kaksoiskierteessä

Kaksoiskierteessä is a Finnish term that translates to "in a double helix." It most commonly refers to the iconic structure of deoxyribonucleic acid, or DNA. The DNA double helix is a fundamental component of life, carrying the genetic instructions for the development, functioning, growth, and reproduction of all known organisms and many viruses.

The double helix structure was famously elucidated by James Watson and Francis Crick in 1953, building upon the work of Rosalind Franklin and Maurice Wilkins. This structure consists of two long strands of nucleotides that coil around each other. Each nucleotide is composed of a sugar molecule, a phosphate group, and a nitrogenous base. The bases are adenine (A), guanine (G), cytosine (C), and thymine (T). In the DNA double helix, adenine always pairs with thymine (A-T), and guanine always pairs with cytosine (G-C). These base pairings form the "rungs" of the DNA ladder, while the sugar and phosphate groups form the "sides" or backbone.

The antiparallel nature of the two strands is crucial. One strand runs in the 5' to 3' direction, while the other runs in the opposite 3' to 5' direction. This orientation is essential for the process of DNA replication, where the genetic information is copied, and for transcription, where DNA is used as a template to create RNA. The helical structure provides stability and compactness to the long DNA molecule.