nucleic acids, ribonucleic acid (RNA) and deoxyribonucleic acid (DNA), the sequence of nucleotides in the DNA or RNA codes for the structure of proteins synthesized in the cell. The nucleotide adenosine triphosphate (ATP) supplies the driving force of many metabolic processes. Several nucleotides are coenzymes; they act with enzymes to speed up (catalyze) biochemical reactions.

Nucleosides are similar to nucleotides except that they lack the phosphate group. Nucleosides themselves rarely participate in cell metabolism.

Adenosine monophosphate (AMP) is one of the components of RNA and also the organic component of the energy-carrying molecule ATP. In certain vital metabolic processes, AMP combines with inorganic phosphate to form ADP (adenosine diphosphate) and then ATP. The breaking of the phosphate bonds in ATP releases great amounts of energy that are consumed in driving chemical reactions or contracting muscle fibres.