Q: Which equation best represents the composition of a nucleosome in eukaryotic chromatin?

$$\text{Nucleosome} = \text{Histone octamer} + \text{DNA}$$

Question 1

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

Accepted Answer

It loosens DNA association with histone proteins, increasing accessibility for transcription factors and RNA polymerase.

Question 2

A researcher observes that a gene is not being transcribed in a particular cell type, even though the gene is present. Which chromatin state is most likely responsible for this observation?

Accepted Answer

Heterochromatin, which is transcriptionally inactive.

Question 3

Which of the following is a direct consequence of alternative splicing during post-transcriptional regulation?

Accepted Answer

A single gene can produce multiple protein variants by combining exons in different ways.

Question 4

What is the primary function of chromatin remodeling complexes in transcriptional regulation?

Accepted Answer

They shift or restructure nucleosomes to expose promoter and regulatory regions for transcription initiation.

Question 5

Which equation best represents the composition of a nucleosome in eukaryotic chromatin?

Accepted Answer

$$	ext{Nucleosome} = 	ext{Histone octamer} + 	ext{DNA}$$

Question 6

A mutation prevents the binding of transcriptional activators to enhancer regions of a gene. What is the most likely outcome?

Accepted Answer

Transcription of the gene will decrease or not occur.

Question 7

Which of the following best explains how cells ensure that related genes are turned on at the same time?

Accepted Answer

By having specific combinations of transcriptional activators that bind to regulatory elements of related genes.

Question 8

During transcription initiation in eukaryotes, which sequence of events is correct?

Accepted Answer

Transcription factors bind to regulatory regions, chromatin is remodeled, and RNA polymerase is recruited to the promoter.

Question 9

Which of the following is NOT a level at which gene expression is regulated in eukaryotes?

Accepted Answer

Genomic regulation by ribosomes

Question 10

A scientist wants to increase the transcription rate of a gene. Which modification would most likely achieve this?

Accepted Answer

Increasing histone acetylation near the gene's promoter.

Question 11

Which of the following statements about euchromatin and heterochromatin is correct?

Accepted Answer

Euchromatin is transcriptionally active and appears lighter under a microscope.

Question 12

Which process allows a single gene to produce multiple protein isoforms in eukaryotes?

Accepted Answer

Alternative splicing

Question 13

What is the role of general (basal) transcription factors in eukaryotic transcription?

Accepted Answer

They bind to the promoter to allow RNA polymerase to load and initiate transcription.

Question 14

Which of the following best describes the effect of chromatin remodeling on gene expression?

Accepted Answer

It moves nucleosomes to expose promoter regions, facilitating transcription initiation.

Question 15

If a cell needs to rapidly increase the expression of a gene, which combination of events is most likely to occur?

Accepted Answer

Histone acetylation increases, chromatin remodeling exposes the promoter, and transcriptional activators bind regulatory elements.

Question 16

Which of the following equations correctly represents the number of DNA bases wrapped around a histone octamer in a nucleosome?

Accepted Answer

$$\sim 200$$ bases

Question 17

Which of the following is a function of regulatory transcription factors?

Accepted Answer

They bind to silencer or enhancer regions to activate or repress transcription.

Question 18

A mutation in the gene encoding a chromatin remodeling complex results in failure to expose the promoter region of a gene. What is the most likely effect?

Accepted Answer

Transcription of the gene will be reduced or absent.

Question 19

Which of the following best explains why different cell types (e.g., liver vs. lens cells) express different genes?

Accepted Answer

Specific combinations of transcriptional activators are present in each cell type, determining which genes are transcribed.

Gene Expression: Transcriptional and Post-Transcriptional Regulation in Eukaryotes

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