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

Explanation

Hershey and Chase conducted experiments on bacteriophage to prove that DNA is the genetic material.

(i) Some bacteriophage virus were grown on a medium that contained radioactive phosphorus`(.^(32) P)` and some in another medium with radioactive sulphur `(.^(35)S)`.
(ii) Viruses grown in the presence of radioactive phosphorus `(.^(32)P)` contained radioactive DNA.
(iii) Similar viruses grown in presence of radioactive sulphur `(.^(35)S)` contained radioactive protein.
(iv) Both the radioactive virus types were to infect E. coil seperately .
(v) Soon after infection , the bacterial cells were gently agitated in blender to remove viral coats from the bacteria.
(vi) The culture was also centrifuged to separate the viral particle from the bacterial cell .
Observations and Conclusions
(i) Only radioactive `(.^(32)P)` was found to be associated with the bacterial cell, whereas radioactive `(.^(35)S)` was only found in surrounding medium and not in the bacerial cell.
(ii) This indicates that only DNA and not protein coat entered the bacterial cell.
(iii) This proves that DNA is the genatic material which is passed from virus to bacteria and not protein.
if both DNA and proteins contained phosphorus and sulphur, the resulat might change .In case
Radioactive `(.^(35)S)` and + Bacteriophage `(.^(32)P)` lsbelled protein capsule `to` No radioactive
`(.^(35)S)` and `(.^(32)P` Detected in cells + Radioactivity `(.^(35)S and .^(32)P)` detected in supernatant
In case(ii)
Radioactive `.^(35)S and .^(32)P `labelled DNA+ Bacteriophage `to` Radioactive `.^(32)Pand .^(35)S` Detected in cells + No radioactivity detected in supernatant