AP BIOLOGY

Detailed explanation-1: -1930) In a very simple experiment, Oswald Avery’s group showed that DNA was the “transforming principle.” When isolated from one strain of bacteria, DNA was able to transform another strain and confer characteristics onto that second strain. DNA was carrying hereditary information.

Detailed explanation-2: -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-3: -In 1952, Alfred Hershey and Martha Chase took an effort to find the genetic material in organisms. Their experiments led to an unequivocal proof to DNA as genetic material. Bacteriophages (viruses that affect bacteria) were the key element for Hershey and Chase experiment.

Detailed explanation-4: -However, the most definitive proof that the transforming principle was DNA was its sensitivity to specific enzymes, called DNAses, that specifically degrade different kinds of DNA. Avery and his colleagues were able to show that transforming activity was not destroyed by enzymes that degrade proteins or RNA.