Question 1

Which of the following best describes the role of histone acetyl transferases (HATs) in gene expression regulation?

Accepted Answer

HATs add acetyl groups to histones, promoting chromatin decondensation and increased transcription.

Question 2

A mutation causes the loss of function of a chromatin remodeling complex. What is the most likely consequence for gene expression?

Accepted Answer

Chromatin will remain condensed, preventing access to DNA and reducing gene expression.

Question 3

Which equation best represents the Central Dogma of molecular biology?

Accepted Answer

$DNA \rightarrow RNA \rightarrow Protein$

Question 4

A researcher observes that a gene is highly expressed only when its promoter region is decondensed. Which modification is most likely responsible for this decondensation?

Accepted Answer

Addition of acetyl groups to histones by HATs.

Question 5

Which of the following is a post-transcriptional mechanism for regulating gene expression?

Accepted Answer

Splicing of pre-mRNA to produce different mature mRNAs.

Question 6

A cell is exposed to a drug that increases DNA methylation at promoter regions. What is the expected effect on gene expression?

Accepted Answer

Gene expression will decrease due to chromatin condensation.

Question 7

Which of the following best explains how microRNAs (miRNAs) regulate gene expression?

Accepted Answer

miRNAs bind to complementary mRNA sequences, leading to mRNA degradation or translation inhibition.

Question 8

Which of the following scenarios illustrates translational control of gene expression?

Accepted Answer

A ribosome pauses or fails to initiate translation on an mRNA, reducing protein production.

Question 9

A mutation in the promoter-proximal element of a gene prevents activator protein binding. What is the most likely outcome?

Accepted Answer

Transcription of the gene will decrease.

Question 10

Which of the following is a consequence of a point mutation that creates a premature stop codon in a coding sequence?

Accepted Answer

The protein will be truncated and likely nonfunctional.

Question 11

Which process is directly affected by the activity of general transcription factors?

Accepted Answer

Initiation of transcription by RNA polymerase.

Question 12

A scientist discovers a protein that binds to enhancer sequences far from the core promoter and increases transcription. This protein is best classified as:

Accepted Answer

An activator.

Question 13

Which of the following changes would most likely increase the stability and lifespan of an mRNA molecule in the cytoplasm?

Accepted Answer

Addition of a poly-A tail.

Question 14

Which equation represents the conversion of ATP to ADP during protein phosphorylation?

Accepted Answer

$ATP \rightarrow ADP + P_i$

Question 15

A gene is silenced in a cell due to methylation of its promoter region. Which enzyme is most likely responsible for this modification?

Accepted Answer

DNA methyltransferase

Question 16

Which of the following is an example of post-translational control of gene expression?

Accepted Answer

Phosphorylation of a protein to activate or deactivate its function.

Question 17

A mutation causes the inversion of a DNA segment within a gene. What is the most likely effect on the gene product?

Accepted Answer

The gene product may be nonfunctional due to altered amino acid sequence.

Question 18

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

Accepted Answer

RISC binds to mRNA and cleaves it, preventing translation.

Question 19

Which of the following is a direct result of chromatin decondensation?

Accepted Answer

Increased transcription of genes in the decondensed region.

Question 20

A cell has a mutation that prevents the removal of introns from pre-mRNA. What is the most likely consequence?

Accepted Answer

The mature mRNA will contain introns, possibly resulting in a nonfunctional protein.

Gene Expression Control: Transcriptional, Translational, and Post-Translational Regulation

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