Double helix
In
geometry a double helix 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.
In modern pop culture, the double helix shape is strongly associated with
DNA. That the double helix is the structure of DNA was 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 strands of the bases
guanine,
adenine,
thymine, and
cytosine,
covalently linked through
phosphodiester bonds.
Encyclopedia
In
geometry a
double helix 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.
In modern pop culture, the double helix shape is strongly associated with
DNA. That the double helix is the structure of DNA was 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 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
