Q: Which equation best represents the condensation of DNA by nucleosome formation?

$$\text{Condensation factor} = \frac{\text{Length of naked DNA}}{\text{Length of DNA in nucleosome}} \approx 7$$

Question 1

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

Accepted Answer

It unpacks chromatin to the 10 nm level, making specific genes accessible for transcription.

Question 2

A nucleosome consists of which of the following components?

Accepted Answer

A histone core octamer (2 each of H2A, H2B, H3, H4) and about 1.65 turns of DNA (~150 bp) wrapped around it.

Question 3

Which histone protein is NOT part of the nucleosome core but is involved in chromatin condensation?

Accepted Answer

H1

Question 4

DNA methylation typically occurs at CpG sites and is catalyzed by DNA methyl transferases. What is the effect of DNA methylation on gene expression?

Accepted Answer

It causes chromatin to condense, blocking transcription of specific genes.

Question 5

Which of the following is an example of epigenetic inheritance?

Accepted Answer

Inheritance of chromatin modification patterns, such as methylation and acetylation, that affect gene expression.

Question 6

Which equation best represents the condensation of DNA by nucleosome formation?

Accepted Answer

$$	ext{Condensation factor} = \frac{	ext{Length of naked DNA}}{	ext{Length of DNA in nucleosome}} \approx 7$$

Question 7

Which of the following statements about promoter-proximal elements is correct?

Accepted Answer

They are DNA binding sites for regulatory transcription factors located within about 250 bp upstream of the transcription start site.

Question 8

Enhancers and silencers are regulatory sequences that can be located far from the core promoter. Which property distinguishes them from promoter-proximal elements?

Accepted Answer

They are orientation independent and can function upstream, downstream, or within the gene.

Question 9

A cell receives a signal to differentiate into a muscle cell. Which process is most directly responsible for activating muscle-specific gene expression?

Accepted Answer

Production of muscle-specific transcription factor proteins that activate transcription of muscle genes.

Question 10

Which of the following best explains why actively transcribed genes are more susceptible to DNase I digestion?

Accepted Answer

Actively transcribed genes are located in decondensed chromatin, making their DNA more accessible to DNase I.

Question 11

Which of the following is a direct result of histone acetylation?

Accepted Answer

Chromatin becomes more decondensed, increasing transcription.

Question 12

Which equation best represents the relationship between mRNA stability and protein production?

Accepted Answer

$$	ext{Protein production} \propto 	ext{mRNA stability}$$

Question 13

Alternative splicing allows a single gene to produce multiple protein products. Which scenario best illustrates this process?

Accepted Answer

A gene is transcribed into multiple mRNAs, each containing different combinations of exons.

Question 14

Which of the following is a mechanism of post-transcriptional control in eukaryotes?

Accepted Answer

Alternative splicing of primary transcripts.

Question 15

RNA interference (RNAi) involves the action of miRNAs. Which step is essential for miRNA-mediated gene silencing?

Accepted Answer

miRNA binds to complementary mRNA sequences, leading to mRNA degradation or inhibition of translation.

Question 16

Which of the following best describes the function of the mediator complex in transcription initiation?

Accepted Answer

It facilitates contact between activators bound to enhancers and RNA polymerase II at the core promoter.

Question 17

A mutation in a gene encoding a regulatory transcription factor results in the loss of its DNA-binding domain. What is the most likely consequence?

Accepted Answer

The transcription factor will not be able to bind to its target DNA sequence, leading to reduced or absent gene expression.

Question 18

Which of the following equations best represents the effect of histone acetylation on transcription rate?

Accepted Answer

$$	ext{Transcription rate} \propto 	ext{Histone acetylation}$$

Question 19

Which scenario best illustrates the concept of differential gene expression in eukaryotes?

Accepted Answer

Different cell types express different sets of genes, resulting in specialized functions.

Control of Gene Expression in Eukaryotes

Study Guide - Practice Questions

Study Guide - Flashcards