4.2 - etc + chemiosmosis

Where does the Electron Transport Chain occur?

Inner mitochondrial membrane

What molecules enter the Electron Transport Chain?

NADH and FADH₂

What is the final electron acceptor?

Oxygen (O₂)

What is produced when oxygen accepts electrons?

Water (H₂O)

What is the main purpose of the ETC?

Use electrons from NADH and FADH₂ to create a proton (H⁺) gradient → make ATP

Use electrons from NADH and FADH₂ to create a proton (H⁺) gradient → make ATP

4 (Complex I, II, III, IV)

What happens at Complex I?

NADH is oxidized → electrons given to chain + H⁺ pumped

What happens at Complex II?

FADH₂ is oxidized → electrons enter chain (NO H⁺ pumped)

Which complexes pump protons (H⁺)?

Complex I, III, and IV

Which complex does NOT pump protons?

Complex II

What carries electrons between complexes?

• Ubiquinone (UQ)

• Cytochrome C

Step 1: What happens to NADH?

NADH → NAD⁺ + electrons → Complex I

• H⁺ pumped into intermembrane space

Step 2: What happens to FADH₂?

FADH₂ → FAD + electrons → Complex II

Step 3: What does UQ do?

Carries electrons from Complex I & II → Complex III

Step 4: What happens at Complex III?

Electrons transferred + H⁺ pumped

Step 5: What does Cytochrome C do?

Carries electrons → Complex IV

Step 6: What happens at Complex IV?

Electrons + O₂ + H⁺ → H₂O

Why does NADH produce more ATP than FADH₂?

NADH enters at Complex I (3 pumps), FADH₂ enters at Complex II (2 pumps)

Which produces more ATP: NADH or FADH₂?

NADH

What is a proton gradient?

High H⁺ concentration in intermembrane space vs matrix

What creates the proton gradient?

ETC pumping H⁺ across membrane

What is chemiosmosis?

Movement of H⁺ down gradient through ATP synthase

What enzyme makes ATP?

ATP synthase

What happens when H⁺ flows through ATP synthase?

ADP + Pi → ATP

Where is ATP made in this stage?

Mitochondrial matrix

What is oxidative phosphorylation?

ATP made using energy from electron transport + oxygen as final acceptor

What happens if there is NO oxygen?

• ETC stops

• No proton gradient

• channels get backed up/clogged

• No ATP produced

What does oxidation mean?

Loss of electrons

What does reduction mean?

Gain of electrons

Is oxygen oxidized or reduced?

Reduced

What are the final products of ETC?

• ATP

• Water (H₂O)

• Regenerated NAD⁺ and FAD

What drives ATP production in chemiosmosis?

Proton-motive force (H⁺ gradient)

What is the role of oxygen in cellular respiration?

Keeps electron flow moving by accepting electrons