How Is Cellular Energy Carried Between Coupled Reactions?
A. ATP is the Principal Energy Carrier in Cells 1. The most common energy-carrier molecule in cells is adenosine triphosphate (ATP) 2. ATP is the energy currency of living cells because it provides energy for a wide variety of endergonic reactions 3. Energy in ATP is carried in high-energy phosphate bonds; usually only the terminal phosphate bond is broken for energy release 4. ATP can be synthesized from adenosine diphosphate (ADP) and phosphate, using the energy released by exergonic reactions such as glucose breakdown (in-text art) 5. ATP can be broken down to ADP and phosphate to provide energy for endergonic reactions (in-text art) Web Tutorial 5.2: Energy and Life 6. Exergonic reactions of ATP precede endergonic reactions of muscle contraction (Figure 5-3) 7. Heat is given off during energy transfers involving ATP (Figure 5-4) 8. Life span of an ATP molecule is very short because it is constantly being formed and broken down B. Electron Carriers Also Transport Energy Within Cells
