Adenosine triphosphate

ATP (adenosine triphosphate) An adenine (purine base), ribose, and three phosphate units containing nucleoside triphosphate that (a) releases free energy when its phosphate bonds are hydrolyzed and (b) pro­duces adenosine diphosphate (ADP) and inorganic phosphorous. This energy is used to drive ENDER- gonic reactions in cells (chemical reactions that require energy input to begin). ATP is produced in the cristae of mitochondria and chloroplasts in plants. It is the driving force in muscle contraction and protein synthesis in animals. It is the major energy source within cells.