Question

The result of the following reaction/experiment carried out by Avery et. al. on Streptococcus pneumonia has proved conclusively that DNA is the genetic material

• A. Live 'R' strain $+$ DNA from 'S' strain $+$ DNAase
• B. Heat killed 'R' strain $+$ DNA from 'S' strain $+$ DNAase
• C. Live 'R' strain $+$ DNA from 'S' strain $+$ RNAase
• D. Live 'R' strain $+$ Denaturated DNA of 'S' strain $+$ protease

Answer 1

The correct option is A Live 'R' strain $+$ DNA from 'S' strain $+$ DNAase

R-strain is rough and harmless, while S-strain is the smooth and virulent form of Streptococcuspneumoniae. In their experiment, Avery et al., found out that only when DNA from S-type bacteria is added to a culture of R-type bacteria, R-type gets converted to S-type strain. This transformation of R into S-type did not occur on addition of carbohydrate or protein from S-type bacteria. Moreover, in the first scenario, if DNase enzyme was added, i.e., Live 'R' strain + DNA from 'S' strain + DNase, the transformation would not have occurred, proving conclusively that DNA, indeed is the genetic material.

Thus, the correct answer is option A.