Define transformation in bacterial genetics.

• A. Transformation is the uptake of naked DNA from the environment.
• B. Transformation is viral DNA integrated into bacterial chromosome.
• C. Transformation is direct DNA transfer via pili.
• D. Transformation is exchange of plasmids between cells in a mating pair.

Answer: (A)

Transformation in bacterial genetics refers to the uptake of naked DNA from the environment by competent cells. Some bacteria become capable of taking up free DNA from their surroundings, and once inside, that DNA can either recombine into the host genome or exist as a plasmid, introducing new genetic traits to the recipient. This process is distinct from other horizontal gene transfer methods: transduction uses bacteriophages to move DNA, while conjugation requires direct cell-to-cell contact and typically transfers plasmids (or chromosomal DNA via special donor strains). The option describing uptake of naked DNA from the environment captures the essence of transformation, which is why it is the best choice.