What did Hershey and Chase determine in their 1952 bacteriophage experiments about genetic material?

• A. Protein.
• B. Carbohydrates.
• C. Lipids.
• D. DNA, not protein, carries genetic information.

Answer: (D)

Genetic information is stored and transmitted by the molecule that actually directs the creation of new genetic material during replication. Hershey and Chase tested whether DNA or protein acted as this carrier in a virus that infects bacteria. They labeled DNA with radioactive phosphorus and protein with radioactive sulfur, then allowed the phages to infect bacteria. After infection, a blender separated the phage coats from the bacterial cells, and they checked where the radioactive signal ended up. The signal from the DNA label entered the cells and showed up in the newly formed phages, while the protein label stayed outside and did not drive production. This demonstrates that DNA carries the genetic instructions, not protein. The other molecules—carbohydrates or lipids—don’t match the evidence, and proteins were shown not to be the hereditary material in this experiment.