DNAkaksoiskierteiden

DNAkaksoiskierteiden, commonly known as the DNA double helix, is the molecular structure that carries most of the genetic instructions in all known living organisms. It consists of two long strands of nucleotides that coil around each other to form a helix. Each nucleotide is composed of a deoxyribose sugar, a phosphate group, and one of four nitrogenous bases: adenine (A), guanine (G), cytosine (C), and thymine (T). The two strands are held together by hydrogen bonds between the bases. Adenine always pairs with thymine (A-T), and guanine always pairs with cytosine (G-C). This specific pairing, known as complementary base pairing, is crucial for DNA replication and the accurate transmission of genetic information.

The structure was first proposed by James Watson and Francis Crick in 1953, based on X-ray diffraction data produced by Rosalind Franklin and Maurice Wilkins. This discovery revolutionized biology and medicine, paving the way for understanding heredity, genetic diseases, and the development of genetic engineering. The helical structure allows DNA to be compactly stored within cells and provides a mechanism for its replication. During replication, the two strands unwind, and each serves as a template for the synthesis of a new complementary strand, ensuring that daughter cells receive an identical copy of the genetic material. The sequence of bases along the DNA strand encodes the genetic information, dictating the production of proteins and other molecules essential for life.