C2 Cycle

🌿 C₂ Cycle / Photorespiration – Explained Simply

The C₂ cycle, also called photorespiration, is a process that occurs in green plants when the enzyme RuBisCO binds with oxygen (O₂) instead of carbon dioxide (CO₂) during photosynthesis.

This usually happens:
✅ At high temperature
✅ When CO₂ levels are low
✅ O₂ levels are high
✅ In bright sunlight

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🔄 What Happens in the C₂ Cycle?

The reaction involves three cell organelles working together:

1. Chloroplast
RuBisCO uses O₂ and forms a toxic compound called 2-phosphoglycolate.

2. Peroxisome
This converts the compound into glycine.

3. Mitochondria
Two glycine molecules combine to release CO₂ and form serine.

The serine is sent back to the peroxisome and then the chloroplast, finally re-entering the Calvin cycle.

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⚠️ Why is Photorespiration Wasteful?

❌ CO₂ is released instead of fixed
❌ No sugar or ATP is produced
❌ Energy is consumed

So, the C₂ cycle reduces photosynthesis efficiency.




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