Mitochondria are the primary consumers of oxygen in a cell and contain a multitude of redox carriers that are capable of transferring single electrons to oxygen. This results in the formation of the reactive oxygen species (ROS) superoxide. Mitochondria also contain an extensive antioxidant defense system to detoxify ROS, which would otherwise cause oxidative damage to cellular components. Thus, in structurally and functionally intact mitochondria, there is little net ROS production. Mitochondrial dysfunction occurs when the ROS-mediated oxidative stress overpowers the antioxidant defense system. The factors for triggering oxidative stress can be genetic defects, environmental factors like radiation and toxins and metabolic fluctuations. Neurodegenerative disorders, diabetes and cardiac ischemia are disease conditions that are associated with mitochondrial dysfunction.