Question 1

Which of the following best explains how two cells with the same genome can have different functions in a multicellular organism?

Accepted Answer

They express different genes due to differential gene expression.

Question 2

In the trp operon of E. coli, what happens when tryptophan is present in high concentrations?

Accepted Answer

Tryptophan acts as a corepressor, activating the repressor and shutting off transcription.

Question 3

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

Accepted Answer

The lac repressor is inactivated by allolactose, allowing transcription to occur.

Question 4

Which of the following best describes the role of transcription factors in eukaryotic gene expression?

Accepted Answer

They bind to DNA and help regulate the initiation of transcription by RNA polymerase.

Question 5

A mutation causes the trp repressor protein to be unable to bind tryptophan. What is the most likely outcome?

Accepted Answer

The trp operon will be permanently active, regardless of tryptophan levels.

Question 6

Which of the following is true regarding DNA methylation in eukaryotes?

Accepted Answer

It is associated with reduced transcription and long-term gene inactivation.

Question 7

Which of the following best describes an inducible operon?

Accepted Answer

It is usually off and can be turned on by an inducer.

Question 8

In a scenario where a bacterial cell is exposed to both glucose and lactose, what is the expected activity of the lac operon?

Accepted Answer

The lac operon will be inactive because glucose represses its activation even if lactose is present.

Question 9

Which of the following is a function of enhancers in eukaryotic gene regulation?

Accepted Answer

They are distal control elements that increase transcription when bound by activators.

Question 10

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

Accepted Answer

Repressible operons are usually on and can be turned off; inducible operons are usually off and can be turned on.

Question 11

A scientist discovers a mutation that 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 permanently on, regardless of lactose presence.

Question 12

Which of the following is an example of negative gene regulation?

Accepted Answer

A repressor protein binding to the operator to block transcription.

Question 13

Which of the following is true about the life span of mRNA in eukaryotic cells?

Accepted Answer

Nucleotide sequences in the 3' untranslated region (UTR) influence mRNA stability.

Question 14

Which of the following best describes the process of cell differentiation during embryonic development?

Accepted Answer

Cells express different genes, leading to specialized structure and function.

Question 15

Which of the following is a correct statement about cytoplasmic determinants?

Accepted Answer

They are maternal substances in the egg that influence early development by affecting gene expression.

Question 16

Which of the following is a real-life example of feedback inhibition in bacteria?

Accepted Answer

The end product of a metabolic pathway inhibits the activity of an enzyme earlier in the pathway.

Question 17

Which of the following best describes the function of a corepressor in the trp operon?

Accepted Answer

It binds to the repressor protein, activating it so it can bind the operator and block transcription.

Question 18

Which of the following is a likely consequence of abnormal gene expression in multicellular organisms?

Accepted Answer

Development of diseases such as cancer.

Question 19

Which of the following is true about master regulatory genes?

Accepted Answer

They determine cell fate by controlling the expression of other genes.

Question 20

Which of the following best describes the role of induction during embryonic development?

Accepted Answer

Signal molecules from embryonic cells cause changes in gene expression in nearby target cells.

Chapter 18: Regulation of Gene Expression – Study Notes

Study Guide - Practice Questions