Avery-MacLeod-McCarty Experiment

In 1944, the researchers Oswald Avery, Colin MacLeod and Maclyn McCarty, working at the Rockefeller Institute, extended Frederick Griffith's earlier transformation experiments by systematically purifying and destroying different chemical components of the transforming substance from virulent pneumococcus bacteria, including proteins, RNA and DNA, to determine which one carried the transforming property. They found that only the destruction of DNA eliminated the bacteria's ability to transform harmless strains into virulent ones, providing the first direct experimental evidence that DNA, rather than protein as many scientists of the time expected, is the molecule that carries hereditary information. The finding was met with considerable skepticism at the time and took years to be widely accepted within the scientific community.