Final answer:
Energy from NADH and FADH2 is used to pump H+ ions into the mitochondrial intermembrane space during electron transport in eukaryotes, where it facilitates the production of ATP via oxidative phosphorylation.
Step-by-step explanation:
During electron transport in eukaryotes, energy from NADH and FADH2 is used to pump H+ ions into the mitochondrial intermembrane space. The electron transport chain, located in the inner membrane of the mitochondrion, involves a series of electron carriers. As high-energy electrons from NADH and FADH2 are passed along this chain, they are transferred from molecule to molecule, which results in the release of energy.
This released energy is harnessed to actively transport protons (H+) across the envelope, from the mitochondrial matrix into the intermembrane space, creating an electrochemical gradient. This proton gradient is essential for the production of ATP during the process known as oxidative phosphorylation. Ultimately, the electrons from the electron transport chain combine with oxygen to form water, which occurs in the mitochondrial matrix.