Describe and explain the mechanism behind the specificity of enzyme reactions.

An enzyme is a protein that catalyses a reaction. That means they perform the reaction without being used up. Enzymes are very specific. Typically only one enzyme with catalyse one kind of reaction. This is because of the 3D or 'Tertiary' shape. This shape is very specific and is analogous to being a 'Key in a Lock'. Hence the term the Lock and key mechanism. One key will only open one lock, much as one enzyme will only catalyse one reaction. This model has been researched further and there is a more advanced model know as the induced fit model which would make some great further reading!