Q: Which equation best represents the steady-state level of mRNA in a cell?

$$\text{Steady-state mRNA} = \text{Rate of transcription} - \text{Rate of degradation}$$

Question 1

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

Accepted Answer

Histone acetylation neutralizes the positive charge on lysine residues, loosening chromatin and increasing transcription.

Question 2

A mutation causes the loss of function of histone deacetylase (HDAC) enzymes in a cell. What is the most likely consequence for gene expression?

Accepted Answer

Gene expression will increase due to persistent acetylation and open chromatin structure.

Question 3

Which chromatin remodeling mechanism is illustrated when a chromatin remodeler uses ATP to slide nucleosomes along DNA, exposing previously hidden DNA regions?

Accepted Answer

Alteration of DNA-protein contacts

Question 4

DNA methylation most commonly occurs at which nucleotide sequence, and what is its typical effect on gene expression?

Accepted Answer

At CpG islands, leading to decreased gene expression

Question 5

Which of the following is a cis-acting element that can increase transcription rates and may be located far from the gene it regulates?

Accepted Answer

Enhancer

Question 6

A gene's promoter contains a TATA box, CAAT box, and GC box. Mutational analysis shows that mutation in the TATA box drastically reduces transcription, while mutation in the GC box has a moderate effect. What does this suggest about the function of these promoter elements?

Accepted Answer

The TATA box is essential for basal transcription initiation, while the GC box enhances transcription levels.

Question 7

Which functional domain of a transcription factor is responsible for binding to specific DNA sequences?

Accepted Answer

DNA-binding domain

Question 8

What is the role of the SWI/SNF chromatin remodeling complex in gene regulation?

Accepted Answer

It repositions nucleosomes to make DNA accessible to transcription factors.

Question 9

Which of the following best describes alternative mRNA splicing?

Accepted Answer

It generates different protein isoforms from a single gene by varying the combination of exons included in the mature mRNA.

Question 10

A cell is treated with 5-azacytidine, a base analog that cannot be methylated. What is the expected effect on gene expression?

Accepted Answer

Gene expression will increase due to reduced methylation and derepression of normally silent genes.

Question 11

Which of the following mechanisms is responsible for rapid degradation of mRNA containing a premature stop codon?

Accepted Answer

Nonsense-mediated decay

Question 12

Which equation best represents the steady-state level of mRNA in a cell?

Accepted Answer

$$	ext{Steady-state mRNA} = 	ext{Rate of transcription} - 	ext{Rate of degradation}$$

Question 13

Which posttranslational modification is most likely to alter the function of a protein by adding a phosphate group to serine residues?

Accepted Answer

Phosphorylation

Question 14

What is the primary function of proteasomes in posttranscriptional gene regulation?

Accepted Answer

They degrade proteins that have been tagged with ubiquitin.

Question 15

Which of the following statements about RNA interference (RNAi) is correct?

Accepted Answer

RNAi uses short double-stranded RNA molecules to repress translation and trigger mRNA degradation.

Question 16

A scientist wants to reduce the expression of a dominant mutant gene product without affecting the normal allele. Which strategy is most appropriate?

Accepted Answer

Use RNA interference to specifically degrade the mutant mRNA.

Question 17

Which of the following is NOT a way that chromatin remodeling complexes alter nucleosome structure?

Accepted Answer

Degrading mRNA to regulate protein levels

Question 18

Which of the following best explains why eukaryotic gene regulation is more complex than prokaryotic gene regulation?

Accepted Answer

Eukaryotes have spatial separation of transcription and translation, mRNA processing, and cellular differentiation.

Question 19

Which of the following is a plausible outcome of heavy methylation of CpG islands in a gene's promoter region?

Accepted Answer

The gene is less likely to be transcribed due to recruitment of repressive chromatin remodeling complexes.

Regulation of Gene Expression in Eukaryotes

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