Catabolic reactions are processes in which larger molecules are broken down into smaller ones, releasing energy in the process. These reactions are essential for providing the energy needed for various cellular activities. For example, the breakdown of glucose during cellular respiration is a common catabolic reaction that supplies energy to cells. In addition to glucose, catabolic reactions can involve fats and proteins, which are also broken down to release energy. This energy is often stored in the form of ATP (adenosine triphosphate), which cells use to power their functions. Overall, catabolic reactions play a crucial role in metabolism and energy production.