Given that biological systems all exist in water, it is understandable that hydrolysis reactions are common in living organisms. Proteins are formed by linking amino acids together in long chains. These amino acids are linked by reacting a carboxylic group on one amino acid with an amine group on another with the generation of water in a process called condensation. The reverse process, hydrolysis, causes proteins to split up into their constituent amino acids. This is very useful in determining the structure of proteins in a process call amino acid analysis.