Exposing inner mitochondrial membranes to ultrasonic vibrations will disrupt the membranes. However, the fragments will reseal "inside out." These little vesicles that result can still transfer electrons from NADH to oxygen and synthesize ATP. If the membranes are agitated still further however, the ability to synthesize ATP is lost. After the first disruption, when electron transfer and ATP synthesize still occur, what must be present?

The inner mitochondrial membrane contains an electron transport chain and ATP synthesis. Four membrane protein complexes serve as the electron carriers and are embedded in the inner mitochondrial membrane. These protein complexes are called complex I, II, III and IV. Transfer of electrons from NADH and FADH2 to terminal electron acceptor oxygen occurs via these protein complexes.

During electron transfer, the pumping of protons towards the inner mitochondrial membrane creates an electrochemical gradient. The downhill transfer of protons back to the matrix via proton channel of ATP synthase drives phosphorylation of ADP. Therefore, presence of all the protein complexes of the electron transport chain and ATP synthase is required for electron transfer and ATP synthesis.