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Period: to
DNA Discoveries from 1900 through 1960
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P. A. Levene
Worked to determine the basic stucture of nucleotides, the chemicals that build up DNA. He also determined a difference between DNA and RNA. -
Fredrick Griffith
Griffith created an experiment that tested how different types of bacteria reacted when presented to mice. It also showed that certain types of bacteria were transformed into the other type. -
Oswald Avery
Did follow-up experiments on Griffith's tests, isolated different macromolecules such as DNA, lipids, and proteins. He determined that DNA was what transformed the bacteria. -
Maurice Wilkins
Wilkins worked at King's College in London, England. He also used X-rays to take photographs of DNA, trying to determine its shape. -
Erwin Chargaff
Found out that the chemicals adenine, guanine, thymine, and cytosine are what make up the "rungs" of tha DNA, as if it were a ladder. He also determined an two equations, C=G and T=A, showing the amount of cytosine was equal to the amount of guanine, and the amount of thynine was equal to the amount of adenine. -
Rosalind Franklin
Franklin had joined Wilkin's team at King's College in 1951, and was the first person to capture a picture of DNA. She used the X-ray technique and produced an image showing that DNA was a double helix shape. -
Hershey and Chase
Confirmed that DNA was the transforming factor in Griffith's and Avery's experiments. Also marked a DNA molecule with a radioactive label, letting them be able to track it as it moved and transformed. -
Watson and Crick
James Watson and Francis Crick worked at Cambridge University in 1953. They worked together to build a model of DNA, identifying it as a double helix after Franklin's photograph. -
Linus Pauling
Pauling had made his own discoveries in chemistry and medicine, and not much in DNA. After hearing about Franklin's discovery of the double helix, Pauling wanted to conduct his own research, but was unable to obtain a copy of Franklin's photograph.
