The passage of electrons down the electron transport chain appears to provide the energy for the active transport of hydrogen ions across the membrane from the mitochondrial matrix. What is the purpose of transporting the transporting the hydrogen ions across the membrane?

The high concentration of positively charged hydrogen ions in this outer chamber causes the H+ ions to flow back into the mitochondrial matrix through an ATP synthase protein complex embedded in the inner mitochondrial membrane. The flow of H+ ions (protons) through this complex constitutes a proton-motive force that is used to drive ATP synthesis.

Short answer: to drive ATP synthesis from ADP

The purpose of transporting hydrogen ions across the membrane is to create a concentration gradient of hydrogen ions, also known as a proton gradient. This proton gradient is formed by pumping hydrogen ions from the mitochondrial matrix, which has a low concentration of hydrogen ions, to the intermembrane space, creating a high concentration of positively charged hydrogen ions in the outer chamber.

This high concentration of hydrogen ions in the intermembrane space causes the hydrogen ions to flow back into the mitochondrial matrix through an ATP synthase protein complex embedded in the inner mitochondrial membrane. This flow of hydrogen ions is driven by the proton gradient and is known as chemiosmosis.

The flow of hydrogen ions through the ATP synthase complex generates a proton-motive force. This force is used by the ATP synthase complex to convert ADP (adenosine diphosphate) into ATP (adenosine triphosphate) through a process called phosphorylation. ATP is the primary energy currency of cells, and it fuels various cellular processes.

In summary, by transporting hydrogen ions across the membrane, the electron transport chain creates a proton gradient that is used as a source of energy to drive ATP synthesis, ultimately providing the cell with the energy it needs to carry out its functions.