Question 1

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

Accepted Answer

They add acetyl groups to histones, resulting in a more open chromatin structure and increased transcription.

Question 2

A mutation causes a repressor protein to lose its ability to bind to the operator region of a gene. What is the most likely consequence?

Accepted Answer

Transcription of the gene will increase because the repressor can no longer inhibit RNA polymerase binding.

Question 3

Which of the following is a direct effect of DNA methylation at promoter regions?

Accepted Answer

Recruitment of methyl DNA-binding proteins that promote chromatin condensation and transcriptional repression.

Question 4

During post-transcriptional control, which process allows a single gene to produce multiple protein isoforms?

Accepted Answer

Alternative splicing of pre-mRNA.

Question 5

A scientist observes that a certain mRNA is rapidly degraded in the cytoplasm, resulting in low protein levels. Which regulatory mechanism is most likely responsible?

Accepted Answer

Post-transcriptional control by microRNA (miRNA) mediated RNA interference.

Question 6

Which of the following best explains why chromatin remodeling is necessary for transcription to occur?

Accepted Answer

Chromatin remodeling exposes DNA regulatory sequences by shifting nucleosomes, allowing transcription factors and RNA polymerase to access the DNA.

Question 7

A patient has a genetic disorder in which their cells cannot add ubiquitin to proteins. Which cellular process would be most directly affected?

Accepted Answer

Degradation of misfolded or damaged proteins by the proteasome.

Question 8

Which of the following sequences is most likely to be found near the transcription start site and is essential for the binding of general transcription factors?

Accepted Answer

TATA box

Question 9

In the context of the central dogma, which of the following correctly represents the flow of genetic information?

Accepted Answer

$$ DNA \rightarrow RNA \rightarrow Protein $$

Question 10

A mutation in the promoter-proximal element of a gene reduces the binding affinity of an activator protein. What is the most likely effect on gene expression?

Accepted Answer

Decreased transcription because the activator cannot efficiently recruit the transcriptional machinery.

Question 11

Which of the following best describes the function of a pioneer transcription factor?

Accepted Answer

It binds to DNA associated with nucleosomes and helps decondense chromatin, making genes accessible for transcription.

Question 12

A researcher treats cells with a drug that inhibits histone deacetylases (HDACs). What is the expected effect on gene expression?

Accepted Answer

Increased gene expression due to more open chromatin structure.

Question 13

Which of the following is an example of post-translational modification that can regulate protein activity?

Accepted Answer

Phosphorylation by kinases, using the reaction $$ ATP \rightarrow ADP $$

Question 14

A point mutation changes a codon from $$ UAU  ($$tyrosine) to $$ UAA  ($$stop codon). What type of mutation is this, and what is its likely effect?

Accepted Answer

Nonsense mutation; results in premature termination of translation.

Question 15

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

Accepted Answer

They bind to complementary mRNA sequences and promote mRNA degradation or inhibit translation.

Question 16

A gene is transcribed but not translated into protein. Which regulatory mechanism is most likely responsible?

Accepted Answer

Translational control, such as inhibition of ribosome binding to mRNA.

Question 17

Which of the following scenarios best illustrates the effect of a frameshift mutation?

Accepted Answer

Insertion of a single nucleotide in the coding region, altering all downstream codons.

Question 18

Which of the following is a function of general transcription factors?

Accepted Answer

They bind to the core promoter and help RNA polymerase initiate transcription.

Question 19

A cell is exposed to a signal that activates a kinase, which then phosphorylates a target protein. What is the most likely immediate effect of this modification?

Accepted Answer

The activity of the target protein is altered, either activating or inhibiting its function.

Question 20

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

Accepted Answer

They are distant DNA elements that bind regulatory transcription factors to increase the rate of transcription.

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

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