Mitochondria
Mitochondria (singular- Mitochondrion) are membrane bound organelles, that carry out oxidative phosphorylation, to produce ATP. What is more, mitochondria produce the majority of ATP used by eukaryotic organisms and are often referred to as the power houses of the cell. Furthermore, due to the fact that mitochondria are the site ATP synthesis, there is often a linear relationship between the number of mitochondria in a cell and the cells ATP requirements e.g. a muscle cell uses vast amounts of ATP and thus often contains many mitochondria to adhere to this requirement and maintain function. A further point that must be brought to attention is that mitochondria contain there own DNA (mostly circular), referred to as mDNA. The size of mitochondrial DNA varies between species. Human mitochondrial DNA consists of 16,569 base pairs coding for 13 proteins. Mitochondria are semiautonomous organelles, depending on the host cell for their existence[1].
Structure
Mitochondria:
- Range from 0.5-1μm in diameter (similar to bacteria).
- Contain an inner (folds in) and outer membrane.
- Contain cristae (singular crista) - internal compartments formed by the inner membrane folds.
- Contain a matrix- large overall internal compartment.
In sexual reproduction only the female gamete (ovum) has mitochondria when the gametes eventually fertilise, this is because the male gamete (sperm) draws upon all of its mitohondria for locomotion, to aid its travel to the ovum (egg). Furthermore, mitochondria in relation to the structure of the sperm, is wrapped tightly around the flagellum in the sperm and is fixed in this position, to enable the mitochondira to comply with the sperm's unusually high ATP consumption [2].
