$$\text{Lactose} + \text{H}_2\text{O} \rightarrow \text{Glucose} + \text{Galactose}$$

Question 1

Which of the following best describes the function of the operator in a prokaryotic operon?

Accepted Answer

It is a DNA sequence where a repressor protein can bind to regulate transcription.

Question 2

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

Accepted Answer

Tryptophan acts as a corepressor, activating the repressor to inhibit transcription.

Question 3

Which equation represents the hydrolysis of lactose by β-galactosidase?

Accepted Answer

$$	ext{Lactose} + 	ext{H}_2	ext{O} ightarrow 	ext{Glucose} + 	ext{Galactose}$$

Question 4

Which of the following scenarios would result in maximal transcription of the lac operon?

Accepted Answer

Glucose absent, lactose present

Question 5

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

Accepted Answer

Acetylation opens chromatin and increases transcription.

Question 6

Which of the following is TRUE regarding DNA methylation?

Accepted Answer

DNA methylation occurs on cytosine residues and decreases gene expression.

Question 7

Which of the following best explains why all cells in an organism contain the same DNA but express different genes?

Accepted Answer

Differential gene expression allows cells to specialize by turning off certain genes.

Question 8

Which of the following statements about epigenetic inheritance is correct?

Accepted Answer

Epigenetic inheritance involves heritable changes in gene expression without altering the DNA sequence.

Question 9

Which of the following is a function of microRNAs (miRNAs) in eukaryotic cells?

Accepted Answer

miRNAs bind to mRNA and inhibit translation or promote degradation.

Question 10

Which of the following mutations would most likely convert a proto-oncogene into an oncogene?

Accepted Answer

A mutation that greatly increases the amount of the proto-oncogene protein.

Question 11

Which of the following statements correctly describes a characteristic of tumor-suppressor genes?

Accepted Answer

They encode proteins that help prevent uncontrolled cell growth.

Question 12

Which of the following is NOT a component of the lac operon?

Accepted Answer

Regulatory gene

Question 13

Which protein acts as an activator for the lac operon when glucose is absent?

Accepted Answer

CRP (cAMP receptor protein)

Question 14

Which equation describes the relationship between cAMP concentration and glucose availability in E. coli?

Accepted Answer

$$	ext{[cAMP]} \propto \frac{1}{	ext{[Glucose]}}$$

Question 15

Which of the following best describes alternative RNA splicing?

Accepted Answer

It allows a single gene to code for multiple proteins by including or excluding different exons.

Question 16

Which of the following is a plausible consequence of DNA methylation during development?

Accepted Answer

Silencing of specific genes, leading to cell differentiation.

Question 17

Which of the following is TRUE about repressible operons?

Accepted Answer

They are usually active and require a corepressor to turn them off.

Question 18

Which of the following best explains why proto-oncogenes are present in all cells?

Accepted Answer

Proto-oncogenes are necessary for the normal control of cell growth and division.

Question 19

Which of the following would be most likely to lead to cancer?

Accepted Answer

Amplification of a proto-oncogene and inactivation of a tumor-suppressor gene.

Regulation of Gene Expression: Prokaryotic and Eukaryotic Mechanisms

Study Guide - Practice Questions