double helix: Definition from Answers.com

For other meanings of double helix, see Double helix (disambiguation).

A staircase in the shape of a double helix, in the Vatican Museum

Image of a DNA chain which shows the double helix replicating itself

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.^[1]

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^[2], based upon the crucial X-ray diffraction image of DNA (labeled as "Photo 51") from Rosalind Franklin in 1952 ^[3], followed by her more clarified DNA image with Raymond Gosling^[4]^[5], Maurice Wilkins, Alexander Stokes and Herbert Wilson^[6], as well as base-pairing chemical and biochemical information by Erwin Chargaff^[7]^[8]^[9]^[10]^[11]^[12].

Crick, Wilkins and Watson each received one third of the 1962 Nobel Prize in Physiology or Medicine for their contributions to the discovery^[13]. (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^[14]. A single turn of the helix constitutes ten nucleotides^[14]. The double helix structure of DNA contains a major groove and minor groove, the major groove being wider than the minor groove^[14]. 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 ^[15].

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 his book: The Double Helix: A Personal Account of the Discovery of the Structure of DNA, by James Watson.

References

^ "Double Helix" by Sándor Kabai, The Wolfram Demonstrations Project, 2007.
^ James D. Watson and Francis Crick (1953). "A structure for deoxyribose nucleic acid". Nature 171: 737–8. doi:10.1038/171737a0. http://www.nature.com/nature/dna50/watsoncrick.pdf.
^ http://www.pbs.org/wgbh/nova/photo51/
^ http://www.nature.com/nature/dna50/franklingosling.pdf
^ The Structure of the DNA Molecule
^ Wilkins M.H.F., A.R. Stokes A.R. & Wilson, H.R. (1953). "Molecular Structure of Deoxypentose Nucleic Acids" (PDF). Nature 171: 738–740. doi:10.1038/171738a0. PMID 13054693. http://www.nature.com/nature/dna50/wilkins.pdf.
^ Elson D, Chargaff E (1952). "On the deoxyribonucleic acid content of sea urchin gametes". Experientia 8 (4): 143-145.
^ Chargaff E, Lipshitz R, Green C (1952). "Composition of the deoxypentose nucleic acids of four genera of sea-urchin". J Biol Chem 195 (1): 155-160. PMID 14938364.
^ Chargaff E, Lipshitz R, Green C, Hodes ME (1951). "The composition of the deoxyribonucleic acid of salmon sperm". J Biol Chem 192 (1): 223-230. PMID 14917668.
^ Chargaff E (1951). "Some recent studies on the composition and structure of nucleic acids". J Cell Physiol Suppl 38 (Suppl).
^ Magasanik B, Vischer E, Doniger R, Elson D, Chargaff E (1950). "The separation and estimation of ribonucleotides in minute quantities". J Biol Chem 186 (1): 37-50. PMID 14778802.
^ Chargaff E (1950). "Chemical specificity of nucleic acids and mechanism of their enzymatic degradation". Experientia 6 (6): 201-209.
^ "Nobel Prize - List of All Nobel Laureates". http://nobelprize.org/nobel_prizes/lists/all/.
^ ^a ^b ^c Alberts et al. (1994). The Molecular Biology of the Cell. New York: Garland Science. ISBN 978-0815341055.
^ Pabo C, Sauer R (1984). "Protein-DNA recognition". Annu Rev Biochem 53: 293–321. doi:10.1146/annurev.bi.53.070184.001453. PMID 6236744.

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	duplex deoxyribonucleic acid (cell and molecular biology)
	helicase
	globular deoxyribonucleic acid (cell and molecular biology)

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double helix

See also

References