Question

Which of the following statements about the Hershey- Chase experiment are incorrect?
I: Bacteria infected with bacteriophage radiolabeled with ${}^{35}P$ were radioactive
II: Bacteria infected with bacteriophage radiolabeled with ${}^{35}S$ were radioactive
III: Bacteria infected with bacteriophage radiolabeled with ${}^{32}P$ were radioactive
IV: Bacteria infected with bacteriophage radiolabeled with ${}^{35}P$ and ${}^{32}S$ were radioactive
V: Bacteria infected with bacteriophage radiolabeled with ${}^{35}P$ were not radioactive

• A. Statements I, II, III are incorrect.
• B. Statements I, II, V are incorrect
• C. Statements I, II, IV are incorrect
• D. Statements II, III, IV are incorrect

Answer 1

The correct option is C Statements I, II, IV are incorrect

Alfred Hershey and M. Chase (1952), gave unequivocal proof that DNA is the genetic material.
In their experiment, radioactive phosphorus $\left({}^{32}P\right)$ and radioactive sulphur $\left({}^{35}S\right)$ were used to culture bacteriophages. The DNA of bacteriophage was radiolabeled with ${}^{32}P$ and protein with ${}^{35}S$.
These radiolabeled bacteriophages were then made to infect E. coli. It was seen that the bacterial cells contained radioactive viral DNA $\left({}^{32}P\right)$, but not radioactive viral protein (${}^{35}S$). This means that the bacteriophages transferred their DNA to the E. coli bacteria.
It can be concluded that the presence of radioactive ${}^{32}P$ in the bacteriophage enables the bacteria to become radioactive. As radioactive ${}^{32}P$ incorporated in the DNA of bacteriophage is passed down to the bacteria in the culture medium.
Thus, in the given question only statements III and V are correct, the rest are incorrect.