Final answer:
Alfred Hershey and Martha Chase used bacteriophages labeled with radioactive isotopes to prove that DNA is the genetic material, by demonstrating that DNA enters a bacterial cell during infection, not protein.
Step-by-step explanation:
The question 'How did Hershey and Chase use microbes to prove that DNA is genetic material?' is addressing an important experiment in molecular biology conducted by Alfred Hershey and Martha Chase. This experiment used bacteriophages, which are viruses that infect bacteria, to demonstrate that DNA, and not protein, is the genetic material of the phage. By labeling the DNA with radioactive phosphorus (^32P) and the proteins with radioactive sulfur (^35S), they were able to track which of these molecules entered the bacterial cell during infection. After the phages had infected the bacteria, Hershey and Chase used a blender to separate the phage coats from the bacterial cells and then used a centrifuge to separate the mix into its components. They found radioactivity from phosphorus in the bacteria, confirming that it was the DNA that entered the cell and not the protein. This evidence was conclusive in proving that DNA is the molecule responsible for genetic heredity.