In chemiosmotic phosphorylation, 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 system
B)energy released from substrate-level phosphorylation
C)energy released from movement of protons through ATP synthase, against the electrochemical gradient
D)energy released from movement of protons through ATP synthase, down the electrochemical gradient
E)No external source of energy is required because the reaction is exergonic.

Question

In chemiosmotic phosphorylation, 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 system 
B)energy released from substrate-level phosphorylation 
C)energy released from movement of protons through ATP synthase, against the electrochemical gradient 
D)energy released from movement of protons through ATP synthase, down the electrochemical gradient 
E)No external source of energy is required because the reaction is exergonic.

Quizplus · Accepted Answer

The most direct source of energy used to convert ADP to ATP in chemiosmotic phosphorylation is the movement of protons through ATP synthase, down the electrochemical gradient. This movement of protons is coupled with the synthesis of ATP from ADP and inorganic phosphate. The energy released from movement of protons down their electrochemical gradient is harnessed to drive the rotation of the ATP synthase rotor, which allows the catalytic subunits to synthesize ATP from ADP and inorganic phosphate. Energy released as electrons flow through the electron transport system and energy released from substrate-level phosphorylation are not directly used to drive the synthesis of ATP in chemiosmotic phosphorylation.

In Chemiosmotic Phosphorylation, What Is the Most Direct Source of Energy