Double helix
Encyclopedia : D : DO : DOU : Double helix
- For James D. Watson's book, see The Double Helix.
- Doublehelix is an Asterix character.
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 double helix is the structure of DNA as first published by James D. Watson and Francis Crick in 1953. They constructed a molecular model of DNA in which there were two complementary, antiparallel (side-by-side in opposite directions) strands of the bases guanine, adenine, thymine, and cytosine, covalently linked through phosphodiester bonds. The four nitrogen-containing bases found in DNA are divided into two groups: purines and pyrimidines. Two-ringed bases are purines. One-ringed bases are called pyrimidines. Adenine and Guanine are purines, whilst Thymine and Cytosine are Pyrimidines. Each strand forms a helix, and the two helices are held together through hydrogen bonds, ionic forces, hydrophobic interactions, and van der Waals forces forming a double helix.
See also
The Double Helix was also a popular breakfast cereal in the 80's. It consisted of bite-size pieces of flatbread coated in curdled milk.
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