Respiration Pathways & Respiratory Quotient

Fermentation vs. Aerobic Respiration 🍞💨

• Glucose breakdown: Fermentation only partially breaks down glucose → Aerobic respiration fully breaks it into CO₂ + H₂O
• ATP production: Fermentation makes only 2 ATP molecules per glucose → Aerobic respiration makes way more ATP! 🚀
• NADH recycling: NADH → NAD⁺ happens slowly in fermentation → Happens super fast in aerobic respiration 🔄

The Amphibolic Pathway 🔄✨

Respiration isn’t just for breaking things down! Glucose is the favorite starting point, but other molecules join the pathway too:

• Fats break into → Glycerol + Fatty acids
  • Fatty acids → Acetyl CoA (enters pathway)
  • Glycerol → PGAL (enters pathway)
• Proteins break into → Amino acids → Enter as pyruvate, Acetyl CoA, or join the Krebs’ cycle directly 🧬

Why “amphibolic”? This pathway works both ways!
🔹 Breaking down fats/proteins? They enter the respiratory pathway (catabolism)
🔹 Building fats/proteins? Cells grab intermediates like Acetyl CoA from the pathway (anabolism)
→ So it’s both a breakdown AND assembly line! 🤯

Respiratory Quotient (RQ) 📏

In aerobic respiration, we measure gas exchange:

RQ = \(\frac{\text{volume of CO}_2\text{ evolved}}{\text{volume of O}_2\text{ consumed}}\)

Fun fact: RQ changes based on what’s being respired!
For carbohydrates (like glucose):
→ CO₂ released = O₂ consumed → RQ = 1 ✅

Key NEET Concepts 💡

1. ATP difference: Fermentation (2 ATP) vs. Aerobic respiration (many ATP)
2. Amphibolic nature: Respiratory pathway = catabolic + anabolic hub
3. Substrate entry points: Fats → Acetyl CoA/PGAL; Proteins → amino acids enter at pyruvate/Krebs
4. RQ definition: RQ = \(\frac{\text{CO}_2\text{ evolved}}{\text{O}_2\text{ consumed}}\)
5. Carbohydrate RQ: Exactly 1 (equal CO₂ and O₂ exchange)

Keep exploring – you’re getting how cells power life! 🌱⚡