Bioinorganic chemistry studies the role of metals in biology. It also studies natural phenomena such as the behaviour of metalloproteins and artificially introduced metals in medicine and toxicology. Many biological processes such as respiration depend on some inorganic molecules. Bioinorganic chemistry also includes the study of inorganic models or mimics that imitate the way metalloproteins work. It is a mix of biochemistry and inorganic chemistry. Bioinorganic chemistry studies the implications for biology of electron-transfer proteins, substrate bindings and activation, atom and group chemistry as well as metal properties.