Learning Objectives Describe phosphate esters. Understand why phosphate esters are important in living cells. Just as carboxylic acids do, inorganic acids such as nitric acid (HNO 3 ), sulfuric acid (H 2 SO 4 ), and phosphoric acid (H 3 PO 4 ) also form esters. The esters of phosphoric acid are especially important in biochemistry. A phosphoric acid molecule can form a monoalkyl, a dialkyl, or a trialkyl ester by reaction with one, two, or three molecules of an alcohol. Esters of pyrophosphoric acid and triphosphoric acid are also important in biochemistry. Esters of these acids are present in every plant and animal cell. They are biochemical intermediates in the transformation of food into usable energy. The bonds between phosphate units in adenosine triphosphate (ATP) are called phosphoanhydride bonds . These are high-energy bonds that store energy from the metabolism of foods. Hydrolysis of ATP releases energy as it is needed for biochemical processes (for instance, for muscle contraction). Phosphate esters are also important structural constituents of phospholipids and nucleic acids. Nitroglycerin The explosive nitroglycerin (glyceryl trinitrate) is an ester formed from glycerol and nitric acid. It is used in medicine to relieve chest pain in heart disease. What compounds combine to form phosphate esters? Answer phosphoric acids and alcohols Summary Esters of Phosphoric Acids and Their Importance in Biochemistry Phosphate Esters : Formation : Phosphoric acid (H₃PO₄) can react with one, two, or three molecules of an alcohol to form monoalkyl, dialkyl, or trialkyl esters, respectively 1 . Types : Esters of pyrophosphoric acid and triphosphoric acid are also significant in biochemistry 1 . Biochemical Importance : Energy Storage and Transfer : Adenosine Triphosphate (ATP) : The bonds between phosphate units in ATP are called phosphoanhydride bonds, which are high-energy bonds storing energy from food metabolism 1 . Hydrolysis of ATP releases energy necessary for biochemical processes like muscle contraction 2 . Structural Components : Phospholipids : Phosphate esters are crucial structural constituents of phospholipids, which form the bilayer of cell membranes 2 . Nucleic Acids : They are also integral to the structure of nucleic acids (DNA and RNA), playing a key role in genetic information storage and transfer 2 . Metabolic Intermediates : Biochemical Intermediates : Phosphate esters act as intermediates in the transformation of food into usable energy within cells 3 . These roles underscore the essential nature of phosphate esters in maintaining cellular functions and overall biochemical processes 1 2 3 .