In Hershey and Chase experiment, some viruses grew on medium that contained:
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → 35S, 32P
Hershey and Chase wanted to know whether the protein or the DNA of a bacteriophage enters the bacterium. They labelled the two with different radioactive isotopes. Protein contains sulphur but DNA does not; DNA contains phosphorus but protein does not.
Option (1) 35S, 32P — Correct. 35S labelled the protein coat of one set of viruses and 32P labelled the DNA of the other set. Only the 32P went into the bacteria, which showed that DNA is the genetic material.
Option (2) 36S, 34P — Incorrect. These are not the radioactive isotopes used in the experiment.
Option (3) 32S, 36P — Incorrect. 32S is the common, non-radioactive form of sulphur, so it could not label anything. 36P was not used either.
Option (4) 34S, 36P — Incorrect. Neither of these was used. The labels were 35S and 32P.
NCERT Extract:
The Genetic Material Is DNA – “… Hershey and Chase worked to discover whether it was protein or DNA from the viruses that entered the bacteria. They grew some viruses on a medium that contained radioactive phosphorus and some others on medium that contained radioactive sulfur. Viruses grown in the presence of radioactive phosphorus contained radioactive DNA but not radioactive protein because DNA contains phosphorus but protein does not. Similarly, viruses grown on radioactive sulfur contained radioactive protein but not radioactive DNA because DNA does not contain sulfur.”