Give an account of Hershey and Chase experiment. What did it conclusively prove? If both DNA and proteins contained phosphorus and sulphur do you think the result would have been the same?

1. In the year 1952, Alfred Hershey and Martha Chase did an experiment to detect the presence of genetic material. For this experiment they took a virus called ‘Bacteriophage’.

2.The virus was grown in two separate mediums. One medium consisted radioactive phosphorus (P32). The other medium consisted of radioactive Sulphur (S35).

3.Medium containing radioactive Phosphorous had radioactive DNA because DNA is a phosphorus-basedstructure. Medium containing radioactive sulphur had radioactive protein.

4.Now, these viruses were injected into a bacterium called E. coli.

5.For this incorporation of Virus into E. coli, viral coats were removed by agitating them in the blender.

6.E. coli infected with virus had radioactive DNA and no radioactive proteins were present.

7.This showed that ‘DNA’ was the genetic material that got transferred from virus to E. coli and not protein.

CONCLUSION:

This experiment concluded, that DNA is the genetic material that transfers from one cell to another and not protein.

In such case,

a) Radioactive ³⁵ S and ³² p labelled protein capsule would show no radioactivity in the cell, but radioactivity would be detected in the supernatant.

b) Radioactive ³⁵ S and ³² p labelled DNA: Radioactivity is detected in the cells but not in the supernatant.

Such case would lead to non- conclusive experiment results.