Question

Part A: In Griffith’s experiment, he concluded that some material had been transferred from the heat-killed smooth strain to the rough, nonvirulent strain. Why do you think Griffith chose to call this material the “transforming principle”?

Part B: How did Oswald Avery and his team help to prove that it was DNA, not proteins, which was the “transforming principle” in Griffith’s experiment?

Answer 1

Answer:

Question 1 :

Scientist Griffin called this experiment as "Transforming Principle" because some substance from the dead smooth strain has transformed the live rough strain. Thereby the rough strain was able to synthesise polysaccharide capsules and became virulent.

Question 2 :

McCarty , Avery and MacLeod proved that the transforming material is actually make DNA.

They did biochemical test to eliminate RNA, DNA and proteins.

They added DNase, RNase and Protease into 3 separate test tubes and again performed the Griffin's Experiment.

They observed that Transformation didn't take place in the test tube containing DNase enzyme. But Transformation occured usually in the other 2 test tubes.

This is how they confirmed that DNA is the transforming material.