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Experiments, Griffith concluded that hereditary materials had passed from…
Experiments
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Hersery-Chase
Alfred D.Hershey and Martha Chase performed several experiments using T2 bacteriophage, a virus that infects bacteria. Their results convinced even the sceptics that DNA, and not protein, was the genetic material
T2 bacteriophage infects Escherichia coli by injecting its DNA into the bacterium while leaving its protein coat on the outside. The viral DNA takes over the genetic machinery of the host cell to make new phages. Eventually, the bacterial cell lysed, releasing new phages to infect other bacteria
Hershey and Chase hypothesized that only the viral DNA entered the bacterium. They made use of the fact that viral DNA contains phosphorus but not Sulphur, whereas protein coat contains Sulphur but not phosphorus
They labelled the viral DNA in some T2 phages with a radioactive isotope of phosphorus (32P) and labeled the viral protein coat with a radioactive isotope of Sulphur (35P) in other T2 phages.
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Griffith concluded that hereditary materials had passed from dead bacteria to live bacteria. This changed the harmless strain R bacteria into virulent strain S pathogens. He called the process involved transformation and the hereditary material, the transforming agent. :
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