Question 1

Which of the following best describes the role of chromosomal territories within the nucleus?

Accepted Answer

They organize chromosomes into distinct regions, providing preferential access to transcriptional and splicing machinery.

Question 2

Transcriptional activity is strongly correlated with chromatin structure. Which of the following statements is most accurate?

Accepted Answer

Euchromatin has a more open structure, allowing easier access for transcriptional machinery to genes.

Question 3

Which of the following is a key difference between constitutive and facultative heterochromatin?

Accepted Answer

Constitutive heterochromatin is permanently compacted and transcriptionally inactive, while facultative heterochromatin can switch between active and inactive states.

Question 4

Which process is most likely to increase the accessibility of transcription factors (TFs) to DNA?

Accepted Answer

Chromatin remodeling that converts heterochromatin to euchromatin.

Question 5

A researcher treats cells with DNase I and observes that certain regions of DNA are rapidly digested, while others are resistant. What does this suggest about the chromatin structure of these regions?

Accepted Answer

DNase I-sensitive regions are likely euchromatin, while resistant regions are likely heterochromatin.

Question 6

Which of the following mechanisms is NOT a level at which gene expression can be controlled in eukaryotes?

Accepted Answer

DNA replication control

Question 7

If a mutation causes the loss of histone acetyltransferase activity, what is the most likely effect on gene expression?

Accepted Answer

Decreased gene expression due to more compact chromatin.

Question 8

Which formula best represents the relationship between nucleosome spacing and transcriptional activity?

Accepted Answer

$$Transcriptional\ Activity \propto \frac{1}{Nucleosome\ Density}$$

Question 9

During which phase of the cell cycle is DNA most accessible for transcription?

Accepted Answer

G1 phase

Question 10

A patient is found to have abnormal DNA methylation patterns in promoter regions of several genes. What is the most likely consequence?

Accepted Answer

Decreased transcription due to silencing of gene expression.

Question 11

Which of the following best explains why euchromatin is more sensitive to DNase I digestion than heterochromatin?

Accepted Answer

Euchromatin has a less compact structure, making DNA more accessible to enzymes.

Question 12

Which of the following is a real-world example of epigenetic regulation affecting phenotype?

Accepted Answer

X-chromosome inactivation in female mammals due to DNA methylation and histone modification.

Question 13

Which of the following statements about chromatin remodeling is correct?

Accepted Answer

Chromatin remodeling can alter gene expression by changing the accessibility of DNA to transcription factors.

Question 14

A scientist observes that a gene is highly expressed in liver cells but not in skin cells, despite both cell types having the same DNA sequence. Which concept best explains this observation?

Accepted Answer

Epigenetic regulation and chromatin remodeling

Question 15

Which of the following is most likely to occur if a region of DNA transitions from euchromatin to heterochromatin?

Accepted Answer

Decreased transcription due to reduced accessibility.

Question 16

Which of the following best describes the effect of nucleosome spacing on gene expression?

Accepted Answer

Tightly packed nucleosomes generally repress gene expression.

Question 17

Which equation best represents the effect of DNA methylation on gene expression?

Accepted Answer

$$Gene\ Expression \propto \frac{1}{DNA\ Methylation}$$

Question 18

Which of the following is NOT a mechanism by which chromatin structure can be altered?

Accepted Answer

DNA polymerase activity

Question 19

A cell is observed to have increased levels of histone acetylation. What is the most likely effect on chromatin structure and gene expression?

Accepted Answer

Chromatin becomes more open and gene expression increases.

Chromatin Remodelling & Epigenetics: Mechanisms of Gene Expression Regulation

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