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.
Doppelhelix | 이중 나선 | Dubbele helix | 二重らせん | Podwójna helisa
This article is licensed under the GNU Free Documentation License.
It uses material from the
"Double helix".
Home Page • arts • business • computers • games • health • hospitals • home • kids & teens • news • physicians • recreation• reference • regional • science • shopping • society • sports • world