Horizontal vs. vertical gene transfer — definition: Which statement correctly describes horizontal gene transfer (HGT)?

Introduction / Context:
Horizontal gene transfer reshapes microbial genomes by introducing new genes outside traditional inheritance. Distinguishing HGT from vertical transmission and basic molecular processes is essential in microbiology and genomics.

Given Data / Assumptions:

• HGT includes transformation, transduction, and conjugation.
• Vertical transfer is parent-to-progeny inheritance.
• Central dogma terms (translation and transcription) describe molecular synthesis, not inheritance.

Concept / Approach:

Choose the option that explicitly states gene flow between mature, non-parental organisms. Exclude definitions that refer to vertical inheritance or molecular synthesis steps.

Step-by-Step Solution:

Verification / Alternative check:

Examples include plasmid-mediated antibiotic resistance spread or phage-borne toxin genes, both occurring between mature cells.

Why Other Options Are Wrong:

Options A and D describe biochemical processes, not inheritance.

Option C defines vertical inheritance, not horizontal transfer.

Common Pitfalls:

Using “horizontal” for any lateral spread including clonal expansion; true HGT requires DNA movement between individuals outside parent–offspring relationships.

Final Answer:

Transmission of genetic information from one independent, mature organism to another