Adn

ADN stands for ácido desoxirribonucleico (deoxyribonucleic acid), the molecule that stores genetic information in most living organisms and in some viruses. It contains the instructions necessary for growth, development, metabolism, and reproduction and is inherited from parents to offspring.

ADN is composed of two long chains of nucleotides coiled into a double helix. Each nucleotide contains a sugar molecule (deoxyribose), a phosphate group, and a nitrogenous base—adenine, thymine, cytosine, or guanine. The two strands run in opposite directions and pair A with T and C with G through hydrogen bonds, producing the characteristic base-pairing rules.

In eukaryotic cells, ADN is primarily located in the nucleus, with smaller amounts in mitochondria and chloroplasts. Prokaryotes lack a nucleus, and their ADN resides in the cytoplasm. DNA replication is semiconservative: the double helix unwinds, and each strand serves as a template for a new complementary strand, aided by enzymes such as helicase, DNA polymerase, primase, and ligase.

Genes encoded in ADN are transcribed into RNA and translated into proteins, following the central dogma. ADN is organized into chromatin by histone proteins in eukaryotes and exists as circular chromosomes in many prokaryotes; some organisms carry plasmids as well.

The double-helix model was proposed in 1953 by James Watson and Francis Crick, based on X-ray diffraction data from Rosalind Franklin and Maurice Wilkins. ADN is fundamental to biology, medicine, biotechnology, and forensic science, underpinning fields from genomics to gene therapy.