Illustration showing damage to a mitochondrial membrane by lipid peroxidation (free radical-mediated damage). Mitochondria are organelles that produce energy, in the form of adenosine triphosphate (ATP), for a cell. They produce reactive oxygen species (ROS) as a byproduct of respiration that interact with lipids in the mitochondrial membrane setting off a chain reaction of oxidative damage. This leads to mitochondrial dysfunction, which has been associated with many human diseases including cancer, cardiovascular diseases, diabetes, and neurodegenerative diseases.