🌟 Elevator Pitch: The inner mitochondrial membrane is like a bustling subway station, with electrons hopping from one protein carrier to another in a sequence called the Electron Transport Chain (ETC). Imagine reduced NAD as the train loaded with energetic passengers (electrons), which transfers its passengers to the platforms (protein carriers) and powers the subway (mitochondrion)!

• Location: Inner mitochondrial membrane.
• Main characters: Groups of proteins that act as electron carriers.

🎬 Action: These proteins accept and then pass on electrons.

💡 Think of it like a relay race, where athletes (electrons) pass a baton to the next runner (carrier).

• Origin: Reduced NAD comes from glycolysis, the link reaction, and the Krebs cycle.
• Role: It's the first to hand over its pair of electrons to the start of the ETC.

🎬 Action: This handover changes the state of the carrier from oxidized to reduced, and simultaneously transforms the reduced NAD back to just NAD. It's like paying an entrance fee - you give up some coins (electrons) and your wallet feels lighter (returns to its original state).

💡 Real-world analogy: Imagine you're at an amusement park. Reduced NAD is like a ride token. When you give it to the ride operator (the electron carrier), the ride starts (energy is gained).