Double helix

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

The blue strand is one helix, and the red strand is another, together they form a double helix

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.

In modern popular 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, based on work by Rosalind Franklin. The double helix shape is very strong. DNA takes this shape over a straight shape naturally for two reasons. It must be 'double' so it can reproduce itself and the helix, being intertwined, is stronger than two parallel chains because pulling it in any one direction won't break it apart.

See also

• Nucleic acid
• Molecular structure of Nucleic Acids