Question 1

Which of the following best describes the nucleoid in a bacterial cell?

Accepted Answer

A region in the cytoplasm where the bacterial chromosome is located, not surrounded by a membrane.

Question 2

Which of the following is a typical gene found on a bacterial plasmid?

Accepted Answer

Gene for antibiotic resistance.

Question 3

During DNA replication in E. coli, how is it possible for the cell to divide every 30 minutes even though it takes 38 minutes to replicate its DNA?

Accepted Answer

E. coli initiates new rounds of DNA replication before the previous round is completed.

Question 4

Which end of a nucleic acid strand has a free phosphate group attached to the 5' carbon of the sugar?

Accepted Answer

5' end

Question 5

A mutation is best defined as:

Accepted Answer

A permanent change in the nucleotide sequence of DNA.

Question 6

Which of the following statements about mutation rates in bacteria is correct?

Accepted Answer

Mutations are rare in individual cells but common in large populations.

Question 7

Which of the following is an example of an induced mutation?

Accepted Answer

A thymine dimer forms after exposure to ultraviolet (UV) light.

Question 8

What is the primary purpose of the Ames test?

Accepted Answer

To identify chemicals that can cause mutations.

Question 9

In the Ames test, why are liver enzymes often added to the test mixture?

Accepted Answer

To simulate metabolic activation of chemicals as would occur in mammals.

Question 10

Which of the following is NOT a type of horizontal gene transfer (HGT) in bacteria?

Accepted Answer

Binary fission

Question 11

Which type of horizontal gene transfer requires cell-to-cell contact and involves a pilus?

Accepted Answer

Conjugation

Question 12

In Griffith’s experiment, what was the key finding regarding transformation?

Accepted Answer

Non-virulent bacteria became virulent when mixed with heat-killed virulent bacteria.

Question 13

Which of the following statements about homologous recombination in bacteria is correct?

Accepted Answer

It allows integration of foreign DNA into the chromosome if there is sufficient sequence similarity.

Question 14

Which type of horizontal gene transfer uses a virus as a vector?

Accepted Answer

Transduction

Question 15

During generalized transduction, what is the first step in the process?

Accepted Answer

A bacteriophage accidentally packages bacterial DNA into a phage particle.

Question 16

Which of the following best explains why horizontal gene transfer is beneficial to bacteria?

Accepted Answer

It increases genetic diversity and can provide new traits such as antibiotic resistance.

Question 17

Which of the following must occur for horizontal gene transfer to result in a permanent genetic change in a bacterial population?

Accepted Answer

The transferred DNA must be integrated into the chromosome or maintained as a replicon.

Question 18

Which of the following is a key difference between conjugation and transformation?

Accepted Answer

Conjugation requires direct cell-to-cell contact, while transformation involves uptake of free DNA.

Question 19

A researcher exposes E. coli to a chemical and observes an increased number of revertant colonies in an Ames test. What does this indicate about the chemical?

Accepted Answer

The chemical is likely a mutagen.

Question 20

If a bacterium acquires a plasmid carrying a gene for antibiotic resistance via conjugation, which of the following equations best represents the change in the population's resistance frequency, assuming $$N is $$the total population and $$n is $$the number of resistant cells after conjugation?

Accepted Answer

$$f = \frac{n}{N}$$

Microbial Genetics: Study Guide for Chapter 7 (BIO 2350)

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