Inside the powerhouses of our cells, the mitochondria, a cycle of reactions spins like a bicycle wheel. This wheel is known as the Krebs cycle, named for the biochemist who discovered it (and won a Nobel Prize, by the way).

• Acetyl groups make an entrance via a link reaction, taking center stage in this cellular drama.

• These groups transfer from the coenzyme A to oxaloacetate, crafting the organic acid citrate. 🍋

  (Imagine it like a fusion dance between a group with 4 carbon atoms (oxaloacetate) and a group with 2 carbon atoms (from the acetyl group) resulting in the 6-carbon dance star, citrate).

• Through a series of backstage, enzyme-led tweaks, citrate gets converted back to oxaloacetate. How? By dropping off 2 carbon atoms as carbon dioxide in two different decarboxylation reactions.

  🌬️ Fun Fact: In aerobic respiration, every carbon atom in foodie favorites like sugar or fats takes its leave via the Krebs cycle, or the link reaction, breathing out as carbon dioxide.

• Energy Alert! 🚨 In the Krebs cycle, four reactions turn up the energy. These reactions are oxidations.

  🔋 So, where does this energy go? It's stored by electrons, which then hop onto either the NAD or FAD bus. These buses not only transport electrons but also help pick up protons. Thus, they’re like hydrogen Uber drivers!

  👉🏻 Remember, when NAD or FAD pick up these electrons, they get "reduced." These charged-up carriers then pass their electron passengers to the electron transport chain in the inner mitochondrial membrane.