Question

D 18) How did Avery, MacLeod, and McCarty demonstrate that Griffith's transforming principle was DNA? A) Injecting live S-strain bacteria alone could not kill a mouse. B) Injecting heat-killed S-strain bacterial alone could not kill a mouse. C) Heat-killed S-strain bacterial transformed live R-strain bacteria into live S-strain bacteria. D) DNase, an enzyme that destroys DNA, eliminated the biological activity of the transforming material. E) RNase, an enzyme that destroys RNA, had no effect on the transforming principle.

Answer 1

D ) DNase , an enzyme that destroys DNA , eliminated the biological activity of the transforming material.

S strain was used and incoporated into different tube containing different enzyme.

1 tube ( S strain + protease ) = mouse die

2 tube ( S strain + RNase )=mouse die

3 tube ( S strain + DNase )= mouse alive

because the transforming material is degraded by the DNase and allow the mouse to survive . This show that the transforming material is DNA and not protein.