AP BIOLOGY

Detailed explanation-1: -His research career culminated in 1944, when, with McCarty and MacLeod, Avery published his seminal paper proving that the “transforming principle, ” or hereditary material, was DNA and not protein as most scientists had assumed.

Detailed explanation-2: -Avery and McCarty concluded that the transforming substance, which produced permanent, heritable change in an organism, was DNA.

Detailed explanation-3: -These results suggested that DNA was the molecule responsible for transformation. Avery and his colleagues provided further confirmation for this hypothesis by chemically isolating DNA from the cell extract and showing that it possessed the same transforming ability as the heat-treated extract.

Detailed explanation-4: -Avery and McCarty observed that proteases-enzymes that degrade proteins-did not destroy the transforming principle. Neither did lipases-enzymes that digest lipids. They found that the transforming substance was rich in nucleic acids, but Ribonuclease, which digests RNA, did not inactivate the substance.