Mitochondria-related organelles (MRO) are intra-cellular organelles which function like mitochondria but differ in one or more key aspects. The MRO designation refers to three main types of organelles: mitochondria which produce H2, hydrogenosomes, or mitosomes. Key aspects in which MROs may differ from mitchondria found in humans may include lack of ATP production, production of H2 molecules, lack of an electron transport chain, and (commonly) lack of using O2 as the terminal electron acceptor.
Like mitochondria, MROs contain a double membrane; however, they commonly do not possess a genome though this is not universal. This poses a question of how and why these organelles have been maintained in the eukaryotic cell.
Some MROs, as mentioned, do produce ATP providing power to the host cell. Research has shown there is also a role for MROs in amino acid metabolism and lipid metabolism. Additionally, some research shows that these organelles have been retained due to their function in Fe-S cluster assembly.