The Krebs Cycle is the central metabolic pathway in all aerobic organisms. The cycle is a series of eight reactions that occur in the mitochondrion. These reactions take a two carbon molecule (acetate) and completely oxidize it to carbon dioxide.
The cycle is summarized in the following chemical equation: acetyl CoA + 3 NAD + FAD + ADP + HPO4-2 ---------------> 2 CO2 + CoA + 3 NADH+ + FADH+ + ATP
Most summaries of the Krebs Cycle will usually indicate that the cycle is an aerobic process (one that requires oxygen) that produces ATP by breaking down glucose. A quick glance at the above equation will show you that no oxygen or glucose is used in the cycle and that it does not make much ATP (only one molecule for each acetyl CoA that enters the cycle).