Nucleotide
The monomer of nucleic acids, consisting of a nitrogenous base, a five-carbon sugar and a phosphate group.
Unit
Dimensionless
In depth
Nucleotides link through phosphodiester bonds between the 3′ hydroxyl of one sugar and the 5′ phosphate of the next, giving the chain a direction. Beyond their role in nucleic acids, nucleotides serve as energy carriers and signalling molecules.
Examples in the real world
Adenosine triphosphate as the cell's energy currency; cyclic AMP as a second messenger.