The mitochondrial inner membrane forms internal compartments known as crista

Crista

Cristae are the internal compartments formed by the inner membrane of a mitochondrion. They are studded with proteins, including ATP synthase and a variety of cytochromes. The maximum surface for chemical reactions to occur is within the mitochondria...

e, which allow greater space for the proteins such as cytochrome

Cytochrome

Cytochromes are, in general, membrane-bound hemoproteins that contain heme groups and carry out electron transport.They are found either as monomeric proteins or as subunits of bigger enzymatic complexes that catalyze redox reactions....

s to function properly and efficiently. The electron transport chain

Electron transport chain

An electron transport chain couples electron transfer between an electron donor and an electron acceptor with the transfer of H+ ions across a membrane. The resulting electrochemical proton gradient is used to generate chemical energy in the form of adenosine triphosphate...

 is located on the inner membrane of the mitochondria. Within the inner mitochondrial membrane are also transport protein

Transport protein

A membrane transport protein is a membrane protein involved in the movement of ions, small molecules, or macromolecules, such as another protein across a biological membrane. Transport proteins are integral membrane proteins; that is they exist within and span the membrane across which they...

s that transport in a highly controlled manner metabolites across this membrane.

The inner membrane of mitochondria (IMM) is similar in lipid composition to the membrane of bacteria

Bacteria

Bacteria are a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria have a wide range of shapes, ranging from spheres to rods and spirals...

. This phenomenon can be explained by the endosymbiont hypothesis of the origin of mitochondria as prokaryotes internalized by a eukaryotic host cell.

External links

• http://opm.phar.umich.edu/localization.php?localization=Mitochondrial%20inner%20membrane
• http://www.med.uiuc.edu/histo/small/atlas/objects/1340.htm