Mitochondrial Genome

The mitochondria (singular: mitochondrion) are enclosed by two membranes, each a phospholipid bilayer with a unique collection of embedded proteins. The outer membrane is smooth, but the inner membrane contains extensive folds called cristae. The cristae provide a means of packing a relatively large amount of the inner membrane into a very small container, thus enhancing the productivity of cellular respiration. The number of mitochondria per cell is correlated with the cell's level of metabolic activity, with a typical cell containing hundreds to thousands of these organelles. Time-lapse photography of living cells reveals mitochondria as very dynamic structures, moving around, changing shape, and dividing.

Often described as the "power plant" of the cell, mitochondria generate ATP by extracting energy from sugar, fats, and other fuels with the help of oxygen. Mitochondria generate most of the energy in animal cells through a process called oxidative phosphorylation. In this process, electrons are passed along a series of protein complexes that are located in the inner mitochondrial membrane. The passage of electrons between these protein complexes releases energy that is stored in the membrane, and is then used to make ATP from ADP.