what provides fuel for the cell
KEY ENERGY PROCESSES IN CELLS. Most of what a cell does involves endergonic reactions, requiring constant energy input; these reactions are coupled to just a few exergonic reactions which supply that energy. The key fuel source in cell reactions is Adenosine Triphosphate, or ATP. The molecule is an amino acid linked to a ribose sugar, linked to a string of three phosphate groups (there are also ADP, Adenosine Diphosphate, and AMP, Adenosine Monophosphate).