Mitochondria are cylindrical or sausage-shaped double membrane-bound organelles which are distributed in the cytoplasm. The outer and inner membranes are the two membranes that surround them.
A single circular DNA molecule, a few RNA molecules, 70S ribosomes, and the components needed to make proteins are all found in the mitochondrial matrix.
Due to their capacity for self-duplication through the presence of mtDNA, mitochondria are also referred to as semi-autonomous cell organelles.