Photosynthesis Page 7

• III. Hatch & Slack (C4) Photosynthesis
• A. Spatial separation of initial CO2 fixation and C3 cycle
• B. Mesophyll Cells
• 1. "normal" looking chloroplasts
• 2. CO2 + pyruvate + NADPH + H+ + 2 ATP -> malate + NADP+  2 ADP + 2 Pi
• 3. PEP carboxylate is insensitive to O2
• C. Malate transported to
• 
• D. Bundle Sheath Cells
• 1. chloroplasts lack grana
• 2. malate + NADP+ -> pyruvate + NADPH + H+ + CO2
• 3. Calvin Cycle proceeds in CO2 enriched environment
• E. Pyruvate transported to Mesophyll Cells
• F. More efficient under conditions of high light and high temperature
• 1. PEP carboxylase more efficient than RuBP under these conditions
• 2. CO2 concentrated at site of Calvin Cycle effectively eliminates photorespiration
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