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Definição e significado de Double-helix

Definição

double helix (n.)

1.a pair of parallel helices intertwined about a common axis"the shape of the DNA molecule is a double helix"

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Dicionario analógico

double helix (n.)


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Double-Helix

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Double helix

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

See also

References

  1. ^ "Double Helix" by Sándor Kabai, The Wolfram Demonstrations Project, 2007.
  2. ^ 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. 
  3. ^ http://www.pbs.org/wgbh/nova/photo51/
  4. ^ http://www.nature.com/nature/dna50/franklingosling.pdf
  5. ^ The Structure of the DNA Molecule
  6. ^ 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. 
  7. ^ Elson D, Chargaff E (1952). [Expression error: Missing operand for > "On the deoxyribonucleic acid content of sea urchin gametes"]. Experientia 8 (4): 143–145. 
  8. ^ Chargaff E, Lipshitz R, Green C (1952). [Expression error: Missing operand for > "Composition of the deoxypentose nucleic acids of four genera of sea-urchin"]. J Biol Chem 195 (1): 155–160. PMID 14938364. 
  9. ^ Chargaff E, Lipshitz R, Green C, Hodes ME (1951). [Expression error: Missing operand for > "The composition of the deoxyribonucleic acid of salmon sperm"]. J Biol Chem 192 (1): 223–230. PMID 14917668. 
  10. ^ Chargaff E (1951). [Expression error: Missing operand for > "Some recent studies on the composition and structure of nucleic acids"]. J Cell Physiol Suppl 38 (Suppl). 
  11. ^ Magasanik B, Vischer E, Doniger R, Elson D, Chargaff E (1950). [Expression error: Missing operand for > "The separation and estimation of ribonucleotides in minute quantities"]. J Biol Chem 186 (1): 37–50. PMID 14778802. 
  12. ^ Chargaff E (1950). [Expression error: Missing operand for > "Chemical specificity of nucleic acids and mechanism of their enzymatic degradation"]. Experientia 6 (6): 201–209. 
  13. ^ "Nobel Prize - List of All Nobel Laureates". http://nobelprize.org/nobel_prizes/lists/all/. 
  14. ^ a b c Alberts et al. (1994). The Molecular Biology of the Cell. New York: Garland Science. ISBN 978-0815341055. 
  15. ^ Pabo C, Sauer R (1984). [Expression error: Missing operand for > "Protein-DNA recognition"]. Annu Rev Biochem 53: 293–321. doi:10.1146/annurev.bi.53.070184.001453. PMID 6236744. 

 

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