Question 1

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

Accepted Answer

It brings enhancers into close physical proximity to promoters, facilitating transcription activation.

Question 2

Which protein is commonly associated with insulator sequences and is crucial for establishing topologically associated domains (TADs)?

Accepted Answer

CTCF

Question 3

A mutation in a limb-specific enhancer of the Sonic Hedgehog (Shh) gene leads to polydactyly (extra digits) in humans. What does this example illustrate about enhancer function?

Accepted Answer

Enhancers can regulate gene expression in a tissue-specific manner, and mutations can cause developmental disorders.

Question 4

Which of the following is NOT a major type of epigenetic modification discussed in the lecture?

Accepted Answer

RNA splicing

Question 5

Which histone modification is most commonly associated with transcriptionally active euchromatin?

Accepted Answer

$$\mathrm{H3K4me3}$$

Question 6

What is the effect of histone acetylation on chromatin structure and gene expression?

Accepted Answer

It decreases the positive charge of histones, loosening chromatin and promoting transcription.

Question 7

Which of the following statements about DNA methylation in mammals is TRUE?

Accepted Answer

It typically occurs at CpG dinucleotides and is associated with transcriptional repression.

Question 8

A gene is found to be silenced in a differentiated cell due to DNA methylation at its promoter. Which enzyme is most directly responsible for maintaining this methylation pattern during DNA replication?

Accepted Answer

DNA methyltransferase (DNMT1)

Question 9

Which of the following best describes the difference between constitutive and facultative heterochromatin?

Accepted Answer

Constitutive heterochromatin is always condensed and transcriptionally silent, while facultative heterochromatin can change structure and activity depending on cell type or developmental stage.

Question 10

Which of the following is a direct consequence of nucleosome positioning over a gene promoter?

Accepted Answer

Reduced accessibility of transcription factors, leading to decreased transcription.

Question 11

Which of the following best explains how DNA methylation can lead to transcriptional repression?

Accepted Answer

Methylated DNA recruits proteins that bind methylated CpGs and recruit histone deacetylases (HDACs), leading to chromatin condensation.

Question 12

Which of the following is TRUE regarding genomic imprinting?

Accepted Answer

It involves parent-of-origin-specific DNA methylation that regulates gene expression.

Question 13

Which of the following is a function of chromatin remodeling complexes?

Accepted Answer

They reposition or evict nucleosomes to alter DNA accessibility.

Question 14

Which of the following histone modifications is most commonly associated with constitutive heterochromatin?

Accepted Answer

$$\mathrm{H3K9me3}$$

Question 15

A ChIP-seq experiment identifies a region of the genome with high levels of $$\mathrm{H3K27ac}. $$What does this suggest about the region?

Accepted Answer

It is likely an active enhancer.

Question 16

Which of the following best describes the function of insulator sequences?

Accepted Answer

They prevent enhancers from activating the wrong promoters by blocking interactions between chromatin domains.

Question 17

Which of the following is a plausible outcome if a mutation disrupts the methylation pattern at the IGF2/H19 locus?

Accepted Answer

Impaired genomic imprinting, potentially leading to abnormal growth or disease.

Question 18

Which of the following statements about chromatin readers is correct?

Accepted Answer

They are proteins that bind specific histone modifications and help recruit other factors to modify chromatin structure.

Question 19

Which of the following is a direct effect of histone methylation?

Accepted Answer

It can either increase or decrease nucleosome-DNA interaction depending on the site and type of methylation.

Question 20

Which of the following best explains why promoters or enhancers located within nucleosomes are generally less accessible to transcription?

Accepted Answer

Nucleosomes physically block access of transcription factors to DNA.

Regulation of Eukaryotic Transcription: Epigenetic Modifications and Chromatin Structure

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