The cornerstone of cellular respiration is the process of glycolysis, which occurs in the cytoplasm of cells. During glycolysis, glucose is broken down into two molecules of pyruvate, yielding a small amount of ATP and electron carriers like NADH. This process is essential for converting the energy stored in glucose into a form usable by cells. Following glycolysis, aerobic respiration continues in the mitochondria, involving the citric acid cycle and the electron transport chain, ultimately leading to the production of a significant amount of ATP. These processes are fundamental for maintaining the energy requirements of living organisms.