AP BIOLOGY

Detailed explanation-1: -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-2: -Frederick Griffith Discovers Bacterial Transformation et al. Studies on the chemical nature of the substance inducing transformation of pneumococcal types.

Detailed explanation-3: -Bacterial transformation is a process of horizontal gene transfer by which some bacteria take up foreign genetic material (naked DNA) from the environment. It was first reported in Streptococcus pneumoniae by Griffith in 1928. DNA as the transforming principle was demonstrated by Avery et al in 1944.

Detailed explanation-4: -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.