Final answer:
The final stage of cellular respiration is called the electron transport chain, during which energy from NADH and FADH₂ is transferred to ATP. The process involves pumping hydrogen ions across the inner membrane of the mitochondrion, creating a chemiosmotic gradient that allows the ions to flow back through ATP synthase and produce ATP. Oxygen is necessary for this process as it serves as the final electron acceptor.
Step-by-step explanation:
The final stage of cellular respiration is called the electron transport chain. In this stage, energy from NADH and FADH₂ is transferred to ATP.
The electron transport chain consists of four protein complexes that are embedded in the inner membrane of the mitochondrion.
As electrons are passed from one complex to another, their energy is used to pump hydrogen ions (H+) across the inner membrane, creating a greater concentration of the ions in the intermembrane space than in the matrix.
This creates a chemiosmotic gradient that causes the hydrogen ions to flow back across the membrane into the matrix through ATP synthase, a channel protein and enzyme that helps convert ADP and inorganic phosphate into ATP.
Oxygen is needed in this process as it acts as the final electron acceptor and combines with the spent electrons to form water. Without oxygen, this process cannot occur.