Glucose is the primary fuel for cellular respiration. Through the process of cellular respiration, sugars are broken down into CO2 and H2O to make ATP that can be used to perform cellular work.
Cellular respiration occurs aerobically to yield about 38 ATP molecules for every one glucose molecule. Aerobic respiration consists of four stages: glycolysis, a transition reaction, the Krebs cycle and the electron transport chain.
Glycolysis occurs in the cytoplasm, and it breaks one molecule of glucose to two molecules of pyruvate. In the transition reaction, pyruvate is transported to the mitochondria and converted into acetyl-CoA. The Krebs cycle then strips pairs of hydrogen from acetyl-CoA in the mitochondrial matrix. In the final step, hydrogens carried by NADH are passed down the electron transport chain in the mitochondrial christae to produce ATP.