Question

(a) Describe the various steps of Griffith’s experiment that led to the conclusion of the ‘Transforming principle’.(b) How did the chemical nature of the ‘Transforming principle’ get established ?

Answer 1

a. Streptococcus pneumonia

S -stain ‘inject into mice’ mice die.

R - strain ‘inject into mice’ mice alive.

S - strain ‘inject into mice’ mice alive.

R - strain + S strain ‘inject into mice’ mice die.

R strain transformed into virulent.

b. Purified biochemicals from heat killed S - strain.

Treated with protease - did not affect transformation.

Treated with RNase - did not affect transformation.

Treated with DNase - transformation affected.