Citric Acid cycle
The pyruvate produced by glycolysis enters the mitochondria and is converted to two aceytl-CoA. Then the citric acid cycle occurs twice for each acetly-coa. in the critic acid cycle a two carbon molecule is attached to a four carbon molecule creating a six carbon molecule. As the six carbon compound travels the cycle two carbons are removed and released as carbon dioxide. This produces one ATP and three NADH. The molecule is now four carbon again and is recycled for the next aceytl-coa.