Different forms of the double helix: architecture and function Autors/ores Alexander Rich Resum The DNA double helix was discovered 50 years ago. This motif was found in several other places, most notably in RNA molecules. It is also found in DNA-RNA hybrids as well as transfer RNA molecules where double helical segments combine to form a more complex structure. A distinct variant of the DNA molecule was discovered in which the helix turns left-handed, which has led to practical consequences in the treatment of certain viral diseases. Since the molecule readily converted from A to B form, it clearly suggested that there was another form the double helix could adopt in the A form. Thus, the initial mystery why are there two such forms? It was known at the time that there are two major nucleic acids, one DNA and the other RNA, in which the sugar phosphate backbone contained ribose rather than the deoxyribose of DNA. One of the early questions that arose immediately after the Watson-Crick formulation was related to the nature of the RNA molecule-could it form a double helix? Descàrregues Text complet PDF (English) Publicat 2005-06-14 Número 2-4 Secció Focus Llicència This work, including photographs and other illustrations, unless the contrary is indicated, is subject to an Attributions–Non-Commercial–No Derivative Works 3.0 Creative Commons License, the full text of which can be consulted at http://creativecommons.org/licenses/by-nc-sa/3.0/. You are free to share, copy, distribute and transmit the work provided that the author is credited and reuse of the material is restricted to non-commercial purposes only and that no derivative works are created from the original material.