Structure of Mitochondria

The mitochondrion is bounded by two membrane, the outer membrane and the inner membrane. The space between the two membranes is called the outer chamber or inter-membrane space. It is filled with a watery fluid, and is 40-70A in width. The space bounded by the inner chamber is called inner chamber or inner membrane space. The inner membrane space is filled with a matrix which contains dense granules (300-500A), ribosome and mitochondria DNA. The granules consist of insoluble inorganic salts and are believed to be the binding sites of divalent ions like Mg++ and Ca++. In some cases they apparently contain polymers of sugars. The side of the inner membrane facing the matrix side is called the M-side, while the side facing the outer chamber is called the C-side. Two to six circular DNA molecules have been identified within mitochondria. These rings may either be in the open or inn the twisted configuration. They may be present free in the matrix or may be attached to the membrane. The enzymes of the Krebs cycle are located in the matrix.



The inner membrane is thrown up into a series of folds, called cristae mitochondriales, which project into the inner chamber. The cavity of the cristae is called the intercristae space, and is continuous with the intermembrane space.

According to earlier description the outer surface of outer membrane and the inner surface of the inner membrane were supposed to be covered with thousands of small particles. Those on the outer membrane were described as being stalk less and were called the subunits of Parson. The stalked inner membrane particles were called the subunits of Fernandez-Moran. In recent works only the stalked particles o the inner membrane are considered by to be involved in hydrogen transport.