The mitochondrion is a membrane bound organelle found in most eukaryotic cells (the cells that make up plants, animals, fungi, and many other forms of life), which has the main function of aerobic respiration. The number of mitochondria in a cell can vary widely by organism, tissue, and cell type. For instance, red blood cells have no mitochondria, whereas liver cells can have more than 2000. The organelle is composed of compartments that carry out specialized functions. These compartments or regions include the outer membrane, the intermembrane space, the inner membrane, and the cristae and matrix.
A mitochondrion contains outer and inner membranes composed of phospholipid bilayers and proteins. The two membranes have different properties. Because of this double-membraned organization, there are five distinct parts to a mitochondrion. They are:
1. the outer mitochondrial membrane,
2. the intermembrane space (the space between the outer and inner membranes),
3. the inner mitochondrial membrane,
4. the cristae space (formed by infolding’s of the inner membrane), and
5. The matrix (space within the inner membrane).
Mitochondria stripped of their outer membrane are called mitoplasts.
Cristae: Shelf-like extensions of the inner membrane, some of which extend across the whole width of the mitochondrion, providing a large surface area for the attachment of enzymes involved in respiration.
Matrix: Makes up the remainder of the mitochondrion. It is a semi-rigid material containing protein, lipids and traces of DNA allowing the mitochondria to control the production of their own proteins.