Further evidence that DNA was the genetic material came from studies that tracked the infection of bacteria by viruses. ○ Viruses consist of DNA (or sometimes RNA) enclosed in a protective coat of protein. o To replicate, a virus infects a host cell and takes over the cell’s metabolic machinery. o Viruses that specifically attack bacteria are called bacteriophages or just phages. In 1952, Alfred Hershey and Martha Chase showed that DNA was the genetic material of the phage T2. The T2 phage, consisting almost entirely of DNA and protein, attacks Escherichia coli ( E. coli ), a common intestinal bacteria of mammals. This phage can quickly turn an E. coli cell into a T2-producing factory that releases phages when the cell ruptures. To determine the source of genetic material in the phage, Hershey and Chase designed an experiment in which they could label protein and DNA and then track which entered the E. coli cell during infection. o
This is the end of the preview. Sign up
access the rest of the document.