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Miescher's Discovery
Swiss chemist Friedrich Miescher was the first to identify DNA, which he called NUCLEIN. He found nuclein inside the nuclei of human white blood cells, when he tried to isolate and characterize the protein components of leukocytes. The new substance had chemical properties unlike any protein, a much higher phosphorous content and resistance to proteolysis. -
Levene's Discovery
Phoebus Levene discovered the order of the 3 major components of a single nucleotide and the carbohydrate component of RNA and DNA. He correctly identified the way RNA and DNA molecules are put together. He spent years using hydrolysis to break down and analyze yeast nucleic acids. Then he proposed that nucleic acids were composed of a series of nucleotides and that each nucleotide was in turn composed of just 1 of 4 nitrogen-containing bases, a sugar molecule and a phosphate group. -
Chargaff's Discovery
Austrian biochemist Erwin Chargaff wanted to know if there were any differences in DNA among different species, so he developed a new paper chromatography method for separating and identifying small amounts of organic material. He found that the nucleotide composition of DNA varies among species and almost all DNA maintains certain properties, even as its composition varies (the amount of Adenine = the amount of Thymine, the amount of Guanine =the amount of Cytosine, A+G=C+T -> Chargaff's rule) -
Watson and Crick's Discovery
Watson and Crick proposed the three-dimensional, double-helical model for the structure of DNA. Using cardboard cutouts representing the individual chemical components of the four bases and other nucleotide subunits, they shifted molecules around on their desktops, as though putting together a puzzle. In their model the complementary bases fitted together perfectly (i.e., A with T and C with G), with each pair held together by hydrogen bonds, but the structure also reflected Chargaff's rule.
