Which experiment demonstrated transformation in bacteria and hinted at DNA as the genetic material?

• A. Griffith's Transformation Experiment
• B. Avery-MacLeod-McCarty Study
• C. Hershey-Chase Blender Experiment
• D. Watson-Crick Model

Answer: (A)

Transformation in bacteria is shown when a cell takes up external DNA and changes its traits. In Griffith’s experiment with Streptococcus pneumoniae, a mixture of heat-killed virulent bacteria and live non-virulent bacteria somehow produced new living bacteria that were virulent. The non-virulent cells acquired genetic material from the dead cells, changing their phenotype, which demonstrated that DNA or another genetic substance could move between cells and alter their characteristics. This result suggested that the genetic material could be transferred between organisms, hinting that DNA might be the carrier of heredity. The other options fit different milestones: Avery, MacLeod, and McCarty showed that DNA is the transforming substance, Hershey and Chase demonstrated DNA as the genetic material in viruses, and Watson and Crick proposed the DNA double-helix structure. Thus, Griffith’s transformation experiment is the one that first demonstrated transformation in bacteria and pointed toward DNA as the genetic material.