Discovery of DNA
Chargaff was an Austrian biochemist, he was best known for “Chargaff’s Rules” which lead to the discovery of DNA’s double helix structure. He immigrated to New York and secured a position as a research associate in the biochemistry department at Columbia University. Became a full-fledged professor in 1952. He used chromatographic techniques in his research.
It was in the U.S., 1950’s where he was able to make the crucial elements, in which lead to the formation of his rules; His discovery that thymine and adenine were equal in amount in DNA, and guanine and cytosine were also in equal amount to each other. (Known as the third Chargaff rule) With this knowledge and the help of two others more about DNA has been known because of Chargaff’s work.
In 1950 she became a research associate in the biophysics unit at King’s College, London. She was already skilled in techniques of crystallography and X-ray diffraction, because of time researching other carbon compounds at an institute in Paris. At King’s she improved the X-ray diffraction patterns so they made more detailed measurements than ever before (sharpest X-ray diffraction images of DNA in existence). In addition to this Franklin also produced high quality samples of DNA with the molecules aligned in narrow fibres. She done this and by careful control of humidity, two types of pure sample could be produced. She investigated both types, as she couldn’t be sure which was the normal structure. She held off publishing her results until she had strong evidence, she embarked on arduous analysis of the diffraction patterns, in order for her to calculate the dimensions of the DNA helix.
James Watson & Crick:
Watson was shown the best diffraction pattern and the calculations based on it that Franklin had figured out, however this was without her permission or even knowledge. From this Crick and Watson were able to build their model of DNA structure, and...
Bibliography: http://www.famousscientists.org/erwin-chargaff/ (01/02/2015)
Oxford IB Diploma programme, biology, 2014 edition (p.g. 107 & 345-347)
Please join StudyMode to read the full document