Bio- Photosynthesis

• The Calvin cycle, or light-independent reactions, occur in the stroma of chloroplasts and involve the conversion of carbon dioxide into glucose.
• The Calvin cycle is the second stage of photosynthesis, where carbon dioxide is fixed into organic compounds.
• CO2 reacts with RuBP to form two molecules of 3-PGA (triose phosphate).
• Range of visible light is 390nm to 730 nm
• Hill's reaction ( photolysis )- H2 comes from water as a result of photolysis and O2 is evolved
• Electrons for reduction of CO2 are obtained from water
• PS-1 (P700) is Fe-S type of reaction while PS-2 (P680) is pheophytin-quinone type of reaction
• PS-1 results in formation of NADPH
• Non cyclic photophosphorylation

  
• In cyclic photophosphorylation, photolysis of water and evolution of O2 doesn't take place as process involves only PS-1
• Carbon is broken down into carbohydrates in stroma in dark reactions
• Carboxylation: RuBP reacts with CO2 to form 6-Carbon intermediate which in presence of rubisco forms 3-PGA
• 3-PGA forms 1,3-diphosphoglyceric acid using ATP. It's reduced to 3-PGAL by NADPH
• Out of 12 molecules of 3-PGAL, 2 are used for synthesis of 1 glucose molecule and remaining 10 for regeneration of 6 molecules of RuBP
• For every 6 molecules of CO2 and RuBP used , 12 molecules of 3-PGAL are produced
• Calvin cycle regenerates ADP and NADP required for light reaction
• Photorespiration :

  
• C4 plants show kranz anatomy
• Dicarboxylic acid is the 1st stable product of photosynthesis
• Bundle sheath cells have large chloroplasts and are poor in grana
• C4 pathway

  
• CAM plants or found in deserts. They were first reported in family crassulaceae.
• In CAM plants , stomata are scotoactive
• CAM plants examples- kalanchoe , opuntia , aloe , etc
• CAM pathway