Figure 1.

Schematic structure of a mitochondrion. Mitochondria are surrounded by two membranes defining the intermembrane space and the matrix. The inner membrane is highly folded to increase surface area and forms cristae. Complexes of the electron transport chain (ETC) are located here. Both mitochondrial membranes have a high number of transport proteins, e.g., TIM (inner membrane translocase) and TOM (outer membrane translocase). Among other things, the matrix contains mitochondrial DNA (mtDNA), ribosomes, and granules.