What is the last electron acceptor in the electron transport chain?

In cellular respiration, particularly during the process of oxidative phosphorylation, the last electron acceptor in the electron transport chain is oxygen. This step is crucial because it helps to maintain the flow of electrons through the chain, which is essential for the production of ATP, the energy currency of the cell.

As electrons are transferred through various protein complexes in the inner mitochondrial membrane, they ultimately pass to oxygen molecules. When oxygen receives these electrons, it combines with protons (hydrogen ions) to form water as a byproduct. This reaction is vital not only because it helps to drive the entire process of cellular respiration but also because the presence of oxygen allows for a higher yield of ATP compared to anaerobic respiration, where no electron transport chain or oxygen is involved.

In contrast, carbon dioxide, nitrogen, and hydrogen do not serve as terminal electron acceptors in the electron transport chain. Their roles in metabolism relate to different processes, such as carbon dioxide being a waste product of respiration and nitrogen being involved in amino acid synthesis rather than energy generation in this context. Hydrogen, while it is involved in creating a proton gradient, does not act as an electron acceptor at the end of the chain.