S14 - ATP Synthesis Mechanism

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Questions and Answers

What is the energy yield from the electron transport chain for 1 NADH?

2.5 ATP (correct)

4.5 ATP

3.5 ATP

1.5 ATP

The reaction ADP + Pi => ATP + H2O is irreversible in the enzyme surface.

False

What is the binding energy that drives the equilibrium toward the formation of ATP in the ATP synthase enzyme?

The binding energy of ATP synthase stabilized ATP relative to ADP + Pi by binding ATP more tightly (Kd 10^-12 : 10^-5)

The β subunits of ATP synthase are found in the _______________________ of ATP synthase.

head group Signup and view all the answers

Match the following components of ATP synthase with their functions:

F1 = a) ATP production β subunits = b) Proton flow and rotation ATP synthase = c) Catalytic mechanism Signup and view all the answers

The proton gradient releases ATP from the enzyme to the solution.

True Signup and view all the answers

What is the major energy barrier in the reaction catalyzed by ATP synthase?

The release of ATP from the enzyme to the solution. Signup and view all the answers

What is the role of the proton gradient in ATP production?

To release ATP from the enzyme Signup and view all the answers

What is the result of proton pumping during the electron transport chain?

The matrix becomes more basic and negatively charged and the intermembrane space becomes more acidic and positively charged Signup and view all the answers

The energy stored in the proton-motive force is used to directly react ADP + Pi to ATP.

False Signup and view all the answers

What is the proton-motive force (PMF)?

A 'battery' storing energy for eventual ATP synthesis, composed of chemical and electrical potential energy. Signup and view all the answers

The energy of electron transfer is efficiently conserved in a _______________ gradient.

proton motive force Signup and view all the answers

What is the role of ATP synthase in ATP synthesis?

To react ADP + Pi to ATP Signup and view all the answers

The electron transport chain and ATP synthesis are decoupled processes.

False Signup and view all the answers

Match the components of the proton-motive force (PMF) with their descriptions:

Chemical potential energy = Due to the difference in concentration of a chemical species (H+) in the two regions separated by the membrane Electrical potential energy = Resulting from the separation of charge when a proton moves across the membrane without a counterion Signup and view all the answers

What is the net result of proton pumping during the electron transport chain in terms of proton movement?

10 H+ are pumped out of the mitochondrial matrix, and 2H+ are removed from the matrix into water. Signup and view all the answers

Study Notes

ATP Synthesis

ATP synthesis occurs in the β subunits of ATP synthase (F1 head group)
The reaction ADP + Pi => ATP + H2O is reversible with a free energy change of 0
ATP synthase stabilizes ATP relative to ADP + Pi by binding ATP more tightly (Kd 10^(-12) : 10^(-5))
The binding energy drives the equilibrium toward ATP formation
The proton gradient releases ATP from the enzyme

Proton Gradient and Electron Flow

The energy of electron transfer is efficiently conserved in a proton gradient (proton motive force, PMF)
From 1 NADH oxidized, 10 H+ are pumped plus removing 2H+ from the matrix into water
As electrons flow between carriers, H+ are pumped out of the mitochondrial matrix
The matrix becomes more basic and negatively charged, while the intermembrane space becomes more acidic and positively charged

Proton Motive Force (PMF)

The proton motive force is a "battery" storing energy for eventual ATP synthesis
The energy stored in the gradient has two components: chemical potential energy and electrical potential energy