The main types of biochemical reactions are reduction and oxidation, water addition and removal, bond breaking reactions and the movement of groups between molecules. There are many possible types of biochemical reactions, but they all belong to one of those four categories.
Oxidation is when a substance gains oxygen, while reduction is when a substance loses oxygen. These types of reactions are essential for many types of life. Microorganisms living deep underground, for example, use the process of oxidation to create energy from their immediate environment.
Inside large molecules, there are smaller sub-groups of molecules. These groups can sometimes be moved between molecules to create new substances. This movement of groups is the basis for a number of different types of biochemical reactions.
Bond-breaking reactions are also essential for creating energy. Bonds between atoms and molecules contain energy, which can be released and harnessed if the bonds are broken and then remade.
While there are only four main types of biochemical reactions, this does not mean that the chemistry of life is not complex. Each type of reaction can take place in a number of different situations, which allows for a range of chemical processes from the same basic principles.