Photorespiration uses 3.5 ATP per RuBP regenerated.
Here's a more detailed explanation:
Photorespiration is a process that occurs in plants when the enzyme RuBisCO binds to oxygen instead of carbon dioxide. This process is less efficient than photosynthesis, which fixes carbon dioxide to produce sugar. Photorespiration results in the release of carbon dioxide and uses ATP and NADPH. The reference provided specifically mentions:
The oxygenation pathway of photorespiration reportedly expends 3.5 ATP and 2 NADPH per RuBP regenerated but produces no additional organic carbon [19,20].
Therefore, for each molecule of RuBP that goes through photorespiration, 3.5 ATP molecules are consumed. The process does not produce any organic carbon unlike photosynthesis and is considered an energy-expensive process for plants.
Here's a summary in a table:
| Process | ATP Used | NADPH Used | Carbon Production |
|---|---|---|---|
| Photosynthesis (Carboxylation Pathway) | 3 | 2 | Yes |
| Photorespiration (Oxygenation Pathway) | 3.5 | 2 | No |
