AP Bio electron transport chain and chemiosmosis

Complex I (NADH dehydrogenase) → function?

Oxidizes NADH to NAD+, transferring electrons to ubiquinone (CoQ).

True or False: Ubiquinone is a lipid-soluble electron carrier.

True. Ubiquinone (CoQ) moves within the lipid bilayer of the inner mitochondrial membrane.

What does Complex II (Succinate dehydrogenase) do?

Converts succinate to fumarate, reducing FAD to FADH2, transferring electrons to ubiquinone.

Fill in the blank: Cytochrome c is a __________ electron carrier.

soluble.

Complex III (Cytochrome bc1 complex) transfers electrons to which carrier?

Cytochrome c.

Compare Complexes I and II: main difference?

Complex I uses NADH; Complex II uses FADH2.

Complex IV (Cytochrome c oxidase) → final electron acceptor?

Oxygen (O2), forming water (H2O).

What role do iron-sulfur proteins play in the electron transport chain?

Act as electron carriers, facilitating electron transfer between complexes.

True or False: FADH2 enters the electron transport chain at Complex I.

False. FADH2 enters at Complex II.

What is the total ATP yield from NADH through the electron transport chain?

Approximately 2.5 ATP per NADH.

Complex I to IV: which complexes pump protons?

Complexes I, III, and IV pump protons into the intermembrane space.

What is the role of cytochromes in the electron transport chain?

They are heme-containing proteins that transfer electrons between complexes.

Fill in the blank: The electron transport chain is located in the __________ membrane.

inner mitochondrial.

How do reactive oxygen species (ROS) form in the electron transport chain?

Incomplete reduction of O2 leads to superoxide (O2-).

What is the significance of ubiquinol in the electron transport chain?

Ubiquinol (QH2) is the reduced form of ubiquinone, transporting electrons between complexes.

True or False: All electron carriers are membrane-bound proteins.

False. Some, like cytochrome c, are soluble.

What is chemiosmosis?

Process by which ATP is synthesized using the proton gradient created by the electron transport chain.

Describe ATP synthase function.

ATP synthase harnesses proton flow to convert ADP and inorganic phosphate into ATP.

Fill in the blank: ATP synthesis occurs in the ___.

Mitochondrial inner membrane.

True or false: Chemiosmosis occurs only in aerobic respiration.

False: Chemiosmosis can also occur in anaerobic organisms, though less efficiently.

Proton gradient direction during chemiosmosis?

Protons move from the intermembrane space into the mitochondrial matrix.

Compare oxidative phosphorylation to substrate-level phosphorylation.

Oxidative phosphorylation uses a proton gradient; substrate-level phosphorylation directly transfers phosphate to ADP.

What drives ATP production in chemiosmosis?

The flow of protons (H+) through ATP synthase down their concentration gradient.

True or false: ATP synthase can function without a proton gradient.

False: A proton gradient is essential for ATP synthase to produce ATP.

What is the role of the intermembrane space?

Holds protons pumped out during the electron transport chain, creating a gradient.

Calculate ATP yield from 1 glucose molecule.

Approximately 30-32 ATP molecules produced via aerobic respiration, including chemiosmosis.

What is required for ATP synthase to operate?

A proton motive force created by the electron transport chain.

Cause → Effect: Proton gradient established. What is the effect?

Drives ATP synthesis via ATP synthase.

What is the proton motive force?

The energy generated by the proton gradient that drives ATP synthesis.

Describe the importance of uncouplers.

Uncouplers dissipate the proton gradient, inhibiting ATP synthesis while electron transport continues.

What happens during ATP synthesis at ATP synthase?

ADP and inorganic phosphate combine to form ATP as protons flow through the enzyme.

List the substrates for ATP production in chemiosmosis.

ADP, inorganic phosphate, and protons (H+).

Energetic yield of aerobic respiration?

Approximately 30-32 ATP per glucose molecule.

What inhibits complex I of the ETC?

Rotenone; blocks electron transfer to coenzyme Q.

True or False: Chemiosmosis occurs without ATP synthase.

False; ATP synthase is essential for ATP production.

Fill in the blank: The proton gradient drives __________.

ATP synthesis.

Difference between NADH and FADH2 in ETC?

NADH donates electrons to complex I; FADH2 donates to complex II.

What regulates the rate of the electron transport chain?

NADH and FADH2 availability, ADP levels.

Cause → Effect: Low oxygen levels?

Decreased electron transport activity and ATP production.

Inhibitors of ATP synthase?

Oligomycin; prevents proton flow through ATP synthase.

Energetic yield comparison: Anaerobic vs Aerobic?

Anaerobic: 2 ATP; Aerobic: 30-32 ATP.

True or False: Cyanide affects complex IV.

True; it inhibits electron transfer to oxygen.

Formula for calculating ATP yield from NADH?

Each NADH yields approximately 2.5 ATP: $\displaystyle NADH ightarrow 2.5 ATP$.

What happens to proton motive force under uncouplers?

It dissipates, reducing ATP synthesis.