Electron Transport Chain Energy Production

Year 11 Biology Cellular Respiration Unit ATP Synthesis and Energy Production

Review: Where We've Been

Glycolysis: Glucose → Pyruvate + 2 ATP Krebs Cycle: Pyruvate → CO₂ + NADH + FADH₂ Products so far: Limited ATP, lots of electron carriers Question: What happens to NADH and FADH₂?

The Electron Transport Chain

ETC Components and Functions

{"left":"Complex I: NADH dehydrogenase - receives electrons from NADH\nComplex II: Succinate dehydrogenase - receives electrons from FADH₂\nComplex III: Cytochrome bc1 complex - transfers electrons to cytochrome c\nComplex IV: Cytochrome c oxidase - transfers electrons to oxygen","right":"ATP Synthase: Uses proton gradient to make ATP\nCoenzyme Q: Mobile electron carrier between complexes\nCytochrome c: Protein that shuttles electrons\nOxygen: Final electron acceptor, forms water"}

Model the ETC Process

Work in pairs to trace electron flow Use the provided diagram worksheet Label each complex and its function Identify where protons are pumped Mark where ATP is produced Extension: Calculate total ATP yield

The Critical Role of Oxygen

Oxygen is the final electron acceptor Without oxygen, electrons have nowhere to go ETC stops → No proton gradient → No ATP Oxygen combines with electrons and protons to form water This is why we need to breathe!

Critical Thinking Challenge

What would happen if someone consumed a poison that blocked Complex I? Think about: • Electron flow • Proton pumping • ATP production • Cell survival

ETC Products and Energy Yield

Products: 32-34 ATP molecules per glucose Water (H₂O) formed from oxygen reduction NAD+ and FAD regenerated for reuse Heat energy (maintains body temperature) Total cellular respiration: ~38 ATP per glucose Compare to fermentation: only 2 ATP!