In chemiosmosis, what is the most direct source of energy that is used to convert ADP + i to ATP?
A) energy released as electrons flow through the electron transport chain
B) energy released from substrate-level phosphorylation
C) energy released from movement of protons through ATP synthase, down their electrochemical gradient
D) energy released as electrons are transported across the inner mitochondrial membrane

Question

In chemiosmosis, what is the most direct source of energy that is used to convert ADP +  i to ATP?
A) energy released as electrons flow through the electron transport chain 
B) energy released from substrate-level phosphorylation 
C) energy released from movement of protons through ATP synthase, down their electrochemical gradient 
D) energy released as electrons are transported across the inner mitochondrial membrane

Quizplus · Accepted Answer

The movement of protons through ATP synthase, down their electrochemical gradient, is the most direct source of energy that is used to convert ADP + Pi to ATP in chemiosmosis. This is because the energy released from the movement of protons is coupled with the synthesis of ATP from ADP and Pi by ATP synthase, which is an enzyme that functions as a molecular motor. The other options are not direct sources of energy for ATP synthesis in chemiosmosis. Energy released as electrons flow through the electron transport chain and as electrons are transported across the inner mitochondrial membrane ultimately contribute to the proton gradient that drives the synthesis of ATP, but they are not the most direct sources of energy. Energy released from substrate-level phosphorylation is used to synthesize ATP outside of the electron transport chain and is not directly coupled with the proton gradient.

In Chemiosmosis, What Is the Most Direct Source of Energy