Structure of ATP

Respiration exists, ultimately, to generate ATP (Adenosine Triphosphate), the molecule Karl Lohmann first discovered in 1929. Structurally, ATP is a nucleotide built from three parts: a nitrogenous base called adenine, a five-carbon sugar called ribose, and a chain of three phosphate groups attached in series to the sugar. The base and sugar together form adenosine, and adding one, two or three phosphate groups to adenosine gives adenosine monophosphate (AMP), adenosine diphosphate (ADP), and adenosine triphosphate (ATP) respectively. The bond linking the second and third phosphate groups is a high-energy bond, so when it is hydrolysed -- that is, when ATP loses its terminal phosphate to become ADP -- around 7.3 kilocalories (30.6 kJ) of usable energy is released per mole of ATP. Because ATP is present in every living cell and can be generated and spent almost instantly, it is called the universal energy currency of the cell, and the energy it releases powers the synthesis of carbohydrates, proteins and lipids among countless other cellular processes. Lipmann formally established this energy-transformation concept in 1941 …