Question 1

Which of the following best describes a 'chromosome territory' in the interphase nucleus?

Accepted Answer

A discrete region of the nucleus occupied by a specific chromosome.

Question 2

Which of the following is a key difference between gene regulation in prokaryotes and eukaryotes?

Accepted Answer

Eukaryotes regulate gene expression at multiple levels, including chromatin structure, while prokaryotes primarily regulate at the level of transcription.

Question 3

A researcher finds that a gene is not being transcribed in a particular cell type. The promoter region of this gene is heavily methylated. What is the most likely explanation for the lack of transcription?

Accepted Answer

Methylation of the promoter region silences the gene by preventing transcription factor binding.

Question 4

Which enzyme is responsible for adding acetyl groups to histone proteins, and what is the effect of this modification?

Accepted Answer

Histone acetyl transferases (HATs); they increase DNA accessibility for transcription.

Question 5

Which of the following best describes the function of the SWI/SNF chromatin remodeling complex?

Accepted Answer

It repositions nucleosomes to expose DNA for transcription.

Question 6

A mutation in a gene encoding a histone methylase is most likely to affect which aspect of gene regulation?

Accepted Answer

The chemical modification of histones, altering chromatin structure and gene accessibility.

Question 7

Which of the following is an example of post-transcriptional regulation in eukaryotes?

Accepted Answer

Alternative splicing of pre-mRNA.

Question 8

RNA interference (RNAi) can silence gene expression by which of the following mechanisms?

Accepted Answer

Targeted degradation of mRNA and inhibition of translation.

Question 9

Which of the following best explains why eukaryotic gene expression is often cell-type specific?

Accepted Answer

Different cell types express different sets of genes in response to developmental and environmental cues.

Question 10

A scientist is studying a gene that is highly expressed in pancreatic islet cells but not in lymphocytes. Which regulatory mechanism is most likely responsible for this tissue-specific expression?

Accepted Answer

Presence of tissue-specific enhancers and transcription factors in pancreatic islet cells.

Question 11

Which of the following statements about enhancers is correct?

Accepted Answer

Enhancers are DNA elements that can increase transcription from a distance and are bound by specific transcription factors.

Question 12

Which of the following is a direct consequence of histone acetylation?

Accepted Answer

Decreased affinity between DNA and histones, making DNA more accessible for transcription.

Question 13

A gene is found to be silenced in a cancer cell line due to DNA methylation. Which of the following treatments could potentially reactivate this gene?

Accepted Answer

Treatment with a DNA methyltransferase inhibitor.

Question 14

Which of the following best describes the role of the TATA box in eukaryotic transcription?

Accepted Answer

It is a DNA sequence that serves as a binding site for the TATA-binding protein (TBP), facilitating the assembly of the transcription initiation complex.

Question 15

Which of the following equations correctly represents the relationship between gene expression (E), chromatin accessibility (A), and DNA methylation (M), assuming that increased accessibility promotes expression and increased methylation represses it?

Accepted Answer

$$E = k 	imes \frac{A}{M}$$

Question 16

A patient has a mutation that prevents the ubiquitination of p53. What is the most likely cellular consequence?

Accepted Answer

p53 will accumulate in the cell, potentially enhancing the DNA damage response.

Question 17

Which of the following is a function of the RNA-induced silencing complex (RISC) in RNA interference?

Accepted Answer

It binds to target mRNA and mediates its degradation or inhibits its translation.

Question 18

Which of the following scenarios best illustrates the concept of alternative splicing?

Accepted Answer

A single gene produces multiple mRNA variants by including or excluding specific exons, resulting in different protein isoforms.

Question 19

Which of the following best explains why DNA methylation at CpG islands is associated with gene silencing?

Accepted Answer

Methylation recruits proteins that compact chromatin, making DNA less accessible to transcription factors.

Regulation of Gene Expression in Eukaryotes

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