In 1944, after sixteen years Griffith’s experiment, Oswald Avery, colin Mac-leod and maclyn macarty purified the biochemical (proteins, DNA, RNA etc) from heat-killed s-strain cells to see which ones could transform live R- cells into S – cells.
They discovered that DNA alone From S bacteria caused R bacteria to became transformed. They also discovered that protein-digesting enzymes and RNA digesting enzymes did not affect transformation. So transforming substance was not a Protein or RNA. Digestion with DNA did inhibit transformation, suggested That DNA cause the transformation. Thus they conclude that DNA is the hereditary material.
Blender Experiment An elegant confirmation of the genetic nature of DNA came from an Experiment with E-coli phase T2. It is known as blender experiment Because a kitchen blender was used as a major piece of apparatus, Was performed by Alfred Hershey and Martha chase in 1952.They Demonstrated that DNA injected by a phase particle into a bacterium That contain all information required, to synthesize progeny phase Particle.