Question 1

Which of the following best describes the role of chromatin remodeling in eukaryotic gene regulation?

Accepted Answer

It uses ATP to reposition, remove, or replace nucleosomes, thereby altering DNA accessibility for transcription.

Question 2

What is the effect of acetylation on histone tails, and how does this impact gene expression?

Accepted Answer

Acetylation neutralizes some positive charges on histone tails, loosening DNA binding and promoting gene expression.

Question 3

A gene is found to be silenced in a specific tissue due to DNA methylation. Which of the following mechanisms is most likely responsible for this silencing?

Accepted Answer

Methylation of CpG islands near the promoter prevents activator binding and recruits proteins that condense chromatin.

Question 4

Which of the following statements about CpG islands is correct?

Accepted Answer

CpG islands are typically unmethylated in housekeeping genes, allowing for their constant expression.

Question 5

During transcriptional activation, which of the following events is most likely to occur at the promoter region of an active gene?

Accepted Answer

A nucleosome-free region (NFR) forms at the core promoter, flanked by well-positioned nucleosomes (-1 and +1).

Question 6

Which of the following best explains how epigenetic changes can be inherited through cell division?

Accepted Answer

DNA methylation patterns are maintained by maintenance methyltransferases after DNA replication.

Question 7

A mutation causes a loss of function in a gene encoding a histone acetyltransferase. What is the most likely consequence for gene expression in the affected cells?

Accepted Answer

Decreased acetylation of histones and reduced gene expression.

Question 8

Which of the following is a direct result of alternative splicing in eukaryotic cells?

Accepted Answer

Production of multiple protein isoforms from a single gene.

Question 9

Which of the following best describes the function of regulatory transcription factors?

Accepted Answer

They modulate the rate of transcription by binding to enhancers or silencers near the promoter.

Question 10

A researcher finds that a gene is highly expressed in liver cells but not in muscle cells. Which mechanism is most likely responsible for this tissue-specific expression?

Accepted Answer

The gene's CpG island is unmethylated in liver cells and methylated in muscle cells.

Question 11

Which of the following is a characteristic of enhancers in eukaryotic gene regulation?

Accepted Answer

They are DNA elements that can function at variable distances and orientations relative to the promoter.

Question 12

Which of the following best describes the process of RNA interference (RNAi)?

Accepted Answer

RNAi involves the binding of small noncoding RNAs to mRNAs, leading to their degradation or inhibition of translation.

Question 13

Which of the following posttranslational modifications targets a protein for degradation?

Accepted Answer

Ubiquitination

Question 14

A gene is found to have a nucleosome-free region (NFR) at its core promoter. What is the most likely consequence for this gene?

Accepted Answer

It is likely to be actively transcribed.

Question 15

Which of the following statements about epigenetics is correct?

Accepted Answer

Epigenetic changes involve modifications that do not alter the DNA sequence but can be inherited.

Question 16

Which of the following is most likely to occur if the poly-A tail of an mRNA is rapidly shortened?

Accepted Answer

The mRNA will be rapidly degraded due to loss of polyA-binding protein protection.

Question 17

Which of the following best explains the difference in development between queen and worker honeybees, as shown in the provided image?

Accepted Answer

Queens are fed royal jelly, which induces epigenetic changes that alter gene expression.

Question 18

Which of the following is a function of the Mediator complex in eukaryotic transcription?

Accepted Answer

It mediates interactions between regulatory transcription factors and RNA polymerase II.

Question 19

Which of the following is true regarding the inheritance of DNA methylation patterns?

Accepted Answer

Maintenance methylation ensures that methylation patterns are copied to daughter strands during DNA replication.

Question 20

Which of the following best describes the role of RNA-binding proteins (RBPs) in alternative splicing?

Accepted Answer

RBPs bind to specific RNA sequences to promote or inhibit the use of particular splice sites, resulting in tissue-specific protein isoforms.

Eukaryotic Gene Regulation and Epigenetic Mechanisms

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