16 Questions
What is the energy yield from the electron transport chain for 1 NADH?
2.5 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
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
The proton gradient releases ATP from the enzyme to the solution.
True
What is the major energy barrier in the reaction catalyzed by ATP synthase?
The release of ATP from the enzyme to the solution.
What is the role of the proton gradient in ATP production?
To release ATP from the enzyme
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
The energy stored in the proton-motive force is used to directly react ADP + Pi to ATP.
False
What is the proton-motive force (PMF)?
A 'battery' storing energy for eventual ATP synthesis, composed of chemical and electrical potential energy.
The energy of electron transfer is efficiently conserved in a _______________ gradient.
proton motive force
What is the role of ATP synthase in ATP synthesis?
To react ADP + Pi to ATP
The electron transport chain and ATP synthesis are decoupled processes.
False
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
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.
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
ATP Yield from Complete Oxidation of Glucose
- 1 NADH produces 2.5 ATP
- 1 FADH2 produces 1.5 ATP
- Total ATP yield from complete oxidation of glucose: 36-38 ATP
Quiz about the catalytic mechanism of ATP synthase, including the ATP yield from NADH and FADH2, and the role of beta subunits in F1 head group.
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