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Friedrich Miescher
Miescher discovered that nuclein (DNA) was composed of hydrogen, oxygen. nitrogen, and phosphorus. He discovered this while examining used bandages that contained pus. This proved that all living organisms are composed of DNA. -
Erwin Chargaff
Chargaff discovered the "Chargaff rules", which state that the number of adenine and thymine are almost always equal, as well as the amounts of guanine and cytosine. He mad his discovery by separating purines and pyrimidines using chromatography paper. He then held each component under ultraviolet light. When each component absorbed a different characteristic of the light, he was able to tell the amount of which bases were present in DNA -
Rosalind Franklin
Franklin made her discovery after taking two high resolution pictures of crystallized DNA fibers, one more highly hydrated than the other. From this she found the basic dimensions of DNA strands, as well as the phosphates were found on the outside of a helical structure. These findings ,along with Watson and Crick, went on to prove the structure of DNA -
Hershey and Chase
Hershey and Chase discovered that DNA made up an organisms genetic material, not proteins. They discovered this while injecting DNA or protein into a host bacteria. Their discoveries proved that organism's genetic material was in DNA, not proteins. -
Watson and Crick
In 1953, Watson and Crick discovered the DNA double helix model. They made this discovery after acting on advice from Jerry Donohue, who stated the configuration of the rings in thymine and guanine given in most chemistry textbooks were incorrect. . After taking his advice, Watson moved the two bases to their correct places. It was then while moving more of the cardboard models that he not only proved the model of DNA, he also proved that Chargaff's rules had been true. -
Watson and Crick Continued
This disproved the transforming principle that many had previously believed. -
Meselson and Stahl
Meselson and Stahl discovered the semi-conservative model of DNA replication. They discovered this by conducting an experiment in which they grew the E.coli bacteria in 15N medium. The experiments proved that DNA replicated semi-conservatively. This showed how every DNA strand reproduced.
