Molecular models of DNA simulations that are very important to understand how DNA functions "in vivo". From the very early stages of structural studies of DNA by X-ray diffraction and biochemical means, molecular models such as the Watson-Crick nucleic acid double helix model were successfully employed to solve the 'puzzle' of DNA structure, and also find how the latter relates to its key functions in living cells. The first high quality X-ray diffraction patterns of A-DNA were reported by Rosalind Franklin and Raymond Gosling in 1953. Rosalind Franklin made the critical observation that DNA exists in two distinct forms, A and B, and produced
Z-DNA as a left-handed double helix with two antiparallel chains that were held together by Watson–Crick base pairs (see X-ray crystallography). It was solved by Andrew Wang, Alexander Rich, and coworkers in 1979 at MIT. The crystallisation of a B- to Z-DNA junction in 2005 provided a better understanding of the potential role Z-DNA plays in cells. Whenever a segment of Z-DNA forms, there must be B–Z junctions at its two ends, interfacing it to the B-form of DNA found in the rest of the genome. In 2007, the RNA version of Z-DNA, Z-RNA, was described as a transformed version of