Question

The electron-transport system is grouped into three complexes that serve as proton pumps. The first complex is called the ___________ complex, the second complex is called the ___________ complex and the third complex is called the ___________ complex.

Answer 1

The first, second, and third complexes in the electron-transport system are the NADH dehydrogenase, succinate-Q reductase, and cytochrome oxidoreductase complexes, respectively. These complexes contribute to the proton gradient used for ATP synthesis, with complexes I and III serving as proton pumps along with complex IV.

Step-by-step explanation:

The first complex in the electron-transport system is called the NADH dehydrogenase complex, the second complex is called the succinate-Q reductase complex, and the third complex is called the cytochrome oxidoreductase complex. In the inner mitochondrial membrane, the electron transport chain consists of multiple copies of four protein complexes and two mobile accessory electron carriers, with complex I known as NADH dehydrogenase, complex II as succinate-Q reductase, and complex III as cytochrome oxidoreductase.

Complex I and III, along with complex IV (not requested in the student's question), function as proton pumps, transferring protons from the mitochondrial matrix to the intermembrane space, utilizing the energy released from electrons moving down the transport chain. Complex II, while part of the chain, does not pump protons.