In the previous 5 blogposts we looked into different important events taking place during the process of photosynthesis in plants.
please find the links for those blogs below –
Today we will be looking into some important similarities and differences between various types of CO2 fixation mechanisms observed in plant photosynthesis.
|Cells involved in Pathway||Mesophyll cells||Mesophyll and bundle sheath cells||Mesophyll cells|
|Type of plants||All photosynthetic plants||Tropical plants||Plants growing in desert or arid regions|
|Definition||Major type of photosynthesis – first major product formed after CO2 fixation is a three carbon compound||First major product formed after CO2 fixation in mesophyll cells is a four carbon compound (Oxalo acetic acid ), this further breaks into a 3 carbon compound. 3 carbon compound formed enters C3 cycle in bundle sheath cells.||Fixation of CO2 occurs during night time and light absorption, glucose production involving C3 cycle occurs during day time. This process is called the CAM or crassulacean acid|
|Carboxylase enzyme||RuBisCO||PEP carboxylase in mesophyll cells and RuBisCO in bundle sheath cells||PEP carboxylase during night times and RuBisCO in day time|
|Intial CO2 acceptor||3-Posphoglycerate (3PGA)||Oxalo acetic acid (OAA)||Oxalo acetic acid (OAA)|
|Dark reactions requires||12 NADPH and 18 ATPs are required.||12 NADPH and 30 ATPs are required.||12 NADPH and 39 ATPs are required.|
|Leaf anatomy||Normal||Kranz||Xeromorphic ( leaves show wax coating)|
|Photorespiration||High||Minimum as CO2 fixation and C3 cycle takes place in two separate cells||Minimum as CO2 fixation and C3 cycle takes place at two different times ( night and day)|
|Examples||cereals Barley, Oats, Rice, and wheat etc..||Maize, Sugarcane, sorghum etc.,||orchids, cactus, pine apple, jade plant, etc.|