Question 1

Which of the following best describes the primary difference between prokaryotic and eukaryotic genomes?

Accepted Answer

Prokaryotic genomes are small, circular, mostly coding DNA without histones, while eukaryotic genomes are large, linear, mostly noncoding DNA with histones.

Question 2

Which of the following is a direct effect of DNA methylation at CpG islands near gene promoters?

Accepted Answer

It represses transcription by promoting chromatin condensation and silencing gene expression.

Question 3

A mutation prevents the acetylation of histone tails in a eukaryotic cell. What is the most likely consequence?

Accepted Answer

Decreased gene expression due to tighter chromatin packing.

Question 4

Which of the following is an example of a cis-regulatory element?

Accepted Answer

Enhancer DNA sequence

Question 5

What is the role of an enhancer in gene regulation?

Accepted Answer

It increases gene expression by binding activator proteins and looping to the promoter to facilitate RNA polymerase binding.

Question 6

Which process is responsible for generating multiple protein isoforms from a single gene in eukaryotes?

Accepted Answer

Alternative splicing of pre-mRNA

Question 7

A scientist observes that a gene is highly expressed in liver cells but not in brain cells. Which mechanism most likely explains this observation?

Accepted Answer

Liver cells have tissue-specific enhancers and activator proteins that are absent in brain cells.

Question 8

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

Accepted Answer

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

Question 9

Which of the following is most likely associated with actively transcribed genes?

Accepted Answer

Histone acetylation and open chromatin structure

Question 10

A mutation in the gene encoding a ubiquitin ligase results in nonfunctional enzyme. What is a likely cellular consequence?

Accepted Answer

Proteins accumulate due to failure to be tagged for degradation.

Question 11

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

Accepted Answer

They reposition nucleosomes to alter DNA accessibility for transcription factors.

Question 12

Which of the following equations correctly represents the calculation of recombination frequency ($$RF) $$between two genes?

Accepted Answer

$$RF = \frac{	ext{Number of recombinant offspring}}{	ext{Total number of offspring}} 	imes 100$$

Question 13

Which of the following is a trans-regulatory element involved in gene expression?

Accepted Answer

Transcription factor protein

Question 14

In a eukaryotic cell, which event occurs in the nucleus and is essential for mRNA stability and export?

Accepted Answer

Addition of a 5' cap and a poly(A) tail to pre-mRNA

Question 15

Which of the following best describes the function of an insulator in gene regulation?

Accepted Answer

It blocks the interaction between enhancers and promoters when placed between them.

Question 16

A researcher finds that a gene is transcribed at very low levels in brain cells but at high levels in liver cells. Which regulatory mechanism most likely explains this difference?

Accepted Answer

Brain cells have repressor proteins bound to silencers near the gene.

Question 17

Which of the following is a correct sequence of events in the central dogma of molecular biology?

Accepted Answer

DNA $$\rightarrow$$ RNA $$\rightarrow$$ Protein

Question 18

Which of the following best describes the effect of histone acetylation on gene expression?

Accepted Answer

It opens chromatin structure and activates transcription.

Question 19

Which of the following is a post-translational modification that targets proteins for degradation?

Accepted Answer

Ubiquitination

Transcriptional and Post-Transcriptional Regulation of Gene Expression

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