Adenosine triphosphate, or ATP, is a molecule which acts as a universal energy currency for living cells. Its structure consists of the nucleoside adenosine and a tail of three phosphate groups.

During ATP synthesis via reactions or by ATP synthase energy is safely stored as chemical energy in the structure of ATP, specifically in the high energy phosphate bonds. The negative charges in the phosphate groups repel each other and need high amounts of energy to bond them together. When these high-energy bonds are broken, this energy is released through ATP hydrolysis.

ATP consists of adenosine and a three phosphate group tail. Adenosine consists of a hexagonal ring and a pentagonal ring that share one common side. Each ring consists of carbon, with 2 nitrogen in each ring. One carbon in the hexagonal ring has a bond to a nitrogen with 2 hydrogen protruding from the ring. A nitrogen in the pentagonal ring has a bond to a carbon atom in a ribose ring. The ribose ring is pentagonal, with four carbon atoms and one oxygen atom. Two carbon atoms in ribose have hydroxyl groups attached. The fourth carbon in ribose is bonded to an oxygen atom in a phosphate group. The phosphate group consists of a phosphorus atom with three single bonded oxygen atoms and one double bonded oxygen atom attached. Each of the three phosphate groups are attached to each other with a single bond to and oxygen on the adjacent phosphate group, forming a tail of phosphate groups.

Figure 1: Structure of ATP