Q.22 Which one of the following statements is INCORRECT with respect to bacterial conjugation?
(A) It facilitates transfer of genetic material
(B) It requires flagellum
(C) It can spread antibiotic resistance
(D) It can transfer virulence factors

Option (B) is the incorrect statement.

Bacterial conjugation is a key horizontal gene transfer mechanism where donor bacteria transfer plasmids or genetic material to recipient cells via direct contact.​

Option Analysis

(A) Genetic Material Transfer

Conjugation facilitates the transfer of plasmids like the F plasmid from F+ donor to F- recipient cells through a specialized pilus and Type IV secretion system. The process involves nicking the plasmid at oriT, transferring a single strand, and complementary strand synthesis in both cells.​

(B) Flagellum Requirement

Conjugation requires a sex pilus (conjugative pilus), not a flagellum, for establishing cell-to-cell contact and DNA transport. Flagella aid motility in specific cases like pLS20 plasmid in liquid media by signaling gene expression, but are not universally required.​

(C) Antibiotic Resistance Spread

Plasmids carrying antibiotic resistance genes spread rapidly via conjugation, even across species, contributing to multidrug resistance in pathogens.​

(D) Virulence Factors Transfer

Conjugative plasmids often carry virulence genes, enabling transfer of pathogenicity factors like toxins or adhesins between bacteria.​

Bacterial conjugation represents a cornerstone of microbial genetics, enabling bacterial conjugation genetic transfer that drives evolution and antibiotic resistance. For CSIR NET aspirants, understanding bacterial conjugation incorrect statements – especially misconceptions like flagellum involvement – is crucial for competitive exams. This SEO-optimized guide breaks down the process, evaluates each option, and highlights why one claim fails.

Core Mechanism of Bacterial Conjugation

Donor cells (F+) extend a sex pilus to contact recipients (F-), forming a mating bridge for single-stranded DNA transfer from conjugative plasmids. Key steps include relaxase nicking at oriT, T-strand translocation via Type IV secretion, and replication in both cells. Unlike transformation or transduction, it demands physical contact.​​

Why Flagellum Is Not Required (The Incorrect Statement)

Standard bacterial conjugation relies on pili, not flagella, for DNA conduit formation. Recent studies show flagellar rotation aids pLS20 plasmid transfer in Bacillus subtilis by inducing mating clusters in liquids, but this is plasmid-specific and not a general requirement. Exam contexts emphasize pilus as essential.​

Real-World Impacts: Resistance and Virulence

• Antibiotic Resistance: Conjugation disseminates resistance plasmids rapidly, even in biofilms, fueling global health crises.​

• Virulence Factors: Pathogenicity islands transfer toxins and adhesins, enhancing bacterial fitness.​

CSIR NET Exam Tips

Focus on distinguishing pili (conjugation) from flagella (motility). Practice questions test this nuance for horizontal gene transfer topics.​