Glucose catabolism, alternative routes

The major pathway of catabolism of monosaccharides, such as glucose and fructose, is glycolysis. Monosaccharides are converted into pyruvate with the generation of ATP [6]. Pyruvate is an intermediate in several metabolic pathways, but the majority of it is converted to acetyl coenzyme A, which enters the citric acid cycle. Although more ATP is generated in the citric acid cycle, the most important product is NADH, which is derived from NAD+ as the acetyl coenzyme A is oxidized. This oxidation releases carbon dioxide as a waste product. An alternative route for glucose catabolism is the pentose phosphate pathway, in which pentose sugars such as ribose is produced. 

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