Which set lists the three major mechanisms by which bacteria acquire new genes?

• A. Transformation, transcription, and translation
• B. Transduction, replication, and transcription
• C. Conjugation, sporulation, and germination
• D. Transformation, transduction, and conjugation

Answer: (D)

Acquiring new genes in bacteria mainly happens through horizontal gene transfer, not just by ordinary cell reproduction. The three major routes are transformation, transduction, and conjugation. Transformation is when a bacterium takes up free DNA from its surroundings and incorporates it into its genome or maintains it as a plasmid, provided the cell is competent. Transduction occurs when a bacteriophage carries pieces of bacterial DNA from one cell to another during infection, enabling gene transfer between bacteria. Conjugation is direct DNA transfer between cells, usually via a pilus, often involving plasmids like the F factor that move from a donor to a recipient and introduce new traits.

These pathways together explain how bacteria can rapidly acquire new abilities, such as antibiotic resistance or novel metabolic capabilities. In contrast, transcription and translation are processes of expressing genes, replication copies DNA within a cell, and sporulation/germination are developmental states, none of which move genetic material between cells.