Group 15Muhammad Rashidi Bin MdYusofMuhammad Amirul Bin JamaludinHaznul Bin Hamzah
Called C3 because the first product of photosynthesis is a 3-carbon molecule. Most plants are C3,usually on dicot plant . C3 photosynthesis is a multistep process in which the carbon from CO2 is fixed into stable organic products, it occurs in virtually all leaf mesophyll cells.
Rubisco, the enzyme involved in photosynthesis, is also the enzyme involved in the uptake of CO2. Photosynthesis takes place through out the leaf. Advantage of C3 : -More efficient than C4 plants under cool and moist conditions and under normal light because fewer enzymes and no specialized anatomy.
Called C4 because the first initial photosythesis product is a 4-carbon compound. C4 photosynthesis occurs in the more advanced plant taxa and is especially common among monocots, such as grasses and sedges C4 photosynthesis represents a biochemical and morphological modification of C3 photosynthesis to reduce Rubisco oxygenase activity and thereby increase photosynthetic rate in low CO2 environments.
Photosynthesis takes place in inner cells Surrounding the bundle sheath cells are mesophyll cells in which a much more active enzyme, Phosphoenolpyruvate (PEP) Carboxylase Uses PEP Carboxylase for the enzyme involved in the uptake of CO2. This enzyme allows CO2 to be taken into the plant very quickly, and then it delivers the CO2 directly to Rubisco for photosynthesis.
The additional cost of C4 photosynthesis is the adenosine triphosphate (ATP) requirement associated with the regeneration of PEP from pyruvate. C4 photosynthesis occurs primarily within monocotyledonous plants
Advantage of C4: Photosynthesis effecient than C3 plants under high light intensity and high temperatures because the CO2 concentration is high, not allowing it to grab oxygen and undergo photorespiration. Has better water use efficiency because PEP Carboxylase brings in CO2 faster and so does not need to keep stomata open as much (less water lost by transpiration) for the same amount of CO2 gain for photosynthesis.
In C3 plants the photosynthesis, carbon fixation and Calvin cycle all occur in a single chloroplast. In C4 plants the photosynthesis takes place in a chloroplast of a thin-walled mesophyll cell and a 4- carbon acid is handed off to a thick-walled bundle sheath cell where the Calvin cycle occurs in a chloroplast of that second cell. This protects the Calvin cycle from the effects of photorespiration.