Provide a brief description of the process by which the body derives energy from food. Include in ...

In the first stage of catabolism, polymers are broken down into smaller subunits in the digestive system, which stretches from the mouth to the gut. Proteins are converted to amino acids, fats to fatty acids and glycerol, and carbohydrates simple sugars, including the monosaccharide glucose. In the second stage of catabolism, these simple subunits are further broken down to generate the activated carrier acetyl CoA. Acetyl CoA is the molecular input for the third stage of metabolism. In the last stage of catabolism, the acetyl CoA is oxidized to CO2, coupled to the production of large amounts of ATP, which is used as chemical energy for the cell.