demonstrate about enhancers?

Accepted Answer

Enhancers can function regardless of their orientation or position relative to the gene.

Question 8

Which of the following is NOT a stage at which gene regulation can occur in eukaryotes?

Accepted Answer

DNA replication

Question 9

Alternative splicing allows a single gene to:

Accepted Answer

Produce multiple different proteins by including or excluding different exons in the final mRNA.

Question 10

Which of the following best describes the role of small interfering RNAs (siRNAs) in gene regulation?

Accepted Answer

siRNAs bind to complementary mRNA sequences and promote their degradation, blocking translation.

Question 11

A scientist is studying a gene with a TATA box in its promoter region. What is the primary function of the TATA box?

Accepted Answer

It serves as a binding site for the TATA-binding protein (TBP), which is essential for assembling the transcription initiation complex.

Question 12

Which of the following statements about chromatin remodeling complexes is correct?

Accepted Answer

They use energy from ATP to reposition or remove histones, making DNA accessible for transcription.

Question 13

A patient has a mutation in a tumor suppressor gene that prevents it from activating DNA repair genes. What is a likely consequence of this mutation?

Accepted Answer

Increased risk of cancer due to accumulation of DNA damage.

Question 14

Which of the following best explains why recombinant DNA technology can be used to produce human insulin in E. coli?

Accepted Answer

The genetic code is nearly universal, allowing E. coli to express human genes inserted into plasmids.

Question 15

Which of the following is a function of promoter-proximal elements in eukaryotic gene regulation?

Accepted Answer

They are regulatory DNA sequences located near the promoter that bind specific transcription factors to regulate gene expression.

Question 16

A gene is found to be highly methylated in a certain cell type. Which of the following is the most likely outcome?

Accepted Answer

The gene will be transcriptionally silent due to condensed chromatin.

Question 17

Which of the following best describes the role of repressors in eukaryotic gene regulation?

Accepted Answer

Repressors are regulatory proteins that bind to silencers or other regulatory sequences to decrease transcription.

Question 18

Which of the following equations best represents the relationship between the number of possible proteins ($P$) produced by alternative splicing and the number of exons ($n$) in a gene, assuming each exon can be included or excluded independently (except at least one exon must be included)?

Accepted Answer

$P = 2^n - 1$

Question 19

A scientist uses a restriction endonuclease to cut a plasmid and inserts a gene of interest. Which enzyme is then used to seal the gene into the plasmid, and what type of bond does it form?

Accepted Answer

DNA ligase; it forms phosphodiester bonds.

Gene Expression in Eukaryotes: Regulation and Mechanisms

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