DNA Day celebration, not an annual holiday. Every year from 2003 onward, annual DNA Day celebrations have been organized by the National Human Genome Research Institute (NHGRI), starting as early as April 23 in 2010, April 15 in 2011 and April 20 in 2012. April 25 has since been declared "International DNA Day" and "World DNA Day" by several groups. DNA Day National DNA Day is a holiday celebrated on April 25. It commemorates the day in 1953 when James Watson, Francis Crick, Maurice Wilkins, Rosalind Franklin and colleagues published papers in the journal Nature on the structure of DNA. Furthermore, on
DNA corresponding X-ray diffraction and scattering patterns are characteristic of molecular paracrystals with a significant degree of disorder. Compared to B-DNA, the A-DNA form is a wider right-handed spiral, with a shallow, wide minor groove and a narrower, deeper major groove. The A form occurs under non-physiological conditions in partly dehydrated samples of DNA, while in the cell it may be produced in hybrid pairings of DNA and RNA strands, and in enzyme-DNA complexes. Segments of DNA where the bases have been chemically modified by methylation may undergo a larger change in conformation and adopt the Z form. Here, the strands