Cells need a source of energy, they get this energy by breaking down food molecules to release, the stored chemical energy.This process is called 'cellular respiration'. The process is happens in all the cells in our body. Eukaryotic cells use three major processes to transform the energy held in the chemical bonds of food molecules into more readily usable forms — often energy-rich carrier molecules. Adenosine 5'-triphosphate, or ATP, is the most abundant energy carrier molecule in cells.
