Avery and McCarthy Experiment on Genetic Material, DNA is Genetic Material, Ribonuclease Enzyme, Dnase Enzyme, Enzymatic Treatment

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	Avery and McCarthy Experiment on Genetic Material - These experiments provided the first evidence that DNA was the genetic material. Avery and his associates prepared the filtrate from the heat killed smooth strain of S. pneumoniae and then subjected it to specific degradation enzymes separately.
The filtrate was divided into 3 parts, first part was exposed to protease enzyme which degrades protein, second part was exposed to ribonuclease enzyme which degrades the RNA and the last part was exposed to DNase enzyme which degrades DNA. After enzymatic treatment, the filtrate was tested for retention of its transforming ability. Surprisingly protease and RNases treatment had no effect on the transforming activity. However, digestion of the DNA with deoxyribonuclease totally destroyed the transforming ability, that the filtrate was not able to transform R type to S type. Gradually it became clear to Avery and her scolleagues that the genetic material is DNA and not protein.
To confirm further, McCarthy isolated DNA from S-type cells of pneumonia and purified it by using electrophoresis and ultracentrifugation. Then by using direct physical and chemical analyses she showed the transformation substance to be DNA. Unfortunately, these findings did not establish the fact that DNA is genetic material. Most biologists believed that protein contamination in the preparation is responsible for transformation.