Which of the following statements about the chemiosmotic synthesis of ATP is correct? 1 The energy for production of ATP from ADP comes directly from a gradient of electrons across the inner mitochondrial membrane. 2 Oxygen participates directly in the reaction that makes ATP from ADP and P. 3 The chemiosmotic synthesis of ATP requires that the electron transport in the inner mitochondrial membrane be coupled to proton transport across the same membrane. 4 The chemiosmotic synthesis of ATP occurs only in eukaryotic cells, because it occurs in mitochondria. 5 Chemiosmotic ATP synthesis requires oxygen.
Which of the following statements about the chemiosmotic synthesis of ATP is correct? 1 The energy for production of ATP from ADP comes directly from a gradient of electrons across the inner mitochondrial membrane. 2 Oxygen participates directly in the reaction that makes ATP from ADP and P. 3 The chemiosmotic synthesis of ATP requires that the electron transport in the inner mitochondrial membrane be coupled to proton transport across the same membrane. 4 The chemiosmotic synthesis of ATP occurs only in eukaryotic cells, because it occurs in mitochondria. 5 Chemiosmotic ATP synthesis requires oxygen.
Answered
The correct statement is:
3. The chemiosmotic synthesis of ATP requires that the electron transport in the inner mitochondrial membrane be coupled to proton transport across the same membrane.
Explanation:
- Statement 1 (Incorrect): The energy for ATP production comes from a proton gradient (not an electron gradient) across the inner mitochondrial membrane. Electrons from NADH and FADH2_2 are passed through the electron transport chain, which pumps protons (H+^+) into the intermembrane space, creating the gradient.
- Statement 2 (Incorrect): Oxygen does not directly participate in ATP synthesis. Oxygen serves as the final electron acceptor in the electron transport chain, but it does not directly make ATP. It combines with electrons and protons to form water.
- Statement 3 (Correct): The proton gradient established by the electron transport chain is crucial for ATP synthesis. The flow of protons back into the mitochondrial matrix through ATP synthase (a process called chemiosmosis) drives the conversion of ADP and inorganic phosphate (P) into ATP.
- Statement 4 (Incorrect): Chemiosmotic ATP synthesis also occurs in prokaryotic cells, which do not have mitochondria but use their cell membrane to generate a proton gradient.
- Statement 5 (Incorrect): While oxygen is essential for the electron transport chain and the regeneration of NAD+^+ and FAD+^+, it is not directly involved in the ATP synthesis process itself. However, ATP synthesis depends on the proton gradient created by the electron transport chain, which requires oxygen.
BNO Team