You’ve already learned that, in addition to proceeding through glycolysis, glucose 6-phosphate (g6p) can be used to synthesize a carbohydrate storage molecule called glycogen. glucose 6-phosphate is also a precursor for the synthesis of nucleotides that are used to build dna and rna. the first step of this pathway is catalyzed by an enzyme called glucose 6-phosphate dehydrogenase. assume that reactions in this pathway with double arrows are reversible under cellular conditions, while those with single arrows are effectively irreversible.