Question 1

Which of the following best describes a constitutive gene in bacteria?

Accepted Answer

A gene that is always expressed, regardless of environmental conditions.

Question 2

In the regulation of arginine biosynthesis in prokaryotes, what role does arginine play?

Accepted Answer

Arginine acts as a corepressor, binding to the repressor to block transcription.

Question 3

Which structural motif is commonly found in prokaryotic DNA-binding proteins that regulate transcription?

Accepted Answer

Helix-turn-helix motif

Question 4

A mutation that results in the substitution of one base for another, causing a change in a single amino acid in the protein, is called:

Accepted Answer

Missense mutation

Question 5

Which of the following is a consequence of a frameshift mutation?

Accepted Answer

The reading frame of the mRNA is altered, potentially changing all downstream amino acids.

Question 6

In the lac operon, what is the effect of allolactose binding to the LacI repressor?

Accepted Answer

It causes the repressor to release from the operator, allowing transcription to proceed.

Question 7

Which process involves the uptake of free DNA from the environment by a bacterial cell?

Accepted Answer

Transformation

Question 8

A scientist exposes bacteria to UV light, resulting in increased mutation rates. What type of mutation is this?

Accepted Answer

Induced mutation

Question 9

Which of the following is TRUE about transposons?

Accepted Answer

They are DNA sequences that can move from one location to another within the genome.

Question 10

In a two-component regulatory system, what is the primary function of the sensor histidine kinase?

Accepted Answer

To sense environmental signals and phosphorylate the response regulator.

Question 11

Which of the following best describes horizontal gene transfer in bacteria?

Accepted Answer

Transfer of genes between neighboring bacteria, possibly of different species.

Question 12

A mutation that does NOT change the amino acid sequence of the encoded protein is called:

Accepted Answer

Silent mutation

Question 13

Which equation correctly represents the process of transcription in bacteria?

Accepted Answer

$$DNA \rightarrow mRNA$$

Question 14

Which of the following is a function of chaperone proteins in bacteria?

Accepted Answer

They assist in the proper folding of other proteins.

Question 15

During conjugation, what is required for DNA transfer between bacterial cells?

Accepted Answer

Cell-to-cell contact

Question 16

Which of the following best explains the effect of a nonsense mutation?

Accepted Answer

It introduces a premature stop codon, truncating the protein.

Question 17

Which process is DNase sensitive and involves the uptake of naked DNA?

Accepted Answer

Transformation

Question 18

What is the role of the operator region in a bacterial operon?

Accepted Answer

It is the binding site for regulatory proteins such as repressors.

Question 19

Which of the following is TRUE about homologous recombination in bacteria?

Accepted Answer

It requires two DNA molecules with extensive sequence similarity.

Question 20

A bacterial cell acquires antibiotic resistance from a neighboring cell of a different species. Which genetic process most likely occurred?

Accepted Answer

Horizontal gene transfer

Exam 2 (Lecture 10/11) Gene Regulation and Transcriptional Control in Bacteria

Study Guide - Practice Questions