Enzymes are a type of protein, and like other proteins, they are made by the translation of the genetic code into a particular sequence of amino acids by ribosomes. After the enzyme is created as a chain of amino acids, it folds into a particular shape and often binds to other compounds, known as cofactors, before it becomes fully functional. Enzymes are crucial to the operation of cellular mechanisms.
Enzymes are biological catalysts, meaning that they encourage targeted chemical reactions without being consumed by them. When a cell needs two different compounds to react to form a new compound, and that reaction does not take place spontaneously in a cell's internal environment, it uses an enzyme. The enzyme is designed to react spontaneously with one of the targeted reactants. Unlike the targeted reactant alone, the compound formed by the reaction of the enzyme and the one reactant react spontaneously with the other reactant. Once this occurs, the enzyme changes to release the newly created target compound.
Enzymes are integral to all life. They are so universal that some scientists think they are actually the original biological molecules rather than DNA or RNA. They are created by the same machinery that creates structural proteins for stable and dynamic cellular structures but are used very differently.