Question

Which radioactive isotope was used to label the protein coat in Set B of the Hershey-Chase experiment?

Options

• ⁷Be (Beryllium-7)

• ³⁵S (Sulphur-35)

• ³²P (Phosphorus-32)

• ¹⁴C (Carbon-14)

Answer 1

³⁵S (Sulphur-35) was used to label the protein coat because sulphur is found in amino acids (cysteine and methionine) and is absent from DNA. Bacteriophages grown in medium containing ³⁵S incorporated the isotope into their protein coats, creating radioactively labeled protein phages.