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Griffith's Experiment

In 1928, Frederick Griffith conducted one of the first experiments to show that cells possessed genetic material

Griffith's experiment involved the use of two strains of pneumococcus – a deadly virulent strain (S) or a non-virulent strain (R)

When Griffith infected mice with the non-virulent bacteria (strain R), the mice survived.

When Griffith infected mice with the virulent bacteria (strain S), the mice died.

When Griffith infected mice with heat-killed virulent bacteria (strain R), the mice survived as the bacteria had been killed.

When Griffith infected mice with a mix of heat-killed strain S and living strain R, the mice were found to have died

From this Griffith’s concluded that the living R cells had somehow been transformed into virulent S cells

This indicated that there was some form of transferrable genetic material present within the cells (i.e. DNA)

Other conclusion: a chemical substance from one cell is genetically transforming another cell