What is the term for the uptake of environmental DNA by a bacterium resulting in a permanent genetic change?

• A. Transformation
• B. Transduction
• C. Conjugation
• D. Mutation

Answer: (A)

The concept being tested is horizontal gene transfer by taking up DNA from the environment and making a heritable change. When a bacterium takes up environmental DNA and that DNA recombines into its genome or is maintained as a replicating element, the new genetic information becomes a permanent part of that cell and its descendants. This specific process is transformation. It’s different from transduction, where a bacteriophage carries DNA from one cell to another, not environmental DNA; and from conjugation, which requires direct cell-to-cell contact and typically transfers plasmids. Mutation, meanwhile, is a change in DNA sequence that arises on its own or due to mutagens, not through uptake of external DNA.