Identify the element used by Hershey and Chase to label the protein in their experiment, from the following options :

The correct option is S³⁵.

Step-by-Step Explanation:

1. Background of the Hershey-Chase Experiment (1952):
Alfred Hershey and Martha Chase conducted experiments to determine whether DNA or protein was the genetic material that viruses (bacteriophages) inject into bacteria to direct the synthesis of new virus particles.

2. Composition of DNA and Proteins:
To distinguish between the virus's DNA and its protein coat, they took advantage of the unique chemical elements found in each molecule:
• Proteins contain sulfur ($S$) but do not contain phosphorus ($P$).
• DNA contains phosphorus ($P$) but does not contain sulfur ($S$).

3. Radioactive Labeling:
• To label the protein coat, Hershey and Chase grew one batch of bacteriophages in a medium containing radioactive sulfur-35 ($S^{35}$). Since sulfur is present in amino acids like cysteine and methionine (which make up proteins), the radioactive sulfur incorporated exclusively into the viral proteins.
• To label the DNA, they grew another batch of bacteriophages in a medium containing radioactive phosphorus-32 ($P^{32}$), which incorporated exclusively into the viral DNA.

4. Conclusion:
Therefore, the radioactive isotope used specifically to label the protein in the Hershey-Chase experiment is sulfur-35 ($S^{35}$ or S³⁵).