Question 1

Which of the following best describes the process of generalized transduction in bacteria?

Accepted Answer

Transfer of any portion of the host genome to a recipient cell by a bacteriophage, often due to accidental packaging of host DNA into the phage particle.

Question 2

A scientist exposes a bacterial culture to ultraviolet (UV) light. Which of the following DNA lesions is most likely to result from this treatment?

Accepted Answer

Formation of pyrimidine dimers, especially between adjacent thymine or cytosine bases.

Question 3

Which of the following statements about the lac operon in Escherichia coli is correct?

Accepted Answer

The lac operon is induced in the presence of lactose and absence of glucose, allowing for the catabolism of lactose.

Question 4

A bacterial strain is unable to grow on minimal medium unless tryptophan is added. What is the most accurate term for this strain?

Accepted Answer

Auxotroph

Question 5

Which of the following best explains why frameshift mutations are often more deleterious than point mutations?

Accepted Answer

Frameshift mutations change the reading frame, altering every amino acid downstream of the mutation.

Question 6

Which of the following is a key requirement for successful bacterial transformation?

Accepted Answer

The recipient cell must be competent to take up free DNA from the environment.

Question 7

A researcher uses replica plating to identify mutants that cannot synthesize histidine. Which of the following best describes the principle behind this technique?

Accepted Answer

Screening for mutants by comparing growth on complete medium and medium lacking histidine.

Question 8

Which of the following statements about the human gut microbiome is correct?

Accepted Answer

The gut microbiome can influence host gene expression and is associated with conditions such as obesity and type 2 diabetes.

Question 9

Which of the following best describes the function of the RecA protein in homologous recombination?

Accepted Answer

RecA binds to single-stranded DNA and facilitates strand invasion and exchange with homologous regions.

Question 10

A patient with recurrent Clostridioides difficile infection is treated with a fecal microbiota transplant (FMT). What is the primary rationale for this therapy?

Accepted Answer

To restore a healthy and diverse gut microbiome that can outcompete C. difficile.

Question 11

Which of the following is a characteristic of conjugation in bacteria?

Accepted Answer

It requires direct cell-to-cell contact and is often mediated by an F plasmid.

Question 12

Which of the following best describes the hygiene hypothesis?

Accepted Answer

Exposure to excessive hygiene and lack of early infections may lead to immune system imbalances and increased risk of allergies and autoimmune diseases.

Question 13

A missense mutation occurs in a gene. Which of the following best describes the likely outcome?

Accepted Answer

The mutation changes a single amino acid in the protein, which may or may not affect function.

Question 14

Which of the following is a plausible consequence of a nonsense mutation in a coding region?

Accepted Answer

The protein is truncated due to the introduction of a premature stop codon.

Question 15

Which of the following best explains why insertion or deletion of three base pairs in a gene is usually less harmful than insertion or deletion of one or two base pairs?

Accepted Answer

Three base pair changes do not alter the reading frame, so only one amino acid is added or removed.

Question 16

Which of the following is a function of T-helper 1 (Th1) cells in the immune system?

Accepted Answer

They activate immune cells to destroy infected, cancerous, or diseased body cells, especially those harboring intracellular microbes.

Question 17

A chemical mutagen is found to cause insertions and deletions by intercalating between DNA base pairs. Which class of mutagen does this chemical most likely belong to?

Accepted Answer

Intercalating agents such as acridines or ethidium bromide

Question 18

Which of the following equations best represents the frequency of transduction events if 1 cell in $$10^7 is $$transduced?

Accepted Answer

$$f = \frac{1}{10^7$}$$

Question 19

Which of the following statements about the regulation of the trp operon is correct?

Accepted Answer

The trp operon is a repressible operon that is turned off when tryptophan is abundant.

Question 20

A bacterial cell is exposed to a base analog mutagen. Which of the following is the most likely result?

Accepted Answer

Increased frequency of point mutations due to faulty base pairing during DNA replication.

Genetics of Bacteria, Mutations, and the Human Microbiome: Study Notes

Study Guide - Practice Questions

Study Guide - Flashcards