Question

How did Hershey and Chase prove that DNA is the genetic material?

Answer 1

• Hershey and Chase experimented on bacteriophage to prove that DNA is the genetic material.
• In their experiment, they used bacteriophage T_2, which attacks bacteria E. Coli.
• They made two different preparations, one containing S³⁵ in the protein coat and the other one with P³² in the DNA molecule.
• These radiolabeled phages containing S³⁵ and P³² were allowed to infect a culture of non- radiolabelled E. Coli. The infected bacterial cells were centrifuged and then analysed.
• The mixture was then agitated in a blender (Blending) to detach the empty viral protein coats from the surface of the bacteria.
• The radiolabeled S³⁵ was found in the supernatant, which contained the viral coat, and the radiolabeled P³² was found at the bottom of the centrifuge tube, which contained the infected bacterial cells.

Thus, they concluded that DNA, not protein, entered the bacterial cell.