If the net energy change is positive (catabolic reactions release more energy than the anabolic reactions use), then the body stores the excess energy by building fat molecules for long-term storage. On the other hand, if the net energy change is negative (catabolic reactions release less energy than anabolic reactions use), the body uses stored energy to compensate for the deficiency of energy released by catabolism

Conversely, anabolic reactions use the energy produced by catabolic reactions to synthesize larger molecules from smaller ones, such as when the body forms proteins by stringing together amino acids. Because catabolic reactions produce energy and anabolic reactions use energy, ideally, energy usage would balance the energy produced.

metabolism — sum of all catabolic and anabolic reactions that take place in the body. net energy change — positive (catabolic reactions release more energy than the anabolic reactions use), then the body stores the excess energy by building fat molecules for long-term storage. catabolic reactions — reactions that break down larger molecules into their constituent parts. anabolic reactions — reactions that build smaller molecules into larger molecules.

Be able to describe the process by which polymers are broken down into monomers; describe the process by which monomers are combined into polymers; discuss the role of ATP in metabolism.