Adenosince Triphosphate is broken down into one molecule of inorganic phosphate and a molecule of adenosine diphosphate, the energy released from this bond is captured and use to drive most cellular processes. some form of carbohydrate or triglyceride is used to generate the ATP in the first place depending upon a particular species and needs at the time
Mitochondria is the site of cellular respiration which produces energy. A cell with few energy needs would therefore contain a small number of this organelle.