$$\text{DNA} \rightarrow \text{RNA} \rightarrow \text{Protein}$$

Question 1

Which enzyme is responsible for introducing negative supercoils into bacterial DNA, thereby compacting the genome for cellular accommodation?

Accepted Answer

DNA gyrase

Question 2

In the central dogma of molecular biology, which sequence correctly represents the flow of genetic information?

Accepted Answer

$$	ext{DNA} ightarrow 	ext{RNA} ightarrow 	ext{Protein}$$

Question 3

Which of the following best describes a plasmid?

Accepted Answer

A circular or linear double-stranded DNA molecule that replicates independently of the chromosome

Question 4

What is the primary function of the FtsZ protein during bacterial cell division?

Accepted Answer

It forms a ring at the cell center, guiding septum formation

Question 5

Which antibiotic targets DNA gyrase, thereby inhibiting bacterial DNA replication?

Accepted Answer

Quinolones (e.g., ciprofloxacin)

Question 6

A missense mutation is best defined as:

Accepted Answer

A mutation that changes one amino acid in the polypeptide sequence

Question 7

Which mechanism allows bacteria to rapidly acquire new traits, such as antibiotic resistance, from unrelated cells?

Accepted Answer

Horizontal gene transfer

Question 8

During transformation in bacteria, what is required for the integration of foreign DNA into the host chromosome?

Accepted Answer

RecA protein

Question 9

Which of the following is a major mechanism of antibiotic resistance involving the removal of antibiotics from the cell?

Accepted Answer

Efflux pumps

Question 10

What is the role of cyclic di-guanosine monophosphate (c-di-GMP) in biofilm formation?

Accepted Answer

It promotes extracellular polysaccharide production and reduces flagellar activity

Question 11

Which of the following best describes a temperate bacteriophage?

Accepted Answer

A virus that can integrate its genome into the host chromosome and establish lysogeny

Question 12

Which class of viral genome according to the Baltimore scheme is most common among prokaryotic viruses?

Accepted Answer

Class I: dsDNA

Question 13

What is the primary function of the Lux operon in Aliivibrio fischeri?

Accepted Answer

It encodes bioluminescence/luciferase enzymes

Question 14

Which of the following is true about viroids?

Accepted Answer

They are small, circular, single-stranded RNA molecules that cause plant diseases

Question 15

Which protein is essential for homologous recombination in bacteria, facilitating genetic exchange between DNA molecules?

Accepted Answer

RecA

Question 16

Which of the following is a characteristic of prions?

Accepted Answer

They are infectious proteins with no nucleic acid component

Question 17

Which process is used to detect and count viruses by observing clear zones of cell lysis on a lawn of host cells?

Accepted Answer

Plaque assay

Question 18

Which of the following is a real-world consequence of biofilm formation by Pseudomonas aeruginosa in cystic fibrosis patients?

Accepted Answer

Thick biofilms in the lungs increase pathogenicity and prevent antibiotic penetration

Question 19

Which mechanism of horizontal gene transfer in bacteria requires cell-to-cell contact and is plasmid-encoded?

Accepted Answer

Conjugation

Question 20

Which type of mutation results in a shift of the reading frame, often scrambling the entire downstream polypeptide sequence?

Accepted Answer

Frameshift mutation

Molecular Information Flow, Genetic Elements, and Viral Diversity in Microbiology

Study Guide - Practice Questions