In geometry a double helix (plural helices) typically consists of two congruent helices with the same axis, differing by a translation along the axis, which may or may not be half-way.
The term "double helix" is commonly encountered in molecular biology, where it refers to the structure of DNA. The double-helix model of DNA structure was first published in the journal Nature by James D. Watson and Francis Crick in 1953, based upon the crucial X-ray diffraction image of DNA (labeled as "Photo 51") from Rosalind Franklin in 1952 , followed by her more clarified DNA image with Raymond Gosling, Maurice Wilkins, Alexander Stokes and Herbert Wilson, as well as base-pairing chemical and biochemical information by Erwin Chargaff.
Crick, Wilkins and Watson each received one third of the 1962 Nobel Prize in Physiology or Medicine for their contributions to the discovery. (Franklin, whose breakthrough X-ray diffraction data was used to formulate the DNA structure, died in 1958, and thus was ineligible to be nominated for a Nobel Prize.)
The DNA double helix is a right-handed spiral polymer of nucleic acids, held together by nucleotides which base pair together. A single turn of the helix constitutes ten nucleotides. The double helix structure of DNA contains a major groove and minor groove, the major groove being wider than the minor groove. Given the difference in widths of the major groove and minor groove, many proteins which bind to DNA do so through the wider major groove .
The order, or sequence, of the nucleotides in the double helix within a gene specifies the primary structure of a protein.
The term entered popular culture with the publication in 1968 of The Double Helix: A Personal Account of the Discovery of the Structure of DNA, by James Watson.