Proton Motive Force Old Exam Questions

If you isolate mitochondria and place them in buffer of low pH, they begin to synthesize ATP. Why?

Lowering external pH increases the proton gradient across the inner membrane, increasing the chemiosmotic force by driving the ATP synthase

What feature determines the ELECTROSTATIC component of the chemiosmotic potential?

Z (the proton charge)

What is the primary function of chemical uncouplers?

They collapse the H+ gradient across the inner membrane

Define the correct P:O ratio:

P:O = (ADP molecules phosphorylation) / (oxygen atoms reduced)

ADP will rise on the outside and the pH will drop on the inside

What are substrates for Complex II?

Succinate and FADH2

What are true statements about the function of the F1F0 ATP synthase?

1. Each proton binds an Asp residue in an F0 channel

2. Rotation of F0 drives conformational changes in the F1 structure

• High H+ in the intermembrane space

• High ADP in the intermembrane space

• High ATP in the matrix

• Electron transport coupled to proton export from the matrix

• Proton translocation across the inner membrane coupled with ATP synthesis

• An intact inner membrane

How many protons are trans located by complex I for each electron pair supplied by NADH?

4

Under aerobic conditions, a mechanism is needed to deliver cytoplasmic reducing equivalents to the mitochondrial electron transport system. What statement correctly describes this process?

• NADH is oxidized by cytosolic glycerol-3-P-Dehydrogenase

• Ubiquinone is converted to ubiquinol

• Dihydroxyacetone phosphate is reduced to glycerol 3-phosphate