Which term describes the process in which one strain of bacteria is changed by DNA from another strain?

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

Answer: (C)

Transformation is the process by which bacteria take up DNA from their surroundings and incorporate it into their own genome, so one strain is changed by genetic material from another. This requires the recipient cell to be “competent,” ready to take up naked DNA, and the incoming DNA can recombine with the recipient’s chromosome to create new traits. This horizontal gene transfer contrasts with transduction, which uses a bacteriophage to move DNA between cells, and conjugation, which transfers DNA through direct cell-to-cell contact, usually via a pilus. Mutation, on the other hand, is a change that occurs within the organism’s own DNA without acquiring external DNA.