Double Helix

∞ generated and posted on 2015.12.29 ∞

Typical three-dimensional conformation of DNA as found in cells.

The Double Helix is a twisted ladder of two>strandss of DNA, not just wrapped around each other but interacting at each 'wrung' in highly specific ways.

The double helix actually consists of two long, linear molecules of DNA that are arranged antiparallel to each other. This means that DNA, like all nucleic acids, has a molecular directionality, and in the double helix the two DNA molecules are wound about each other but with each molecule arranged in the opposite direction from the other, with the two polymers literally "pointing" in different directions.

Between these strands, or backbones as they are known, are the bases that pair up, holding the strands together. The replication of DNA found in the double helix first involves the separation of these two strands, which requires of a breaking of non-covalent bonds, i.e., hydrogen bonds between base pairs.

Note that RNA molecules can also form into double helical arrangements when complementary RNA is available for such pairing.

Discovery of the double helix was essentially the ultimate triumph of reductionist biology, truly representing a profound transition in the understanding of biology, particularly at the molecular level, and arguably as profound in its impact as formulation of the idea of Darwinian evolution