AP BIOLOGY

Detailed explanation-1: -Transformation was first demonstrated in 1928 by British bacteriologist Frederick Griffith. In 1928, Frederick Griffith was credited with discovering transformation in Streptococcus pneumoniae.

Detailed explanation-2: -Frederick Griffith, (born October 3, 1877, Eccleston, Lancashire, England-died 1941, London), British bacteriologist whose 1928 experiment with bacterium was the first to reveal the “transforming principle, ” which led to the discovery that DNA acts as the carrier of genetic information.

Detailed explanation-3: -Experiment: Griffith injected both S and R strains to mice. The one which was infected with the S strain developed pneumonia and died while that infected with the R strain stayed alive. In the second stage, Griffith heat-killed the S strain bacteria and injected into mice, but the mice stayed alive.

Detailed explanation-4: -Griffith developed the concept of the transforming principle. The prinicple was able to transform a non-pathogenic bacteria into a pathogenic strain. Changing phenotype is one of the characteristics of the hereditary material. Griffith called the factor that changed the phenotype the tranforming principle.