The Citric Acid Cycle
	AKA the Tricarboxylic Acid (TCA) Cycle or the Krebs Cycle.

The Citric Acid Cycle is one of 3 stages of cellular respiration.  The others are glycolysis and electron transport/oxidative phosphorylation.

The big picture:  Glycolysis breaks 1 glucose into 2 pyruvate, producing 6 ATP.  Pyruvate is used to make acetyl-CoA, the starting product for the citric acid cycle.  Each turn of the cycle oxidizes 1 pyruvate, so it takes 2 turns to completely oxidize 1 glucose.  Two turns produce 8 NADH, 2 FADH2, and 2 ATP.  NADH and FADH2 are then oxidatively phosphorylated, resulting in 28 more ATP.  The 3 stages together produce 30 to 38 ATP.

The net reaction for the 8 proper steps of the cycle:

Acetyl-CoA + 3 NAD⁺ + FAD + GDP + P_i + 2H₂0  <==> CoASH + 3 NADH + FADH₂ + GTP + 2CO₂ + 3H⁺

DGº' =  -49  kJ/mol         DG ~  -115  kJ/mol

Click on a molecule to read more about it and to see it in Chime.

Tainted by Chemical X Heather Shepheard  UNT Chemistry Department

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