Q: Which of the following equations correctly represents the ATP yield from the oxidation of 2 NADH in liver cells?

$$2 \text{ NADH} = 20 \text{ H}^+ / 4 \text{ H}^+ = 5 \text{ ATP}$$

Question 1

Which component of the ATP synthase complex is directly responsible for the rotation that drives conformational changes in the catalytic headpiece?

Accepted Answer

The γ subunit

Question 2

Bongkrekic acid inhibits ATP synthesis by targeting which mitochondrial protein, and what is the consequence of this inhibition?

Accepted Answer

ATP/ADP translocase; blocks export of ATP and import of ADP

Question 3

According to the chemiosmotic theory, how many protons must flow through ATP synthase to generate one molecule of ATP?

Accepted Answer

$$4 	ext{ H}^+$$

Question 4

Which shuttle system is used in liver cells to transfer electrons from cytosolic NADH to mitochondrial NAD+, and why is it preferred over the muscle shuttle?

Accepted Answer

Malate-aspartate shuttle; it is more efficient

Question 5

What is the effect of oligomycin on mitochondrial ATP synthesis and oxygen consumption?

Accepted Answer

Blocks ATP synthesis but not O2 consumption if DNP is present

Question 6

The binding change mechanism model of ATP synthase describes three β subunit conformations. What are they, and what is their sequence during γ subunit rotation?

Accepted Answer

Tight (T), Loose (L), Open (O); O → L → T

Question 7

Which of the following equations correctly represents the ATP yield from the oxidation of 2 NADH in liver cells?

Accepted Answer

$$2 	ext{ NADH} = 20 	ext{ H}^+ / 4 	ext{ H}^+ = 5 	ext{ ATP}$$

Question 8

Atractyloside inhibits the ATP/ADP translocase by binding to which conformational state, and what is the result?

Accepted Answer

C state; blocks ADP import

Question 9

Why does the glycerol-3-phosphate shuttle result in a lower net ATP yield from glucose oxidation in muscle cells compared to liver cells?

Accepted Answer

It uses FAD as the coenzyme, which yields less ATP per electron pair

Question 10

Which of the following statements about the regulation of oxidative phosphorylation is correct?

Accepted Answer

ADP, AMP, and Pi are allosteric activators of oxidative phosphorylation

Question 11

What is the role of the phosphate translocase in mitochondrial ATP synthesis?

Accepted Answer

It imports inorganic phosphate (Pi) into the matrix, either as a symporter with H+ or as an antiporter with OH-

Question 12

Inherited mitochondrial diseases are most often transmitted through which parent, and why?

Accepted Answer

Mother, because egg cells donate mitochondria

Question 13

Which of the following best describes the effect of 2,4-dinitrophenol (DNP) on oxidative phosphorylation?

Accepted Answer

It uncouples proton flow from ATP synthesis, dissipating the proton gradient

Question 14

In the ATP synthase complex, which subunit contains the catalytic site for ATP synthesis, and what cofactor is required?

Accepted Answer

β subunit; Mg2+

Question 15

Which of the following is a multi-step process required for ATP synthesis in mitochondria?

Accepted Answer

ADP and Pi are imported into the matrix, protons flow through ATP synthase, and ATP is exported via ATP/ADP translocase

Question 16

Which residue in the c ring of ATP synthase is alternately protonated and deprotonated to drive rotation?

Accepted Answer

Asp59

Question 17

If cyanide is added to mitochondria, what is the expected effect on O2 consumption and ATP synthesis?

Accepted Answer

O2 consumption and ATP synthesis are both blocked

Question 18

Which of the following best explains why muscle cells use the glycerol-3-phosphate shuttle instead of the malate-aspartate shuttle?

Accepted Answer

It allows for rapid conversion of cytosolic NADH to ATP

Question 19

Which of the following is NOT a function of the stator in the ATP synthase complex?

Accepted Answer

Rotating the c ring

ATP Synthase, Mitochondrial Transport, and Regulation of Oxidative Phosphorylation

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