Question 1

Which of the following best describes the role of transcriptional control in bacterial gene expression?

Accepted Answer

It controls gene expression before the cell expends resources, but is the slowest form of regulation.

Question 2

In the lac operon, what is the function of the lacI gene product?

Accepted Answer

It encodes a repressor protein that binds to the operator and blocks RNA polymerase.

Question 3

Which equation correctly represents the flow of genetic information in a cell?

Accepted Answer

$$DNA \rightarrow mRNA \rightarrow protein \rightarrow activated\ protein$$

Question 4

A mutant E. coli strain produces β-galactosidase and galactoside permease even when lactose is absent. Which gene is most likely defective?

Accepted Answer

lacI

Question 5

What would happen to the lac operon if the operator sequence was deleted?

Accepted Answer

The lac operon would be transcribed constitutively.

Question 6

Which of the following is a consequence of high glucose levels on the regulation of the lac operon?

Accepted Answer

Inducer exclusion prevents lactose from entering the cell.

Question 7

Which mechanism allows for the most rapid response to environmental changes in bacterial gene expression?

Accepted Answer

Post-translational control

Question 8

In the context of global gene regulation, what is a regulon?

Accepted Answer

A group of genes regulated by the same regulatory protein, but located at different sites on the chromosome.

Question 9

Which of the following best explains why the lac operon is considered a model system for gene regulation?

Accepted Answer

It demonstrates negative control by repressors and the importance of regulatory sequences in DNA.

Question 10

Which of the following statements about the CAP protein and cAMP in positive control of the lac operon is correct?

Accepted Answer

CAP-cAMP complex stimulates RNA polymerase binding when glucose is low.

Question 11

Which of the following is NOT a level at which eukaryotes can regulate gene expression?

Accepted Answer

Inducer exclusion

Question 12

What is the effect of DNA methylation on gene expression in eukaryotes?

Accepted Answer

It condenses chromatin and decreases gene expression.

Question 13

Which enzyme is responsible for adding acetyl groups to histones, leading to decondensed chromatin?

Accepted Answer

Histone acetyltransferase (HAT)

Question 14

A cell unable to produce histone proteins would most likely experience which of the following?

Accepted Answer

Its DNA could not be packed into the nucleus.

Question 15

Which of the following best describes epigenetic inheritance?

Accepted Answer

Inheritance of gene expression patterns due to chromatin modifications, not DNA sequence changes.

Question 16

In the context of the ara operon, what is the role of the AraC protein when arabinose is present?

Accepted Answer

AraC acts as an activator and stimulates transcription.

Question 17

Which of the following is a real-world example of epigenetic regulation affecting phenotype?

Accepted Answer

Florida carpenter ants with higher DNA methylation are smaller in size.

Question 18

Which of the following statements about chromatin structure in eukaryotes is correct?

Accepted Answer

DNA is wrapped around histones to form nucleosomes.

Question 19

Which process must occur for RNA polymerase to access DNA and initiate transcription in eukaryotes?

Accepted Answer

Chromatin must be decondensed by chromatin remodeling.

Control of Gene Expression in Bacteria and Eukaryotes

Guida di studio - Domande di pratica