AP BIOLOGY

Detailed explanation-1: -Conclusion: Based on the observation, Griffith concluded that R strain bacteria had been transformed by S strain bacteria. The R strain inherited some ‘transforming principle’ from the heat-killed S strain bacteria which made them virulent. And he assumed this transforming principle as genetic material.

Detailed explanation-2: -In 1928, British bacteriologist Frederick Griffith conducted a series of experiments using Streptococcus pneumoniae bacteria and mice. Griffith wasn’t trying to identify the genetic material, but rather, trying to develop a vaccine against pneumonia.

Detailed explanation-3: -In this experiment, Griffith mixed the living non-virulent bacteria with a heat inactivated virulent form. He subsequently infected mice with this mixture and much to his surprise, the mice developed pneumonia and died. Furthermore, he was able to isolate colonies of the virulent strain from these mice.

Detailed explanation-4: -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.