Mitochondria are integral to the metabolism of eukaryotic cells, yet many of their properties are not fully understood. In Part 1 of this iBioSeminar, Dr. Jared Rutter lays out the foundational knowledge of mitochondrial structure and origin, and shares what is currently known about mitochondrial roles in metabolism, protein homeostasis, and signaling. He ends by highlighting a focus of his research group: to unravel the functions of uncharacterized mitochondrial proteins.