Question

Give an account of the 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?

Answer 1

Hershey and Chase experiment:

In 1952 Alfred Hershey and Martha Chase conducted an experiment in which they infected Escherichia coli with T2 bacteriophage to prove that the genetic material is DNA and not proteins.

• The T2 bacteriophage is made up of DNA and protein coat. It infects the bacteria and multiplies inside it.
• DNA contains phosphorus and protein contains sulphur.
• Initially the phage was grown in a medium with radioactive phosphorus (32P), then it was grown in a medium with radioactive sulphur (35S).
• The phage DNA was incorporated with radioactive phosphorus and the phage protein was incorporated with radioactive sulphur.
• Then these labelled phages are allowed to infect bacteria grown in a normal medium.
• After the infection, the infected bacteria was broken down by blender and centrifuged.
• The bacterial cells showed the presence of radioactive phosphorus inside the cell and radioactive sulphur was present outside the cell.
• This shows DNA is the genetic material not protein.

$IfbothDNAandproteinscontainedsulphurandphosphorus:$

If both DNA and proteins contained sulphur and phosphorus, then it would have become difficult to interpret which biochemical material of virus is being transferred in the bacteria.

Thus, no, the result wouldn't be the same in this case.