DNA: stuff of life
The chemical
For many years, people who studied genetics thought that DNA wasn't complex enough to contain all of the information needed to make up a genome. However, an elegant experiment carried out by Alfred Hershey and Martha Chase in 1952 began to convince scientists that DNA carried the genetic information, rather than protein.
The Hershey-Chase experiment
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In this experiment, Hershey and Chase used a bacterial virus called T2. Although they are only made up of a shred of DNA and a scrap of protein, these viruses can hijack bacterial cells to make more copies of themselves. Scientists knew that either DNA or protein must carry the instructions for making new viruses, but they didn't know which. When Hershey and Chase added a radioactive label to the DNA of the original virus, they found that the viruses produced were also radioactive. The researchers also labelled the protein of the original virus, but found that the viruses produced then were not radioactive. Hershey and Chase concluded that the DNA that carried the instructions to make new viruses, and that it was the DNA that was being passed on to subsequent generations. |
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