Question

If the $DNA$ of a virus is labelled with ${}^{32}P$ and the protein of the virus is labelled with ${}^{35}S$, after transduction which molecule(s) would be present inside the bacterial cells?

• A. ${}^{32}P$ Only
• B. ${}^{35}S$ only
• C. Both (a) and (b)
• D. None of these

Answer 1

Answer: (A)

Bacteria which were infected with viruses that had radioactive $DNA$ (incorporated, with ${}^{32}P$) were radioactive, indicating that $DNA$ was the material that passed from the virus to the bacteria. Bacteria that were infected with viruses that had radioactive proteins (incorporated with ${}^{35}S$) were not radioactive. $DNA$ is therefore, the genetic material that is passed from virus to bacteria.