网页2021年1月20日 · Cytidine is a nucleoside consisting of cytosine and ribose sugar linked by β-N 1-glycosidic bond. When a phosphate group is covalently attached to the sugar, it forms a nucleotide. An example of a nucleotide wherein three phosphate groups are attached to cytidine is cytidine triphosphate (CTP), one of the building blocks of RNA synthesis.