metabolic process macromolecule metabolic process macromolecule metabolism GO:0034960 organismal macromolecule metabolism GO:0044259 multicellular organismal macromolecule metabolic process GO:0043283 biopolymer metabolic process The chemical reactions and pathways involving macromolecules, any molecule of high relative molecular mass, the structure of which essentially comprises the multiple repetition of units derived, actually or conceptually, from molecules of low relative molecular mass.