Nucleoside

Part of speech: noun

Pronunciation: /ˈn(j)u(ː)kliəˌsaɪd/

Definitions

1. A chemical entity consisting of a nitrogenous base linked to a sugar, which acts as a fundamental component of nucleic acids
2. An organic molecule that combines a sugar with a nitrogenous base, playing a key role in the structure of DNA and RNA
3. A biochemical compound formed by the union of a sugar and a nitrogenous base, serving essential functions in the formation of nucleic acids

Etymology: Nucleoside is a blend of two older chemical terms. The first half, "nucleo-", comes from "nucleus" and points to the nucleic acids, the molecules found in the nucleus of cells, which these compounds help build. The second half is "-oside", taken from "glycoside", a family of compounds in which a sugar is bonded to another molecule. A nucleoside is thus a sugar joined to a nitrogen-containing base, and the nucleotides that build DNA and RNA are made by adding a phosphate group to one. Chemists formed the word by clipping "glycoside" and attaching "nucleo-" to it, so the name describes the molecule's structure directly. The source for this etymology is probable rather than certain, which is why the pieces are best read as a description of what the compound is made of rather than a record of a single coining.

Synonyms: nucleotide, nucleic acid, DNA building block, RNA building block, sugar-base molecule