Bio 14 - 1 In 1928 Frederick Griffith sought to answer the...

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1) In 1928, Frederick Griffith sought to answer the question whether hereditary material was to be found in the protein histones or DNA of chromosomes. To do this, he infected mice with two different virulent strains of streptococcus pneumoniae, the normal one of these killed the mice. The mutant strain, which did not contain the usual polusaccharide coat, did not affect the mice at all. To then determine whether the coat was the cause of the illness, he injected the mice with a heat killed, coated bacteria. There was no effect. He then composed a mixture of the heat kill and the non-coated bacteria (the two compositions which did not kill the mice). This in fact killed the mice. Griffin then deduced that the bacteria were able to share certain information, in this case transferring of the polysaccharide coat to the living strain. In 1944, Avery, MacLeod, and McCarty helped to answer the question of where the hereditary information came from as they removed 99.8% of protein. The resulting arrangement had little effect as it resembled DNA in several ways. As far as the purified complex was chemically, at high speeds, after extracting lipids and proteins, and concering enzyme activity, it resembled DNA in all these ways. They therefore concluded that DNA was the principle transformer of pneumococcus and is the hereditary element. To support this claim, in 1952 Alfred Hershey and Martha chase experimented with bacteriophages, viruses that attack bacteria by injecting its DNA into the virus. Hershey
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Bio 14 - 1 In 1928 Frederick Griffith sought to answer the...

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