The organic molecule that serves as the primary energy source for all living cells is glucose. As a simple sugar, glucose plays a crucial role in cellular metabolism and energy production. It is primarily derived from the carbohydrates in our diet and is utilized by cells in various metabolic pathways, particularly during cellular respiration. By breaking down glucose, cells can generate ATP, the energy currency that fuels essential biological processes. Understanding glucose metabolism is key to areas like nutrition, physiology, and health.