A concentration gradient, a membrane protein, and hydrogen ions work together to provide a mitochondria with the energy needed to join small molecules together through ATP. The H+ ions are pumped across by membrane “pump proteins” into a space bounded by memb ranes that contain numerous amounts of hydrogen ions. Then, electrons are passed from o ne membrane-bound enzyme to another, which causes some energy to get lost during eac h transfer. This “lost energy” allows the pumping of hydrogen ions against the concentratio n gradient. After all the steps are taken, the mitochondrion will be provided with the energy needed to join small molecules together.