Each of the three NADH molecules formed per turn of the cycle yields 3 ATPs and the one FADH2 yields 2 ATPs by oxidative phosphorylation (whereas some measurements indicate in which the quantities are 2.5 and 1.5 respectively - see p. 380). One GTP (or ATP) is synthesized straightly during the conversion of succinyl CoA to succinate. Thus the oxidation of a single molecule of glucose by the citric acid cycle produces 12 ATP molecules.