Question 1

Which of the following best describes the role of histone acetylation in gene regulation?

Accepted Answer

Histone acetylation neutralizes the positive charge on lysine residues, loosening DNA-histone interactions and promoting an open chromatin conformation that facilitates transcription.

Question 2

A mutation prevents the phosphorylation of the C-terminal domain (CTD) of RNA polymerase II during transcription initiation. Which step of transcription is most directly affected?

Accepted Answer

Promoter escape, because phosphorylation of the CTD is required for RNA polymerase II to transition from initiation to elongation.

Question 3

Which of the following mechanisms can result in long-term gene silencing in eukaryotes?

Accepted Answer

Formation of heterochromatin through DNA methylation and recruitment of methyl-CpG-binding proteins.

Question 4

A researcher uses ChIP-Seq to map the binding sites of a transcription factor. Which of the following steps is NOT part of the ChIP-Seq procedure?

Accepted Answer

Directly sequencing RNA transcripts without isolating DNA-protein complexes.

Question 5

Which of the following statements about CpG islands is correct?

Accepted Answer

CpG islands are typically unmethylated in housekeeping genes, allowing for broad gene expression.

Question 6

A mutation in a gene encoding a chromatin remodeling complex prevents nucleosome sliding. Which process would be most directly impaired?

Accepted Answer

The ability to reposition nucleosomes to expose regulatory DNA elements, thereby affecting transcription initiation.

Question 7

Which of the following best explains how DNA methylation can inhibit gene transcription?

Accepted Answer

Both by directly blocking activator binding and by recruiting proteins that compact chromatin.

Question 8

Which of the following is a unique feature of eukaryotic gene regulation compared to bacterial gene regulation?

Accepted Answer

Regulatory elements (enhancers) can be located far from the core promoter and require DNA looping for interaction.

Question 9

A cell is exposed to a steroid hormone. Which sequence of events leads to the activation of target gene transcription?

Accepted Answer

The hormone enters the cell, binds to its receptor, the receptor dimerizes and enters the nucleus, then binds to a glucocorticoid response element (GRE) to activate transcription.

Question 10

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

Accepted Answer

It prevents the spread of chromatin modifications or blocks the action of an enhancer on a neighboring gene.

Question 11

A gene is found to have a nucleosome-free region (NFR) at its core promoter but is not actively transcribed. What does this observation suggest?

Accepted Answer

The presence of an NFR alone is not sufficient for gene activation; additional regulatory factors are required.

Question 12

Which of the following is a direct effect of histone deacetylase (HDAC) activity?

Accepted Answer

Removal of acetyl groups from histone tails, promoting chromatin compaction and transcriptional repression.

Question 13

Which of the following best describes the role of the CREB protein in gene regulation?

Accepted Answer

CREB binds to cAMP response elements (CREs) and, when phosphorylated, recruits CBP to activate transcription.

Question 14

A mutation prevents the dimerization of a leucine zipper transcription factor. What is the most likely consequence?

Accepted Answer

The transcription factor cannot bind to DNA, reducing or abolishing its regulatory activity.

Question 15

Which of the following is a possible outcome of ATP-dependent chromatin remodeling?

Accepted Answer

Sliding nucleosomes along DNA to expose regulatory elements.

Question 16

Which of the following best explains the concept of combinatorial control in eukaryotic gene regulation?

Accepted Answer

Multiple regulatory proteins and mechanisms act together to control the expression of a single gene.

Question 17

A gene is silenced in a specific tissue due to methylation of its CpG island. Which enzyme is primarily responsible for maintaining this methylation pattern after DNA replication?

Accepted Answer

DNA methyltransferase, which adds methyl groups to hemimethylated DNA following replication.

Question 18

Which of the following events occurs during the elongation phase of eukaryotic transcription?

Accepted Answer

Phosphorylation of DSIF and NELF by P-TEFb, releasing the pause and allowing RNA polymerase II to continue elongation.

Question 19

Which of the following is a function of methyl-CpG-binding proteins in gene regulation?

Accepted Answer

They bind to methylated CpG islands and recruit histone deacetylases, leading to chromatin compaction and gene silencing.

Gene Regulation in Eukaryotes I: General Features of Transcriptional Regulation

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