nucleicos

Nucleic acids are biopolymers that store, transmit, and participate in the expression of genetic information in all living organisms. The two main classes are deoxyribonucleic acid (DNA) and ribonucleic acid (RNA).

They are polymers of nucleotides, each consisting of a sugar, a phosphate group, and a nitrogenous base. In DNA the sugar is deoxyribose and the bases are adenine, thymine, cytosine, and guanine; in RNA the sugar is ribose and the bases are adenine, uracil, cytosine, and guanine. Nucleotides link by phosphodiester bonds to form a sugar–phosphate backbone, with the bases projecting inward.

DNA typically forms a double helix with two antiparallel strands. It stores genetic information in the sequence of bases and replicates semi-conservatively via DNA polymerases. RNA is usually single-stranded and more structurally diverse; it is synthesized by RNA polymerases during transcription and functions in protein synthesis and regulation. Major RNA classes include messenger RNA (mRNA), transfer RNA (tRNA), ribosomal RNA (rRNA), and regulatory small RNAs.

The central roles of nucleic acids include transcription of DNA into RNA and translation of RNA into proteins, bridging genotype and phenotype. In addition to coding functions, many RNA molecules regulate gene expression and catalyze biological reactions. Nucleic acids are present in all cellular life and in many viruses; DNA is generally the long-term storage form, with RNA acting as an information carrier and effector molecule.

Chemical properties contribute to stability: DNA is typically more chemically stable under cellular conditions, while RNA is prone to hydrolysis due to its 2'-hydroxyl group. The study of nucleic acids underpins genetics, molecular biology, medicine, and biotechnology.