The synthesis of polysaccharides, proteins and nucleic acids requires an input of energy. Synthesis of each kind of biological polymer involves the loss of water in a condensation reaction. Not shown is the consumption of high-energy nucleoside triphosphates that is required to activate each subunit prior to its addition. In contrast, the reverse reaction--the breakdown of all three types of polymers--occurs by the simple addition of water (hydrolysis).  Fair Use and Copyright info