Griffith's experiment

Griffith's experiment in 1928 demonstrated that bacteria can transfer genetic information. He worked with two types of pneumonia bacteria: one harmful (smooth) and one harmless (rough). When the heat-killed harmful bacteria were mixed with live harmless bacteria, the harmless bacteria transformed into harmful ones, able to cause disease. This showed that some "transforming principle" from the dead bacteria entered the living ones, changing their characteristics. Griffith's work was crucial in discovering that genetic material can be transferred between organisms, laying the foundation for molecular biology.