Hershey-Chase Experiment

Alfred Hershey and Martha Chase labeled the protein coat of a virus that infects bacteria with radioactive sulfur and its DNA core with radioactive phosphorus, let the viruses infect bacteria, then spun the mixture in a blender and a centrifuge to knock loose and separate whatever had stayed outside the bacterial cells from whatever had gone in. The phosphorus label, marking DNA, entered the bacteria and was passed on to new virus particles; the sulfur label, marking protein, stayed outside. Since a virus needs to inject only its genetic material to reprogram a cell, the result showed that DNA, not protein, is the molecule that carries genetic information, closing a debate that had run for decades.