- A Gene flow that occurs specifically between members of the same species through ordinary sexual reproduction, a description of vertical inheritance rather than the mechanisms HGT actually uses
- B Transfer of genetic material between organisms other than by parent-to-offspring inheritance; occurs via conjugation, transformation, transduction; explains rapid spread of antibiotic resistance
- C Horizontal gene transfer is sometimes thought to be entirely impossible within bacterial populations, despite conjugation, transformation, and transduction being well-documented mechanisms driving it
- D Horizontal gene transfer is sometimes thought to occur mainly within plant species, rarely documented in bacteria, despite HGT being the principal route by which antibiotic resistance genes spread
Correct answer: B. Transfer of genetic material between organisms other than by parent-to-offspring inheritance; occurs via conjugation, transformation, transduction; explains rapid spread of antibiotic resistance
Explanation: HGT (lateral gene transfer): DNA transfer between non-parent-offspring organisms. Bacterial mechanisms: (1) Conjugation (F factor/plasmid transfer through pili); (2) Transformation (uptake of free DNA); (3) Transduction (bacteriophage-mediated). Consequences: (1) Antibiotic resistance genes spread globally in decades; (2) Prokaryote phylogeny is a web, not a tree; (3) Mitochondria and chloroplast genomes in eukaryotes represent ancient HGT from endosymbiosis events.
Concept context
Origin of life, Darwin's theory, natural selection, speciation, and evidence for evolution.