Definition (Mitochondria): These are slender microscopic filaments or rods found in the cytoplasm.
Shape: Rod shaped, filamentous, spherical.
Size: 0.1-0.5 µm in diameter with 10 µm in length.
Structure: They are bounded by the external and internal membranes. The internal membrane projects folds into the interior of the mitochondria. These are called cristae. Thus two spaces are defined:
- Outer space: Between the two membranes called the intracristal space.
- Inner space: Within the internal membrane, penetrated by cristae. This space is filled with granular matrix.
- It is the chief source of energy. So it is called the powerhouse of the cell.
- It is concerned with the synthesis of RNA and protein because it contains DNA.