Mitochondria are complex organelles that have a double membrane system, with the outer membrane being porous to allow for the passage of molecules. They contain their own DNA, which is important for the production of proteins needed for energy production. Mitochondria generate ATP through a series of biochemical reactions that occur in the electron transport chain. In addition to energy production, mitochondria also play a role in the regulation of cellular metabolism, calcium storage, and apoptosis. Dysfunction of mitochondria has been linked to a number of diseases, including diabetes, Parkinson’s disease, and Alzheimer's disease.