Question 1

Which of the following best describes a constitutive gene?

Accepted Answer

A gene that is expressed at a constant level in all conditions over time.

Question 2

In the lac operon, what is the role of cAMP in transcriptional regulation?

Accepted Answer

cAMP binds to the catabolite activator protein (CAP), allowing it to activate transcription of the lac operon.

Question 3

Which small effector molecule increases transcription by binding to an activator protein or a repressor protein?

Accepted Answer

Inducer

Question 4

A mutation causes the Shine-Dalgarno sequence of an mRNA to be blocked by a repressor protein. What is the most likely outcome?

Accepted Answer

Translation initiation will be inhibited, reducing protein synthesis.

Question 5

Which of the following is TRUE regarding feedback inhibition in post-translational regulation?

Accepted Answer

The first enzyme in the pathway is inhibited by the final product at its allosteric site.

Question 6

In the trp operon, what happens when tryptophan levels are high?

Accepted Answer

The repressor binds tryptophan, becomes active, and blocks transcription.

Question 7

Which of the following is NOT a method of gene expression regulation?

Accepted Answer

Replication regulation

Question 8

A patient is found to have a mutation that prevents covalent modification of enzymes. Which process is most likely to be affected?

Accepted Answer

Post-translational regulation

Question 9

Which statement best describes the function of antisense RNA in translational regulation?

Accepted Answer

It binds to another gene's mRNA, inhibiting its function.

Question 10

Which equation best represents the relationship between enzyme activity and feedback inhibition in a metabolic pathway?

Accepted Answer

$$v = \frac{V_{max}[S]}{K_m + [S] + \frac{[I]}{K_i}}$$

Question 11

Which of the following scenarios would most likely result in increased transcription of the lac operon?

Accepted Answer

Low glucose and high lactose

Question 12

What is the primary effect of a corepressor molecule in gene regulation?

Accepted Answer

It binds to a repressor protein and enables it to block transcription.

Question 13

Which of the following is an example of positive control in transcriptional regulation?

Accepted Answer

An activator protein binding to DNA to increase transcription.

Question 14

In the ara operon, what is the effect of arabinose binding to the C protein?

Accepted Answer

It changes the conformation of the C protein, allowing it to activate transcription.

Question 15

Which of the following statements about post-translational regulation is correct?

Accepted Answer

It regulates the activity of proteins that are already present in the cell.

Question 16

A scientist discovers a new inhibitor molecule that binds to an activator protein. What is the most likely effect on gene expression?

Accepted Answer

Transcription will decrease because the activator is inhibited.

Question 17

Which of the following best explains why post-translational regulation is considered faster than transcriptional or translational regulation?

Accepted Answer

It acts on proteins that are already synthesized, allowing immediate changes in activity.

Question 18

Which process is most likely to be affected if antisense RNA is overexpressed in a cell?

Accepted Answer

Translational regulation

Question 19

Which of the following is a reversible covalent modification that can regulate enzyme activity post-translationally?

Accepted Answer

Phosphorylation

Question 20

A bacterial cell is exposed to both high levels of glucose and lactose. What is the expected transcriptional activity of the lac operon?

Accepted Answer

Low transcription because glucose inhibits cAMP production.

Regulation of Gene Expression: Transcriptional, Translational, and Post-Translational Control

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