Question 1

Which of the following best describes the sequence of events in gene expression leading to an activated protein?

Accepted Answer

DNA $$\rightarrow$$ mRNA $$\rightarrow$$ Protein $$\rightarrow$$ Activated Protein

Question 2

Transcriptional control of gene expression is considered:

Accepted Answer

Efficient but slow

Question 3

Which level of gene regulation is the fastest in response to environmental changes?

Accepted Answer

Post-translational control

Question 4

In the lac operon, what is the role of the regulatory gene?

Accepted Answer

It codes for a protein that regulates the expression of the operon.

Question 5

Which of the following best describes negative control in gene regulation?

Accepted Answer

A regulatory protein inhibits transcription by binding to DNA.

Question 6

Why is the ability to regulate gene expression important for bacteria?

Accepted Answer

It allows them to adapt to changing environments as single-cell organisms.

Question 7

Which of the following is true about the lac operon in E. coli?

Accepted Answer

It is expressed only when lactose is present and glucose is absent.

Question 8

Allosteric regulation involves:

Accepted Answer

A molecule binding to a protein and changing its shape.

Question 9

Which of the following is an example of a constitutively expressed gene?

Accepted Answer

A gene that is always transcribed regardless of environmental conditions.

Question 10

The SOS response in bacteria is regulated by:

Accepted Answer

A specific regulatory system that controls the expression of SOS genes.

Question 11

Which of the following mechanisms of gene regulation is most likely to result in a rapid cellular response to DNA damage?

Accepted Answer

Post-translational control

Question 12

If a mutation prevents the lac repressor from binding to the operator, what is the most likely outcome?

Accepted Answer

The lac operon will be expressed even in the absence of lactose.

Question 13

Which of the following best explains why transcriptional control is considered efficient?

Accepted Answer

It prevents unnecessary synthesis of mRNA and proteins.

Question 14

A regulatory gene that is constitutively expressed will:

Accepted Answer

Continuously produce its regulatory protein regardless of environmental conditions.

Question 15

Which of the following is NOT a mechanism of gene regulation?

Accepted Answer

DNA replication control

Question 16

In the context of the lac operon, what is the function of the operator sequence?

Accepted Answer

It is the DNA region where the repressor binds to block transcription.

Question 17

Which of the following scenarios best illustrates translational control?

Accepted Answer

A cell produces mRNA but translation is inhibited until a specific signal is received.

Question 18

Which of the following equations best represents the central dogma of molecular biology?

Accepted Answer

$$DNA \rightarrow mRNA \rightarrow Protein$$

Question 19

A bacterium exposed to a new sugar in its environment begins to express genes for enzymes that metabolize the sugar. This is an example of:

Accepted Answer

Inducible gene regulation

Question 20

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

Accepted Answer

It is an example of an inducible operon regulated by both positive and negative control mechanisms.

Gene Regulation Mechanisms in Prokaryotes

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