Final answer:
Complex I, Complex III, and Complex IV are located in the inner membrane of the mitochondria. They contain a series of electron carriers (co-factors) that are involved in the electron transport chain.
Step-by-step explanation:
Complex I, also known as NADH-coenzyme Q oxidoreductase or NADH dehydrogenase, is located in the inner membrane of the mitochondria. It is composed of flavin mononucleotide (FMN) and an iron-sulfur (Fe-S)-containing protein. Complex I pumps four hydrogen ions across the membrane from the matrix into the intermembrane space.
Complex III, also called cytochrome oxidoreductase, is another complex located in the inner membrane. It is composed of cytochrome b and c proteins and uses the energy of electrons obtained from coenzyme-Q (Q) to transport a hydrogen ion from the matrix to the intermembrane space.
Complex IV, also known as cytochrome c oxidase, is the final complex in the electron transport chain. It reduces oxygen into water and pumps four hydrogen ions from the matrix to the intermembrane space.