Question 1

Which of the following best describes the Central Dogma of Molecular Biology?

Accepted Answer

DNA is transcribed into mRNA, which is then translated into protein.

Question 2

A mutation changes a codon from $$	ext{UAC} ($$tyrosine) to $$	ext{UAA} ($$stop codon). What type of mutation is this?

Accepted Answer

Nonsense mutation

Question 3

Which method is used to identify auxotrophic mutants that require a specific nutrient for growth?

Accepted Answer

Negative/indirect selection using replica plating

Question 4

In the Ames test, what does the appearance of bacterial colonies on a histidine-free medium indicate?

Accepted Answer

The tested chemical is a mutagen that caused a mutation allowing histidine synthesis.

Question 5

Which of the following best describes a frameshift mutation?

Accepted Answer

A nucleotide is added or deleted, shifting the reading frame and altering all downstream amino acids.

Question 6

Which type of horizontal gene transfer involves the uptake of naked DNA from the environment by a prokaryote?

Accepted Answer

Transformation

Question 7

During conjugation, what structure is used to bring two prokaryotes into contact for DNA transfer?

Accepted Answer

Conjugation pilus

Question 8

Which of the following statements about transposons is correct?

Accepted Answer

Transposons move within the genome using the enzyme transposase.

Question 9

A bacterium acquires antibiotic resistance by receiving a plasmid from another bacterium. Which mechanism is responsible?

Accepted Answer

Conjugation

Question 10

Which of the following best describes generalized transduction?

Accepted Answer

A virus transfers any piece of chromosomal DNA by accidentally packaging it into a viral particle.

Question 11

In Griffith’s experiment, which process allowed non-virulent bacteria to become virulent after exposure to heat-killed virulent bacteria?

Accepted Answer

Transformation

Question 12

Which of the following is an example of vertical transmission?

Accepted Answer

A parent cell passes its genetic material to its daughter cells during cell division.

Question 13

A mutation changes the DNA sequence $$	ext{GAA} ($$glutamic acid) to $$	ext{GAG} ($$glutamic acid). What type of mutation is this?

Accepted Answer

Silent mutation

Question 14

Which scenario best illustrates specialized transduction?

Accepted Answer

A virus excises from the host chromosome and carries specific neighboring bacterial genes to a new host.

Question 15

A frameshift mutation occurs when two nucleotides are deleted from a gene. What is the likely outcome for the protein?

Accepted Answer

All amino acids after the mutation point will be changed, likely resulting in a nonfunctional protein.

Question 16

Which of the following is NOT a method of horizontal gene transfer?

Accepted Answer

Vertical transmission

Question 17

A missense mutation changes the DNA sequence $$	ext{AAA} ($$lysine) to $$	ext{AGA} ($$arginine). What is the potential impact on the protein?

Accepted Answer

The protein will have a different amino acid, which may affect its function depending on the location and properties of the new amino acid.

Question 18

Which enzyme is required for transposons to move within the genome?

Accepted Answer

Transposase

Question 19

A scientist wants to select for bacteria that are resistant to a new antibiotic. Which method should they use?

Accepted Answer

Positive selection using a selective medium containing the antibiotic

Question 20

Which of the following best explains why frameshift mutations are usually more harmful than missense mutations?

Accepted Answer

Frameshift mutations change the reading frame, altering all downstream amino acids and often resulting in a nonfunctional protein.

Mechanisms of Microbial Genetics & Horizontal Gene Transfer – Guided Study

Study Guide - Practice Questions