History of chemistry quantum mechanics were able to predict qualitatively some chemical features for biologically relevant molecules, they were, till the end of the 20th century, more a collection of rules, observations, and recipes than rigorous ab initio quantitative methods. This heuristic approach triumphed in 1953 when James Watson and Francis Crick deduced the double helical structure of DNA by constructing models constrained by and informed by the knowledge of the chemistry of the constituent parts and the X-ray diffraction patterns obtained by Rosalind Franklin. This discovery lead to an explosion of research into the biochemistry of life. In the same year, the
Rosalind Franklin and DNA and B forms of DNA were composed of two helical chains. By then, James Watson and Francis Crick at the Cambridge University had built a correct double helical model of DNA, based on her experimental data. The discovery of the structure of DNA in 1953 is regarded as "the greatest and most important scientific discovery of the 20th Century". Francis Crick, James Watson and Maurice Wilkins received the Nobel Prize in Physiology or Medicine in 1962 for the discovery. This discovery laid the foundation for modern biology, including medical and molecular researches. The discoverers earned a lasting worldwide fame. But