Mitochondria

Mitochondria are found in a large majority of eukaryotic cells, with their main function being to produce ATP from gathering energy from the oxidation of food and to take up oxygen, giving energy to the cell for it to carry out its functions and activities.(Friedman J.R. and Nunnari, J (2014) ‘Mitochondrial form and function’. Nature (505), pp 335-343). Mitochondria have been essential for the development and evolution of animals, without them far less effective methods of making energy, such as anaerobic glycolysis, this releases only a small portion of the energy which glucose oxidation can yield.(Lewis, J., Alberts, B., Johnson, A. and Walter, P. (2007) Molecular biology of the cell. 5th edn. New York: Garland Publishing page 815). There is much debate as to how mitochondria came about, but the most widely accepted one is the endosymbiotic theory in which an ancestral eukaryotic cell engulfed a prokaryotic cell.

(Lewis, J., Alberts, B., Johnson, A. and Walter, P. (2007) Molecular biology of the cell. 5th edn. New York: Garland Publishing page 856). The structure and form of the mitochondria is highly important in its functions. The inner membrane is a mostly impermeable structure, however with a very high concentration of proteins, which are used in oxidative phosphorylation and transporting metabolite such as pyruvates and fatty acids. The high impermeability of the inner membrane to small molecules and the majority of ions is critical to maintaining the proton gradient that allows for oxidative phosphorylation. The outer membrane is different however because it contains proteins called porins which allow for the diffusion of molecules by forming small channels. (Cooper, G.M. and Hausman, R.E. (2009) The cell: A molecular approach. 5th edn. Washington, DC: Sinauer Associates Inc.,U.S. page