The energy source for the majority of cellular activities is adenosine triphosphate (ATP). ATP serves as the primary energy currency in cells, providing the necessary energy for various biochemical reactions essential for metabolism, movement, synthesis of biomolecules, and maintaining cellular structures. Cells generate ATP mainly through cellular respiration, a process that involves converting the energy stored in nutrients, particularly glucose, into ATP. This versatile molecule is crucial for sustaining life, enabling organisms to perform vital functions and respond to changes in their environment.