Question 1

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

Accepted Answer

Eukaryotic DNA is packaged into chromatin, requiring additional mechanisms for DNA accessibility and regulation at multiple levels.

Question 2

Which of the following histone modifications is most commonly associated with increased transcriptional activity?

Accepted Answer

Histone acetylation of lysine residues by histone acetyltransferases (HATs)

Question 3

A mutation eliminates the TATA box from a gene's core promoter. Which of the following is the most likely consequence?

Accepted Answer

Transcription initiation will be impaired because TFIID cannot bind efficiently.

Question 4

Which of the following best describes the function of the SWI/SNF chromatin remodeling complex?

Accepted Answer

It uses ATP to reposition or remove nucleosomes, increasing DNA accessibility.

Question 5

In the yeast GAL gene system, what is the role of GAL80 in the absence of galactose?

Accepted Answer

GAL80 binds to GAL4 and masks its activation domain, preventing transcription.

Question 6

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

Accepted Answer

DNA methylation occurs primarily at CpG sites and is associated with transcriptional repression.

Question 7

A gene contains both enhancer and silencer elements. Which of the following best describes how these elements function?

Accepted Answer

Enhancers increase transcription by binding activators, while silencers decrease transcription by binding repressors.

Question 8

Which of the following is a key difference between general and specific transcription factors in eukaryotes?

Accepted Answer

General transcription factors are required for basal transcription at all Pol II promoters, while specific transcription factors regulate transcription in response to signals.

Question 9

Which of the following best explains how DNA methylation and histone deacetylation can cooperate to repress gene expression?

Accepted Answer

DNA methylation recruits methyl-CpG-binding proteins, which in turn recruit histone deacetylases (HDACs) to remove acetyl groups from histones, leading to chromatin condensation and transcriptional repression.

Question 10

A researcher inserts an upstream activating sequence (UAS) from the yeast GAL system upstream of a heterologous promoter in yeast. What is the most likely outcome?

Accepted Answer

The UAS can activate transcription from the heterologous promoter in a position- and orientation-independent manner, provided GAL4 is present.

Question 11

Which of the following best describes the function of the Mediator complex in eukaryotic transcription?

Accepted Answer

Mediator acts as a coactivator, connecting DNA-bound activators to the RNA polymerase II machinery and helping assemble the transcription initiation complex.

Question 12

Which of the following is a characteristic of focused promoters in eukaryotes?

Accepted Answer

They direct transcription initiation at a single major site or within a narrow region.

Question 13

A mutation in the GAL3 gene of yeast results in the inability to induce GAL gene expression in the presence of galactose. Which of the following best explains this phenotype?

Accepted Answer

GAL3 is required to relieve GAL80 inhibition of GAL4 in the presence of galactose.

Question 14

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

Accepted Answer

Histone acetylation reduces the positive charge on histones, loosening DNA-histone interactions and promoting transcription.

Question 15

Which of the following is true regarding the modular structure of eukaryotic transcription factors?

Accepted Answer

The DNA-binding domain recognizes specific DNA sequences, while the activation domain interacts with cofactors and the transcription machinery.

Question 16

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

Accepted Answer

It blocks the interaction between an enhancer and a non-target promoter, restricting enhancer activity to specific genes.

Question 17

Which of the following is a direct consequence of nucleosome repositioning by chromatin remodeling complexes?

Accepted Answer

Altered accessibility of regulatory DNA sequences to transcription factors

Question 18

Which of the following best explains how combinatorial control of transcription is achieved in eukaryotes?

Accepted Answer

Multiple transcription factors bind to different regulatory elements, and their combined effects determine the level of gene expression.

Transcriptional Regulation in Eukaryotes: Mechanisms and Model Systems

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