Cellular energy transfer refers to the process by which cells convert and utilize energy to perform various functions. This process primarily involves the molecule adenosine triphosphate (ATP), which acts as the main energy currency of the cell. Cells generate ATP through cellular respiration, where glucose and oxygen are used to produce energy, carbon dioxide, and water. In addition to ATP, cells also use other molecules like NADH and FADH2 to store and transfer energy. These molecules play crucial roles in metabolic pathways, including the Krebs cycle and electron transport chain, ensuring that energy is efficiently produced and utilized for cellular activities.