Ans. is 'b' i.e., 9 o One N ADH produces 2.5 ATP and one FADH2 produces 1.5 ATP. Thus 3 NADH and 1 FADH2 will produce 9 ATP.o There is production of ATP at substrate level also. Thus total 10 ATP molecules are produced per cycle.Energetics of TCA cycles iKreb's cycle)o One turn of the TCA cycle, starting with acetyl CoA produces 10 ATPs. When the starting molecule is pyruvate, the oxidative decarboxylation of pyruvate, the oxidative decarboxylation of pyruvate yields 2[?]5 ATPs and therefore, 12[?]5 ATPs are produced when starting compound is pyruvate. Since, two molecules of pyruvate enter the TCA cycle when glucose is metabolized (glycolysis produces 2 molecules of pyruvate), the number of ATPs is doubled. Therefore, 25 ATP molecules, per glucose molecule, are produced when pyruvate enters the TCA cycle,o Note : Previously calculations were made assuming that NADH produces 3 ATPs and FADH generates 2 ATPs. This will amount a net generation of 30 ATP molecules in TCA per molecule glucose and total 38 molecules from starting. Recent experiments shoiv that these values are overestimates and NADH produces 2[?]5 ATPs and FADH produces T5 ATPs. Therefore, net generation during TCA is 25 ATPs and complete oxidation of glucose through glycolysis plus citric acid cycle yield a net 32 ATPs.o Energy yield (number of ATP generated) per moleeule of glucose wrhen it is completely oxidized through glycolysis plus citric acid cycle, under aerobic conditions, is as follows :- Method ofATP formationNo of ATPs gained perglucose (new calculation)No of ATPs As per old calculationPathwayStepEnzymeSource Glycolysis1 Hexokinase.Minus 1Minus 1Do3Pbosphofructoki nase-Minus 1Minus 1Do5Glyceraldehyde-3-p DHNADHRespiratory chain2-5x2 = 53x2=6Do61,3-BPG kinaseATPSubstrate level1x2= 21x2=2Do9Pyruvate kinaseATPSubstrate level1x2= 21x2=2Pyruvate to-PyruvateNADHRespiratory chain2-5x2= 53x2=6Acetyl CoA Dehydrogenase TCA cycle3Isocitrate DHNADHRespiratory chain2-5x2= 53x2=6Do4Alpha keto giutarate DHNADHRespiratory chain2-5x2= 53x2=6Do5Succinate thiokinaseGTPSubstrate level1x2= 21x2=2Do6Succictnate DHFADH2Respiratory chain1-5x2= 32x2=4Do8Malate DHNADHRespiratory chain2-5x2= 53 x 2= 6Net generation in glycolytic pathway 9 minus 2=710 minus 2=8Generation in pyruvate dehydrogenase reaction=5 =6Generation in citric acid cycle=20 =24Net generation of ATP from one glucose mole=32 =38