A nucleotide is a chemical compound that consists of a heterocyclic base, a sugar, and one or more phosphate groups. In the most common nucleotides the base is a derivative of purine or pyrimidine, and the sugar is the pentose (five-carbon sugar) deoxyribose or ribose.
Structure of a nucleotide
Nucleotides are the structural units of RNA, DNA, and several cofactors - CoA, FAD, FMN, NAD, and NADP. In the cell they play important roles in energy production, metabolism, and signaling.
Nucleotide names are abbreviated into standard three- or four-letter codes. The first letter is lower case and indicates whether the Nucleotide in question is a deoxyribonucleotide (denoted by a d) or a ribonucleotide (no letter). The second letter indicates the nucleoside corresponding to the nucleobase:
U: Uracil not present in DNA, but takes the place of Thymine in RNA
The third and fourth letters indicate the length of the attached phosphate chain (Mono-, Di-, Tri-) and the presence of a phosphate (P).
For example, deoxy-cytidine-triphosphate is abbreviated as dCTP.