Mitochondria are small organelles distributed in varying numbers and patterns in the cytosol of most human cells. Mitochondria are enclosed by a double membrane, with the inner membrane folded into characteristic cristae. This creates multiple sub-compartments that harbor distinct functions and are essential to mitochondrial function. Mitochondria also possess a small independent genome, consisting of 37 genes. Mitochondria are responsible for cellular production of energy in the form of ATP, through the citric acid cycle and oxidative phosphorylation. This process occurs across the highly specialized inner mitochondrial membrane and the matrix within. Mitochondria are also involved in several other cellular processes, including oxidation of fatty acids, apoptosis, cell growth and cell cycle control, cell signaling and differentiation.
The amount and distribution of mitochondria varies with cell type. Typically, mitochondria are distributed in a thread-like pattern along microtubules, thus often extending from the perinuclear region to the edges of the cell. Sometimes, small rod-like entities can be distinguished.
Read more about the proteome of mitochondria.