Aerobic Respiration Notes 🌿💨

What is Aerobic Respiration?

It’s the complete breakdown of food using oxygen 🫧. This happens in mitochondria (the cell’s powerhouse) and releases:

• CO₂ (carbon dioxide)
• Water (H₂O)
• LOTS of energy (stored as ATP)

🔑 Key goal: Make ATP for cellular activities!

4 Steps of Aerobic Respiration

1. Pyruvate Transport 🚚

• After glycolysis (in cytoplasm), pyruvate moves into mitochondrial matrix

2. Pyruvate → Acetyl CoA 🔥

• Pyruvate loses a carbon (as CO₂) and becomes Acetyl CoA
• Reaction:
  \( \text{Pyruvic acid} + \text{CoA} + \text{NAD}^{+} \xrightarrow{\text{Mg}^{2+}} \text{Acetyl CoA} + \text{CO}_2 + \text{NADH} + \text{H}^{+} \)
• Products per glucose:
  • 2 Acetyl CoA
  • 2 NADH
  • 2 CO₂

3. Krebs Cycle (TCA Cycle) 🔄

• What happens: Acetyl CoA joins oxaloacetic acid (OAA) to make citric acid, then gets broken down step-by-step
• Where: Mitochondrial matrix
• Key products per Acetyl CoA:
  • 3 NADH 🟡
  • 1 FADH₂ 🔵
  • 1 ATP (or GTP) 💥
  • 2 CO₂ 💨
• Summary per glucose (2 turns):
  • 6 NADH, 2 FADH₂, 2 ATP, 4 CO₂

4. Electron Transport Chain (ETS) ⚡

• Goal: Use NADH & FADH₂ to make LOTS of ATP!
• Where: Inner mitochondrial membrane
• How:
  1. Electrons pass through protein complexes (I → IV)
  2. Energy pumps H⁺ ions into intermembrane space → creates proton gradient
  3. H⁺ flows back through ATP synthase (Complex V), making ATP:
     \( \text{ADP} + \text{Pi} \rightarrow \text{ATP} \)
  4. Oxygen (O₂) is FINAL electron acceptor → combines with H⁺ to form H₂O 💧
• ATP yield:
  • 1 NADH → 3 ATP
  • 1 FADH₂ → 2 ATP

Total ATP from 1 Glucose (Theoretical)

• Glycolysis: 2 ATP + 2 NADH
• Pyruvate → Acetyl CoA: 2 NADH
• Krebs Cycle: 6 NADH + 2 FADH₂ + 2 ATP
• ETS:
  • 10 NADH × 3 = 30 ATP
  • 2 FADH₂ × 2 = 4 ATP
• Total = 2 + 2 + 30 + 4 = 38 ATP

⚠️ Note: Real cells might make less (e.g., 30-32 ATP) because energy is used to move NADH into mitochondria and some ATP fuels other reactions.

NEET Super-Important Concepts! 🚨

1. Oxygen’s role: Final electron acceptor in ETS → makes H₂O. Without O₂, aerobic respiration STOPS! 🚫
2. Krebs Cycle outputs (per glucose): 6 NADH, 2 FADH₂, 2 ATP, 4 CO₂
3. ETS & Oxidative Phosphorylation:
   • ATP synthase uses H⁺ gradient to make ATP
   • 1 NADH = 3 ATP; 1 FADH₂ = 2 ATP
4. ATP Synthase Structure:
   • F₀: H⁺ channel in inner membrane
   • F₁: Makes ATP in matrix
5. Net ATP: 38 ATP per glucose (theoretical max)

Why is this awesome? 🤩

Aerobic respiration makes 18× more ATP than anaerobic respiration! 🙌 That’s why we need oxygen to run, think, and live!

✨ Fun fact: The Krebs cycle is named after Hans Krebs, who discovered it!