Biochemical assay for transformation
Oswald Avery investigated the biochemical nature of Griffth's 'transforming principle'. He combined living R bacteria with heat-killed S material, and subjected the mixture to enzymes that selectively destroy protein, RNA, or DNA . Only the DNAse treatment destroys the capacity of S to transform R. This suggests that the transforming substance is DNA.
Homework: What is Avery's "Assay for Transformation"? How does it relate to the presence of R and S cells in the cultures on the third line above? How does this assay differ from Griffith's?