Mechanism of CO2 Fixation in C4 Plants

Mechanism of CO2 Fixation in C4 Plants - 4 plants are two...

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Mechanism of CO 2 Fixation in C 4 Plants CO 2 fixation occurs when CO 2 is bonded to a 3-carbon compound to produce a 4-carbon compound. This enzyme functions well even at extremely low CO 2 concentrations because it is unaffected by oxygen. This CO 2 fixation occurs within the mesophyll cells that surround the bundle sheath cells. The 4-carbon compound then moves into the bundle sheath and releases the CO 2 , thus raising the level of CO 2 and preventing photorespiration. The enzyme that fixes CO 2 in the mesophyll cells is PEP carboxylase (pepco). This process is called C 4 photosynthesis because the product of carbon fixation is a 4 carbon compound. The diagram below summarizes the path of CO 2 in C 4 plants. Efficiency of C 4 Photosynthesis This mechanism requires extra ATP but under hot, dry conditions C
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Unformatted text preview: 4 plants are two to three times more efficient than C 3 plants. In moderate weather, C 3 plants are at an advantage. CAM CAM (crassulacean-acid metabolism) photosynthesis is found in most desert plants, particularly the succulents (plants that store water in thick, fleshy leaves). CAM plants keep their stomata closed during the day to conserve water. At night, the stomata open to allow CO 2 to enter. CO 2 is incorporated into organic acids which are then stored within the mesophyll cells. During the day, CO 2 is released from the organic acids to supply the Calvin Cycle. CAM plants are 5 to 7 times more efficient than C 4 plants. The diagram below summarizes the path of CO 2 in CAM plants....
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This note was uploaded on 12/15/2011 for the course BIO BSC1010 taught by Professor Gwenhauner during the Fall '10 term at Broward College.

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Mechanism of CO2 Fixation in C4 Plants - 4 plants are two...

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