Question 1

Which of the following best describes the main function of regulatory elements in gene expression?

Accepted Answer

They are DNA sequences that are not transcribed but play a role in regulating other nucleotide sequences.

Question 2

In the lac operon of E. coli, what is the effect of high glucose and absence of lactose on the transcription of lac genes?

Accepted Answer

Transcription is repressed because the repressor is bound to the operator and CAP is inactive.

Question 3

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

Accepted Answer

It is a repressible operon that is turned off when tryptophan is abundant.

Question 4

Which of the following best explains why muscle cells and fat cells in an individual contain the same DNA but perform different functions?

Accepted Answer

They express different sets of genes due to differential gene expression.

Question 5

Which of the following is a characteristic of constitutive gene expression?

Accepted Answer

Genes are continuously expressed under normal cellular conditions.

Question 6

Which of the following best describes the mechanism by which DNA-binding proteins recognize specific DNA sequences?

Accepted Answer

By forming hydrogen bonds with DNA bases, primarily in the major groove.

Question 7

A mutation in the operator region of the lac operon prevents the repressor from binding. What is the most likely outcome?

Accepted Answer

The lac genes will be transcribed continuously, regardless of lactose presence.

Question 8

Which of the following is true about attenuation in the trp operon?

Accepted Answer

It allows for fine-tuned regulation of transcription based on tryptophan levels.

Question 9

Which equation best represents the central dogma of molecular biology?

Accepted Answer

$$DNA \rightarrow RNA \rightarrow Protein$$

Question 10

Which of the following is an example of positive control of gene expression?

Accepted Answer

An activator protein binds to DNA and stimulates transcription.

Question 11

In the context of gene regulation, what is the role of the activation domain (AD) of a transcription factor?

Accepted Answer

It interacts with other proteins to facilitate the assembly of the transcription complex.

Question 12

Which of the following best describes an inducible operon?

Accepted Answer

Transcription is usually off and needs to be turned on.

Question 13

Which of the following is a real-world example of a gene that is constitutively expressed?

Accepted Answer

The gene encoding actin, a cytoskeletal protein.

Question 14

Which of the following statements about the catabolite activator protein (CAP) in the lac operon is correct?

Accepted Answer

CAP exerts positive control by binding to the promoter when cAMP levels are high.

Question 15

Which of the following best explains why abnormalities in gene expression can lead to diseases such as cancer?

Accepted Answer

Abnormal gene expression can result in the inappropriate activation or repression of genes involved in cell growth and division.

Question 16

Which of the following is NOT a function that genetic material must be able to perform?

Accepted Answer

Catalyze all metabolic reactions in the cell.

Question 17

Which of the following best describes the difference between structural genes and regulatory genes?

Accepted Answer

Structural genes encode proteins or RNAs with cellular functions, while regulatory genes encode products that affect the expression of other genes.

Question 18

Which of the following protein structures is primarily responsible for recognizing and binding to specific DNA sequences?

Accepted Answer

Tertiary structure

Question 19

Which of the following is a plausible outcome if a mutation prevents the formation of the 3-4 hairpin loop in the trp operon leader sequence?

Accepted Answer

Transcription will continue, allowing expression of trp structural genes even when tryptophan is abundant.

Gene Regulation in Prokaryotes: Operons, DNA-Binding Proteins, and Mechanisms of Control

Study Guide - Practice Questions