Source of energy in kerb cycle is

ATP Generating Steps in TCA Cycle - There are 3 NADH molecules generated during one cycle, each of them will give rise to 2 1/2 ATPs on oxidation by electron transpo chain (ETC); so altogether they will give 3 x 2 1/2 = 7 1/2 (7.5) high energy phosphates. The FADH2 will generate 1 1/2 molecules of ATP. In addition, one molecule of GTP (equivalent to one molecule of ATP) is formed by substrate level phosphorylation. Hence, per turn of the cycle, 10 high energy phosphates are produced. STEP NO. REACTIONS COENZYMES ATPs 3 Isocitrate - alpha ketoglutarate NADH 2.5 4 Alpha ketoglutarate - succinyl CoA NADH 2.5 5 Succinyl CoA - Succinate GTP GTP 1 6 Succinate - Fumarate FADH2 1.5 8 Malate - Oxaloacetate NADH 2.5 TOTAL = 10 REF :DM VASUDEVAN TEXTBOOK OF BIOCHEMISTRY, EIGHTHEDITION,PG.NO.,305,307.