The first step of carbohydrate catabolism is glycolysis. this process converts the 6-carbon glucose molecule into two 3-carbon molecules of pyruvate. this series of chemical reactions takes place in the cytosol. the next step of carbohydrate catabolism takes place in the mitochondrion. with the of coenzyme a, the 3-carbon molecules are converted to . this is the entry point for the , a 6-step process that harvests the chemical energy stored in carbohydrates in the form of high-energy electrons. during the last step of carbohydrate catabolism, the high-energy electrons liberated during previous steps are shuttled to the , which is a series of enzymes embedded in the membrane of the . the chemical energy is used to generate from and inorganic phosphate.