Molecular Basis Of Inheritance Question 14

Question: From the experiments carried out by Avery, Macleod and McCarty by using various enzymes, which of the following results prominently proved that DNA is the transforming material?

Options:

A) DNA of heat killed ‘S’ + R type + DNAase $ \to $ virulent strain

B) DNA of heat killed ‘S’+R type + RNAase $ \to $ virulent strain

C) DNA of heat killed’ S’ + R type $ \to $ virulent strain

D) DNA of heat killed ‘S’+R type + Protease $ \to $ virulent strain

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Answer:

Correct Answer: C

Solution:

[a] Heat-killed S-type bacteria caused a transformation of the R-type bacteria into S-type bacteria but he was not able to understand the cause of this bacterial transformation.

The occurrence of living 19 S-type virulent bacteria is possible only by their formation from R-type non-virulent bacteria, which pick up the trait of virulence from dead bacteria.

This phenomenon is called Griffith effect or transformation.

Griffith proposed that a chemical substance released by heat killed bacteria changed the R-bacteria into S-bacteria which was a permanent genetic change.