what causes hydrogen to pass through atp synthase why is oxygen important for this process?
The correct answer and explanation is:
Answer:
Hydrogen ions (protons) pass through ATP synthase because of a proton gradient across the inner mitochondrial membrane. This gradient is created by the electron transport chain pumping protons from the mitochondrial matrix into the intermembrane space. Oxygen is essential as the final electron acceptor in the electron transport chain, allowing the chain to continue functioning and maintain the proton gradient.
Explanation (300 words):
ATP synthase is a vital enzyme embedded in the inner membrane of mitochondria that produces ATP, the energy currency of the cell. The driving force behind ATP synthesis is the flow of hydrogen ions (protons) through ATP synthase, a process known as chemiosmosis.
During cellular respiration, the electron transport chain (ETC) uses energy released from electrons transferred through a series of protein complexes to pump protons from the mitochondrial matrix into the intermembrane space. This pumping action creates a high concentration of protons outside the matrix and a low concentration inside, forming an electrochemical gradient called the proton motive force.
Hydrogen ions naturally want to move back into the matrix to equalize this gradient, but the inner mitochondrial membrane is impermeable to protons. ATP synthase provides a channel that allows protons to flow down their gradient, from the intermembrane space back into the matrix. As protons flow through ATP synthase, this movement causes conformational changes in the enzyme, driving the phosphorylation of ADP to ATP.
Oxygen’s role is critical because it acts as the final electron acceptor in the electron transport chain. After electrons pass through the ETC complexes, they combine with oxygen and protons to form water. Without oxygen to accept electrons, the ETC would become “backed up,” stopping electron flow. This cessation would halt proton pumping, collapsing the proton gradient necessary for protons to pass through ATP synthase. In other words, oxygen keeps the ETC running, maintaining the proton gradient that powers ATP production.
In summary, hydrogen ions pass through ATP synthase due to the proton gradient created by the ETC. Oxygen is essential to sustain this gradient by accepting electrons and allowing continuous proton pumping, enabling efficient ATP synthesis during aerobic respiration.