Practice question

Horizontal gene transfer comprises mechanisms that move DNA between non-parental cells within same generation: transformation uptake of naked DNA, transduction via bacteriophage accidental packaging, and conjugation via direct cell contact and plasmid transfer. Binary fission is not horizontal; it is vertical replication producing daughter cells. Transformation, transduction, and conjugation increase genetic diversity, spread antibiotic resistance, and allow mosaic genomes. Distinguishing horizontal from vertical mechanisms is crucial for tracing gene flow, mapping mobile elements, and understanding bacterial evolution beyond simple clonal descent.