Question 1

Which of the following best describes the role of attenuation in the regulation of the trp operon in *E. coli*?

Accepted Answer

Attenuation causes premature termination of transcription based on tryptophan availability.

Question 2

A mutation in the leader region of the trp operon removes both tryptophan codons. What is the most likely effect on gene expression?

Accepted Answer

Attenuation will not occur, leading to increased expression of trp structural genes even when tryptophan is abundant.

Question 3

Which of the following is a key difference between gene regulation in prokaryotes and eukaryotes?

Accepted Answer

Eukaryotes often regulate gene expression at multiple levels, including chromatin modification and mRNA processing.

Question 4

Which enzyme is responsible for adding acetyl groups to histone proteins, and what is the effect of this modification?

Accepted Answer

Histone acetyltransferase (HAT); increases gene expression

Question 5

A plant biologist wants to create an Arabidopsis mutant that flowers earlier than wild type. Which genetic strategy would most likely achieve this?

Accepted Answer

Overexpress the FLD gene to reduce FLC expression.

Question 6

Which of the following statements about the nucleosome is correct?

Accepted Answer

It consists of a DNA molecule wrapped around an octamer of histone proteins.

Question 7

What is the primary function of the TATA-binding protein (TBP) in eukaryotic transcription?

Accepted Answer

It determines the transcription start site by binding to the TATA box.

Question 8

Which of the following best explains why attenuation does not occur in eukaryotes?

Accepted Answer

Transcription and translation are separated in time and space in eukaryotes.

Question 9

A researcher observes increased acetylation of histone H4 at lysine 27 in a region of euchromatin. What is the most likely consequence?

Accepted Answer

Increased gene expression in that region

Question 10

Which of the following is NOT a function of the C-terminal domain (CTD) of RNA polymerase II?

Accepted Answer

Recruitment of ribosomes for translation

Question 11

Which of the following best describes the effect of histone deacetylase (HDAC) inhibitors in cancer therapy?

Accepted Answer

They increase histone acetylation, potentially activating tumor suppressor genes.

Question 12

Which of the following is a correct statement about the regulation of alternative splicing in eukaryotes?

Accepted Answer

It determines which RNA splice forms of a gene are translated.

Question 13

Which of the following is true regarding the effect of methylation on histones?

Accepted Answer

Methylation of arginine and lysine residues can correlate with increased gene activity.

Question 14

Which of the following is a direct result of phosphorylation of the carboxyl-terminal domain (CTD) of RNA polymerase II?

Accepted Answer

Release of RNA polymerase II from the promoter to begin transcription

Question 15

Which of the following is a characteristic of eukaryotic gene regulation but NOT prokaryotic gene regulation?

Accepted Answer

Regulation by chromatin structure

Question 16

Which of the following best describes the function of general transcription factors (GTFs) in eukaryotic transcription?

Accepted Answer

They are required for all RNA polymerase II-mediated transcription.

Question 17

Which of the following is a plausible outcome if a fly mutant contains histones resistant to acetylation?

Accepted Answer

The mutant will show decreased levels of gene expression.

Question 18

Which of the following is a correct pairing of a regulatory protein and its DNA element?

Accepted Answer

Transcription factor; enhancer

Question 19

Which of the following is true regarding the effect of chromatin structure on gene expression?

Accepted Answer

Compact chromatin (heterochromatin) inhibits transcription.

Question 20

Which of the following is a correct statement about the organization of eukaryotic genes?

Accepted Answer

Each structural gene has its own promoter and is transcribed separately (monocistronic).

Gene Regulation in Prokaryotes and Eukaryotes: Mechanisms and Molecular Basis

Study Guide - Practice Questions