purine nucleobase metabolic process purine nucleobase biosynthetic process https://github.com/geneontology/go-ontology/issues/31634 purine base formation purine base synthesis purine base anabolism biological_process purine base biosynthesis GO:0009113 purine base biosynthetic process The chemical reactions and pathways resulting in the formation of purine nucleobases, one of the two classes of nitrogen-containing ring compounds found in DNA and RNA, which include adenine and guanine. nucleobase biosynthetic process purine-containing compound biosynthetic process