Introduction Mitochondria are often referred to as the powerhouses of the cell since they produce most of the adenosine triphosphate (ATP) that serves as the primary energy source to support cellular function. However, the contribution of mitochondrial metabolism to cellular function is not limited to the production of ATP. Mitochondrial metabolism is essential on many fronts including crucial anabolic and catabolic processes that provide diverse molecules and energy sources to support life. For example, mitochondria are home to several core metabolic pathways including the citric acid cycle (tricarboxylic acid cycle, Krebs cycle), oxidative phosphorylation, and the beta-oxidation pathway for fatty acid degradation. The metabolic pathways of amino acids are also largely associated with mitochondria. In addition, mitochondria generate reactive oxygen species and are involved in the initiation and regulation of apoptosis (programmed cell death).