What does cytidine mean?
Cytidine is one of the four principal nucleosides that make up ribonucleic acid (RNA), alongside adenosine, guanosine, and uridine. Structurally, it consists of two parts joined by a chemical bond: cytosine, a flat ring-shaped molecule known as a nitrogenous base, and ribose, a five-carbon sugar. When a cell builds an RNA chain, cytidine units are incorporated in sequence, where their cytosine bases pair specifically with guanine on the complementary strand. Beyond its structural role, cytidine participates actively in metabolism: cells convert it into phosphorylated forms such as cytidine triphosphate (CTP), which supplies energy and raw material for synthesizing phospholipids and other essential molecules. The term appears almost exclusively in scientific contexts — biochemistry textbooks, research papers on antiviral drugs, and discussions of nucleotide metabolism — where precision about which molecular component is meant matters greatly. Its close relatives, differing only in sugar or base, form a family of compounds central to genetics and pharmacology.
nounA nucleoside consisting of the nitrogenous base cytosine linked to the sugar ribose; it is a fundamental structural component of RNA and a precursor in cellular metabolism.
- The nucleoside composed of cytosine attached to ribose, found in RNA.
- (Biochemistry) Any of its phosphorylated derivatives, such as cytidine monophosphate, diphosphate, or triphosphate, when referred to simply by this name.
"The enzyme converted cytidine into its monophosphate derivative as part of the salvage pathway."
"Supplementation studies examined whether oral cytidine could raise brain phosphatide levels."
"In the RNA sequence, each strand was built from alternating units of cytidine and uridine."
Rarely pluralized except when referring collectively to molecules of cytidine or to a set of cytidine-containing compounds.
"The polymer contained several consecutive cytidines near the termination signal."
Your cells recycle cytidine so efficiently that they can rebuild RNA building blocks from scraps — a molecular salvage operation running billions of times a day inside you.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of cytidine
The name cytidine derives from cytosine, the base it contains, whose own name traces to Greek 'kytos', meaning 'hollow vessel' or 'cell' — a reference coined in the late nineteenth century when the base was first isolated from cell tissue. The '-idine' ending follows a standard convention in organic chemistry for naming glycosides and related ring compounds. Cytidine itself was identified in the early twentieth century as chemists worked out the composition of yeast nucleic acid (RNA). Its name shares the '-idine' suffix with sibling nucleosides such as uridine and thymidine, all named after their constituent bases.
Related word forms
How cytidine is actually used
Strictly a technical term used in biochemistry, molecular biology, and medicine; rarely encountered outside scientific writing. In laboratory contexts, 'cytidine' sometimes refers loosely to phosphorylated forms of the molecule when the phosphate group's position is unspecified.
Easily confused with cytidine
Cytosine is the nitrogenous base alone, whereas cytidine is the nucleoside formed when cytosine is bonded to a ribose sugar.
Deoxycytidine contains deoxyribose rather than ribose and is a component of DNA, while cytidine contains ribose and occurs in RNA.