macromolecule metabolic process multicellular organismal macromolecule 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. macromolecule metabolism organismal macromolecule metabolism biological_process GO:0044259 GO:0043170 GO:0043283 biopolymer metabolic process organic substance metabolic process