Photosynthesis in C3 vs. C4 plants
Ratesfor daily carbon assimilation by CAM plants are only about one-half those of C3plants and one-third those of C4.
Difference Between C4 and CAM Plants | Difference …
Moore, et al. say that only about 0.4% of the 260,000 known species of plants are C4 plants. But that small percentage includes the important food crops corn, sorghum, sugarcane and millet. Also inluded are crabgrass and bermuda. Many tropical grasses and sedges are C4 plants.
of CO2, rubisco is just as likely to bind to O2 PEP Carboxylase: enzyme that ONLY binds to CO2
will not bind to 02
will continue to bind CO2 to carbon compounds when CO2 concentrations are low CAM
both processes occur in the mesophyll cells
C4 pathway occurs at night; when it's cool CO2 binds temporarily and is stored as a 4-carbon acid called malate
Calvin in the day, malate is transferred to chloroplasts + converted to Co2 + pyruvate to enter Calvin
Cam Plants Vs C4 Plants Diagram Wiring Diagrams
The drawback to C4 photosynthesis is the extra energy in the form of that is used to pump the 4-carbon acids to the bundle sheath cell and the pumping of the 3-carbon compound back to the mesophyll cell for conversion to PEP. This loss to the system is why C3 plants will outperform C4 plants if there is a lot of water and sun. The C4 plants make some of that energy back in the fact that the rubisco is optimally used and the plant has to spend less energy synthesizing rubisco.
Moore, et al. point to Flaveria (Asteraceae), Panicum (Poaceae) and Alternanthera (Amarantheceae) as genera that contain species that are intermediates between C3 and C4 photosynthesis. These plants have intermediate leaf anatomies that contain bundle sheath cells that are less distinct and developed than the .
C4 vs CAM plants C4 photosyntehsis ..
C4 plants almost never saturate with light and under hot, dry conditions much outperform . They use a two-stage process were CO2 is fixed in thin-walled mesophyll cells to form a 4-carbon intermediate, typically malate (malic acid). The reaction involves phosphoenol pyruvate () which fixes CO2 in a reaction catalyzed by PEP-carboxylate. It forms oxaloacetic acid (OAA) which is quickly converted to malic acid. The 4-carbon acid is actively pumped across the cell membrane into a thick-walled bundle sheath cell where it is split to CO2 and a 3-carbon compound.
This design is an advantage to C4 plants because when the stomata are
closed and oxygen levels are high, the problem of photorespiration where the reaction of the rubisco enzyme with CO2 is competitively inhibited by oxygen, is diminished because the Calvin cycle is insulated from the light reactions. As a result we hypothesized that photosynthesis in C4 plants should have higher rates of photosynthesis than C3 plants when CO2 levels are low.
Relationship between C4 and CAM | Photosynthesis
What's the difference between C3, C4 and CAM plants?
C3 vs C4 vs CAM C3
What is the difference between C4 and CAM photosynthesis?
Difference between C3, C4 and CAM plants. A comparison of C3, C4 and CAM plants . C3 vs C4 vs CAM plants) C3 plants 1.
Pbio209_kb2variaciones c3 c4 y Cam | Plants | Photosynthesis
ADVERTISEMENTS: The upcoming discussion will update you about the Relationship between C4 and CAM
Another C3 and C4 photosynthesis lecture C 3 ..
The connection to hot and dry conditions comes from the fact that all the plants will close their stomata in hot and dry weather to conserve moisture, and the continuing fixation of carbon from the air drops the CO2 dramatically from the atmospheric concentration of nominally 380 ppm (2004 value). If the CO2 compensation point is lower on the above scale, the plant can operate in hotter and dryer conditions. The limits are placed by the fact that begins to fix oxygen rather than CO2, undoing the work of photosynthesis. C4 plants shield their rubisco from the oxygen, so can operate all the way down to essentially zero CO2 without the onset of photorespiration.
Chapter 10 - C4 and CAM - SlideShare
The CAM plants represent a metabolic strategy adapted to extremely hot and dry environments. They represent about 10% of the plant species and include cacti, orchids, maternity plant, wax plant, pineapple, Spanish moss, and some ferns. The only agriculturally significant CAM plants are the pineapple and an Agave species used to make tequila and as a source of fiber.
C4 Plants Adaptation to High Levels of CO2 and to …
The sketch below of the day-night cycle of the CAM plants is patterned after Moore, et al. The name Crassulacean Acid Metabolism came from the fact that this strategy was discovered in a member of the Crassulaceae which was observed to become very acidic at night and progressively more basic during the day.
C4 vs CAM Returning finally to the mechanisms of C4 and CAM: ..
We placed two different C3 plants, Juniper leaves and Gesneriacead, and a C4
plant, Corn, each into a chamber individually and attached the probe measuring
concentration of CO2. In each plant we left the lamps behind water bottles, to
maintain constant temperature, until the plant reached a point of equilibrium
where the rate of photosynthesis equals the rate of respiration. There was
significant difference between the results of each type of plant. The juniper
leaves had a point of equilibrium of 98ppm and Gesneriacead stopped absorbing
CO2 at 88ppm. Corn on the other hand had a point of equilibrium of 22ppm. This
proves that when CO2 levels are low, C4 plants have a higher rate of
photosynthesis and more success absorbing CO2 due to their specialized systems
reducing photorespiration. We determined that our results were consistent with
the hypothesis because the C4 plant has a better rate of photosynthesis.
Our results were consistent with our predictions and therefore we considered
our experiment reliable and we fail to reject our hypothesis but we could have
done more trials with other C3 and C4 plants to make the results more valid.
Results of Cohen et al. 2001 on the CABLE web site also concluded that C4
plants use CO2 more efficiently than C3 plants.
Contrasting C3, C4 and CAM Photosynthesis
The acidity was found to arise from the opening of their stomata at night to take in CO2 and fix it into malic acid for storage in the large vacuoles of their photosynthetic cells. It could drop the pH to 4 with a malic acid concentration up to 0.3M . Then in the heat of the day, the stomata close tightly to conserve water and the malic acid is decarboxylated to release the CO2 for fixing by the Calvin cycle. PEP is used for the initial short-term carbon fixation as in the , but the entire chain of reactions occurs in the same cell rather than handing off to a separate cell as with the C4 plants. In the CAM strategy, the processes are separated temporally, the initial CO2 fixation at night, and the malic acid to Calvin cycle part taking place during the day.
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