The Discovery Of DNA

The identification of a substance/phenomenon/condition(s) is the first step toward a new discovery or invention of substantial application (human or otherwise). In the light of this fact, the knowledge of the discovery of DNA is vital to appreciate the beauty of evolution of the events that led to the discovery of DNA. Unlike the common belief that DNA was discovered by the American biologist James Watson and English physicist Francis Crick, the genetic material was first identified by the Swiss physiological chemist Friedrich Miescher in the 1860s. He named them “nuclein”. While having an intention of separating and identifying the proteins present in the white blood cells, he discovered a material inside the white blood cells that were similar to proteins but having high phosphorus content. Sensing the importance of his findings, Miesher wrote “It seems probable to me that a whole family of such slightly varying phosphorous-containing substances will appear, as a group of nucleins, equivalent to proteins”. It was only in 1953, that Watson and Crick put together pieces of experimental information by various investigators to bring forth the three dimensional structure of DNA. Although, various improvisations and extensions have been brought forth to the Watson Crick model, but the four major propositions still remain the same :

• DNA is a double-stranded helix, with the two strands connected by hydrogen bonds. A base are always paired with Ts, and Cs are always paired with Gs, which is consistent with and accounts for ...

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..., with which the redox moiety collides with the electrode and transfers electrons [24]

• The G-rich and C-rich DNAs individually form the parallel G-quadruplex and I-motif, respectively, in the molecular crowding condition, and the 1:1 mixture folds into the parallel G-quadruplex and I-motif but does not form a duplex. The ITC measurements indicated that the thermodynamic stability (ΔG°20) of the duplex formation between the G-rich and C-rich DNAs in the noncrowding condition was −10.2 kcal mol-1, while only a small heat change was observed in the ITC measurements in the molecular crowding condition. These ITC results also demonstrated that the molecular crowding condition prevents any duplex formation between G-rich and C-rich DNAs. These results indicate that a structural polymorphism of the telomere DNAs is induced by molecular crowding in vivo [25]