Question 1

Which of the following best describes the function of an operon in prokaryotic gene regulation?

Accepted Answer

A cluster of functionally related genes controlled by a single 'on-off switch' called an operator.

Question 2

In the trp operon, what role does tryptophan play in regulating gene expression?

Accepted Answer

It acts as a corepressor, activating the repressor protein to shut off the operon.

Question 3

Which of the following scenarios would result in the highest level of lac operon transcription in E. coli?

Accepted Answer

Low glucose, high lactose

Question 4

What is the effect of histone acetylation on chromatin structure and gene expression?

Accepted Answer

It opens chromatin structure, promoting transcription initiation.

Question 5

Which of the following is true about DNA methylation?

Accepted Answer

It causes long-term inactivation of genes during cellular differentiation.

Question 6

A mutation in the regulatory gene of the lac operon results in a repressor protein that cannot bind allolactose. What is the most likely outcome?

Accepted Answer

The lac operon will be permanently turned off, even in the presence of lactose.

Question 7

Which of the following best explains the difference between repressible and inducible operons?

Accepted Answer

Repressible operons are turned off by the presence of a corepressor, while inducible operons are turned on by an inducer.

Question 8

Which of the following mechanisms is an example of epigenetic inheritance?

Accepted Answer

Methylation of cytosine bases in DNA that is passed to daughter cells.

Question 9

What is the role of general transcription factors in eukaryotic gene expression?

Accepted Answer

They interact with RNA polymerase II at the promoter to initiate transcription.

Question 10

Which of the following statements about control elements in eukaryotic gene regulation is correct?

Accepted Answer

Distal control elements, or enhancers, can be located thousands of base pairs away from the gene they regulate.

Question 11

A researcher finds that a gene is not expressed in a certain cell type because its promoter region is tightly bound by nucleosomes. Which modification would most likely increase expression of this gene?

Accepted Answer

Acetylation of histone tails

Question 12

Which of the following best describes the function of an activator protein in eukaryotic transcription?

Accepted Answer

It binds to an enhancer and stimulates transcription of a gene.

Question 13

Which of the following is a likely consequence of DNA methylation in the promoter region of a tumor suppressor gene?

Accepted Answer

Decreased expression of the tumor suppressor gene

Question 14

Which of the following is a direct result of positive gene regulation by CRP (cAMP receptor protein) in the lac operon?

Accepted Answer

Increased affinity of RNA polymerase for the promoter

Question 15

Which of the following is NOT a mechanism by which eukaryotic cells regulate gene expression?

Accepted Answer

Feedback inhibition of enzyme activity

Question 16

A mutation causes the lac repressor to be unable to bind the operator. What is the most likely effect on the cell?

Accepted Answer

The lac operon will be constitutively expressed, regardless of lactose presence.

Question 17

Which of the following best explains why identical twins can have different susceptibilities to genetically based diseases?

Accepted Answer

Epigenetic modifications can differ between twins, affecting gene expression.

Question 18

Which of the following is a function of general transcription factors in eukaryotic cells?

Accepted Answer

They help RNA polymerase II bind to the promoter and initiate transcription.

Question 19

Which of the following statements about the lac operon is correct?

Accepted Answer

It is an inducible operon that is usually off.

Question 20

Which of the following would most likely result from a mutation that prevents the acetylation of histone tails?

Accepted Answer

Decreased gene expression due to condensed chromatin

Regulation of Gene Expression (Chapter 18): Study Notes

Study Guide - Practice Questions

Study Guide - Flashcards