Which experiment is associated with determining that DNA is the genetic material?

• A. Hershey and Chase
• B. Mendel
• C. Darwin
• D. Watson and Crick

Answer: (A)

The main idea tested is which molecule actually carries genetic information and directs the production of new organisms. Hershey and Chase showed that DNA, not protein, is the genetic material. They used bacteriophages labeled with radioactive atoms: one label on DNA (phosphorus-32) and another on protein (sulfur-35). When the phages infected bacteria, they used a blender to separate the phage coats from the bacterial cells and then checked where the radioactive signal ended up. The signal inside the bacteria came from the DNA label, not the protein label, meaning the genetic material that entered the cell and directed new phages was DNA. This provided clear evidence that DNA stores and transmits genetic information, not proteins.

This finding clarified a long-standing question about what encodes hereditary information, bridging earlier ideas from geneticists like Mendel, who described how traits are inherited, with later work that established the molecular basis of inheritance. It also sets the stage for understanding how DNA’s role relates to the structure Dawid Watson and Crick later described, while recognizing that Hershey and Chase’s experiment was the pivotal demonstration that DNA is the genetic material.