Final answer:
Alfred Hershey and Martha Chase's experiments with bacteriophages demonstrated that DNA, and not proteins, is the genetic material responsible for the replication of these viruses in host bacteria. They used isotopes 32P and 35S to distinctly tag DNA and proteins, respectively, and found that only 32P entered the bacterial cells.
Step-by-step explanation:
The bacteriophages used in Alfred Hershey's and Martha Chase's experiments showed that DNA is the genetic material responsible for the production of new phage particles, not proteins. Hershey and Chase used radioactive isotopes, 32P to label DNA and 35S to label proteins, in their experiments. They discovered that after the phages infected the bacteria, only the radioactive phosphorus (32P), which had labeled the DNA, could be found inside the bacterial cells. Since phosphorous is a component of DNA but not present in proteins, this provided strong evidence that DNA was the material responsible for heredity.
The importance of using a bacteriophage in this experiment, as opposed to an animal virus, was because bacteriophages inject only their genetic material into the host cell. This characteristic allowed Hershey and Chase to clearly demonstrate which component of the phage (DNA or protein) entered the bacterial cells and was responsible for the production of new phages.