Which molecule is considered the main energy source for cells?

ATP, or adenosine triphosphate, is recognized as the primary energy currency for cells. This molecule stores and transports chemical energy within cells, facilitating various biochemical reactions essential for cellular functions. ATP consists of three phosphate groups, and when one of these phosphate bonds is hydrolyzed, it releases energy that cells can harness for processes such as muscle contraction, active transport across membranes, and biosynthetic reactions.

The high-energy phosphate bonds in ATP make it particularly well-suited for energy transfer. The molecule can quickly regenerate from ADP (adenosine diphosphate) and inorganic phosphate through cellular respiration processes, allowing cells to maintain a continual supply of energy. The other options, while involved in energy transfer or other cellular processes, do not serve as the primary energy source in the same efficient manner as ATP does.