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Topic: C4 photosynthesis


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C4

In the News (Mon 28 May 12)

  
  C4 photosynthesis   (Site not responding. Last check: 2007-11-06)
photosynthesis is a common metabolic pathway found in land plant s living under arid conditions.
Photosynthesis Center The Photosynthesis Center at Arizona State University is a multidisciplinary group doing research in several areas of photosynthesis.
Photosynthesis Chapter of MIT Hypertext Biology Textbook Basic introduction to plant photosynthesis, includes brief explanations of the biochemistry involved.
www.serebella.com /encyclopedia/article-C4_photosynthesis.html   (318 words)

  
 C4   (Site not responding. Last check: 2007-11-06)
One of the primary biosynthetic processes involved in photosynthesis is the Calvin cycle, which can take one of 3 forms in most plants.
In C3 and C4 plants, carbon dioxide is taken up during the daylight hours; in CAM plants carbon dioxide is taken up only at night.
C4 photosynthesis is generally found in plants that come from high light regions.
www.duosearch.com /encyclopedia/c/c4/c4.shtml   (185 words)

  
 C3, C4 Photosynthesis, and CAM
Ehleringer, J. Photosynthesis and photorespiration: biochemistry, physiology, and ecological implications.
Ecophsyiological responses of C3 forbes and C4 grasses to drought and rain on a tallgrass prairie in northeastern Kansas.
Geographical and environmental distribution of C3 and C4 grasses in the Sinai, Negev, and Judean deserts.
www.cnr.uidaho.edu /ecophysiology/c3c4.htm   (1332 words)

  
 C4 carbon fixation - Wikipedia, the free encyclopedia
This increases the amount of photosynthesis and decreases the chances of photorespiration, a harmful process in which organic material and energy is lost from the plant due to high concentrations of oxygen.
C4 carbon fixation has evolved on several occasions in different groups of plants, so is an example of convergent evolution.
Plants which use C4 metabolism include sugarcane, maize, sorghum, Eleusine, Amaranthus, Euphorbia, and Cannabis.
en.wikipedia.org /wiki/C4_photosynthesis   (386 words)

  
 Brief review of c4 photosynthesis   (Site not responding. Last check: 2007-11-06)
The fundamentals of C4 photosynthesis are shown in a simplified form in the figure below.
As you will recall, the photosynthesis processes of C4 plants are divided between mesophyll and bundle sheath cells.
Two steps of C4 photosynthesis that occur in the mesophyll cells are the light-dependent reactions and a preliminary fixation of CO into a molecule called malate.
www.marietta.edu /~spilatrs/biol103/photolab/c4photo.html   (203 words)

  
 [No title]
C4 plants have succeeded in eliminating photorespiration by splitting the reactions of photosynthesis between two types of cells, mesophyll cells (MC) and bundle sheath cells (BSC) (Kranz anatomy).
In the C4 pathway, CO2 is initially fixed by PEPC (phosphoenolpyruvate carboxylase) in the MC to form oxaloacetate, a C4 compound.
Limitations in C3 photosynthesis are discussed from the standpoint of leaf developmental factors and photoacclimatory responses, and a "scaling up" approach is used to identify limitations at the cellular level, in photorespiration and in canopy performance.
www.irri.org /pubcat2000/CropScienceReview.doc   (1127 words)

  
 Botany online: Photosynthesis
Under strong light and limited amounts of carbon dioxide is the rate of photosynthesis dependent on the temperature.
A first experimental prove that the oxygen developed during the photosynthesis of green plants stems indeed from water was delivered by the British physiologist R. He detected that isolated chloroplasts give off oxygen in the presence of unnatural reducing agents like iron oxalate, ferricyanide or benzoquinone after exposure to light.
The statement that the oxygen produced during photosynthesis stems only from the breakdown of water was confirmed by S. KAMEN and J. HYDE in 1941 after the isotope technique had found its way to biochemistry.
www.biologie.uni-hamburg.de /b-online/e24/24.htm   (1116 words)

  
 Madison Heights Orchids - Photosynthesis   (Site not responding. Last check: 2007-11-06)
Photosynthesis is going on and CO2 diffuses in and is utilized to produce carbohydrates.
C4 plants may have stomata open in the day but they have two types of cells in their leaves.
There are two main paths to photosynthesis, one called the C3 and the other the C4 path, so called because one operates on three carbon compounds as precursors and the the other on molecules which have four.
www.eskimo.com /~robertc/madison/photo.htm   (1076 words)

  
 IRRI - International Rice Research Institute
The effectiveness of the CO2-concentrating mechanism in a C4 plant is discussed with respect to overcycling by the C4 pathway, the energetics of photorespiration, and CO2 diffusive resistance between Rubisco and phosphoenolpyruvate carboxylase.
Many features of C4 photosynthesis must be introduced into a C4 rice, and must operate with high efficiency and coordination, if RCF and yield are to be improved significantly.
C4 photosynthesis confers substantial benefits upon herbaceous plants in tropical environments, most notably in high-light habitats with frequent drought, heat, and salinity stress.
www.irri.org /science/abstracts/007.asp   (3830 words)

  
 Photosynthesis Excites Scientific Community   (Site not responding. Last check: 2007-11-06)
Photosynthesis, the mechanism plants use to generate food from the energy in sunlight and carbon dioxide in air, is more efficient in C4 plants, which have special features that allow them to capture extra carbon dioxide.
C4 photosynthesis had been thought to require two specialized cells sitting next to each other (a construction called Kranz anatomy)—one cell to collect the carbon dioxide and the other to condense and process the carbon dioxide into plant material.
Creating C4 crops is made doubly advantageous because C4 plants are especially successful in areas that are arid or hot and in soils with high salt content, all conditions increasingly met in agricultural regions.
www.sci.wsu.edu /cos/spectrum/table_of_contents/photosynthesis.html   (482 words)

  
 C-4 Pathway   (Site not responding. Last check: 2007-11-06)
Compartmentation of photosynthesis in cells and tissues of C4 plants -- Edwards...
Climate and the U.S. distribution of C4 grass subfamilies and decarboxylation va...
The Role of the C4 Pathway in Carbon Accumulation and Fixation in a Marine Diato...
www.scienceoxygen.com /biology/129.html   (240 words)

  
 Leaf-burning in Ia5125, a monogenic trait bearing on C3-C4 photosynthesis   (Site not responding. Last check: 2007-11-06)
There are a number of possible explanations, one of which is that the 5125 burn type plants have difficulty in the transfer of photosynthate from the mesophyll to the bundle sheath where the decarboxylation occurs.
The various races of corn and all of its known relatives that we have examined have only the "Krantz-type" of leaf anatomy that characterizes the C4 type of photosynthesis, as is summarized in Table I. Table I.
A C3 photosynthesis type of corn might be better able to cope with the low temperatures that occur in the early part of the growing season or at high altitudes and latitudes.
www.maizegdb.org /mnl/52/43galinat.html   (419 words)

  
 NADP-ME project - Hydrilla
C4 plants are more efficient in performing photosynthesis at the current atmospheric CO2 concentration, especially in warm environments.
Hydrilla is one of the subjects of study in the Photosynthesis Research Laboratory at the Department of Botany in the University of Florida.
The fact that all the C4 components are present in the same cell demonstrates that Kranz anatomy is not required for C4 photosynthesis.
www.clas.ufl.edu /users/gestavil/Laboratory_Webpage/NADPME_project.htm   (869 words)

  
 471/571 Week 3   (Site not responding. Last check: 2007-11-06)
Bunce, J. Nonstomatal inhibition of photosynthesis at low water potentials in intact leaves of a species from a variety of habitats.
Photosynthesis and freezing avoidance in Ohia (Metrosideros polymorpha) at treeline in Hawaii.
Stomatal limitation of photosynthesis and reduced growth of the halophyte, Plantago maritima, at high salinities.
biology.unm.edu /Pockman/bio471/week3.html   (814 words)

  
 222   (Site not responding. Last check: 2007-11-06)
Modeling of C3 and C4 light-use efficiencies under different combinations of atmospheric CO2 and temperature predicts that C4-dominated ecosystems should not have expanded until atmospheric CO2 concentrations reached the lower levels that are thought to have existed beginning near the end of the Miocene.
The C4 monocots generally have a higher quantum yield than C4 dicots and it is proposed that leaf venation patterns play a role in increasing the light-use efficiency of most C4 monocots.
The reduced quantum yield of most C4 dicots is consistent with their rarity, and it is suggested that C4 dicots may not have been selected until CO2 concentrations reached their lowest levels during glacial maxima in the Quaternary.
ecophys.biology.utah.edu /Labfolks/Ehleringer/Publications/222   (375 words)

  
 Metabolically Modified Rice Exhibits Superior Photosynthesis and and Yield
In engineering C4 photosynthesis, there are two important components to be considered: the biochemical pathway (enzymes) and the specialized leaf structure.
These results were totally unexpected since only one of the maize C4 pathway enzymes is being elevated in the transgenic rice plants and one would not expect this would be sufficient to concentrate CO2 as in a typical C4 plant.
In this regard, it is interesting to note that increased yields in new wheat cultivars, developed by CIMMYT in the past 30 years, are attributed to increased photosynthetic capacity, which is associated with an elevated stomatal conductance to CO2 diffusion.
www.biotech-info.net /metabolically.html   (1167 words)

  
 Biology 2402 Lecture Notes - Photosynthesis Part 2. The Dark Reactions
It is caused by a fundamental "inefficiency" of Rubisco.
A significant portion (25%) of the carbon in phosphoglycolate is lost as CO Plants must use energy to "recover" the remaining 75% of this carbon, which further limits the efficiency of photosynthesis.
Photosynthesis is slightly less efficient in C4 and CAM plants than C3 plants, since energy is required to "pump" CO This is manifest in a greater ATP requirement to fix 1 molecule of CO Return to:
www.ualr.edu /~botany/darkrxns.html   (1806 words)

  
 Re: Why hasn't C4 Photosynthesis taken over as the dominant process?
The problem with C3 photosynthesis is that it depends completely on open stomata (leaf pores) for its supply of carbon dioxide (CO2) for photosynthesis.
On the other hand, C4 plants have the special ability to function well whe n CO2 is low, which often occurs when stomata are closed in the daylight.
C4 photosynthesis is not necessarily better than C3, it simply makes life in hot dry environments less stressful for the plants that use it.
www.madsci.org /posts/archives/dec98/913127630.Bt.r.html   (274 words)

  
 Bio 120
C4 Photosynthesis - The initial CO fixation reaction in Photosynthesis involves the enzyme ribulose-1,5-bisphosphate carboxylase/oxygenase ( RuBisCO).
This CO enrichment allows C4 plants to sustain higher rates of photosynthesis than non C4 plants, especially at higher temperatures.
As in C4 plants the released CO is then fixed to RuBP and the resultant Calvin cycle occurs.
bioweb.wku.edu /courses/Biol120/images/C4.htm   (633 words)

  
 ARS | Publication request: The Growth Response of C4 Plants to Rising Atmospheric Co2 Concentrations: a Reassessment
Due to the importance of C4 grasslands in global carbon sequestration, recognition and understanding of the direct impact of rising atmospheric CO2 concentration remains a crucial area of interest.
We argue that bundle sheath leakiness, direct CO2 fixation in the bundle sheath or the immaturity of C4 photosynthesis in young C4 leaves are unlikely explanations for the CO2 responsiveness of C4 photosynthesis.
The interaction between elevated CO2, temperature, and shoot water relations on the growth and photosynthesis of C4 plants are identified as key areas needing urgent research.
ars.usda.gov /research/publications/publications.htm?SEQ_NO_115=104428   (447 words)

  
 Photosynthesis and the Web: 2002   (Site not responding. Last check: 2007-11-06)
"Photosynthesis and Time" by Govindjee and Matej Lexa ( http://www.life.uiuc.edu/govindjee/ptime/): The time sequence of the light reactions of photosynthesis are taught through a "click-on" window (with the four protein complexes in it), and through a movie.
There is a nice "Photosynthesis Education" site at http://www.life.uiuc.edu/govindjee/Psed_index.htm); slides made in 1998 on various aspects of photosynthesis starting at http://www.life.uiuc.edu/SpringGov/lectures/lecture04/slides through lecture07/slides Research publications in the areas of primary photochemistry; role of bicarbonate in Photosystem II; chlorophyll a fluorescence, among other topics can be found arranged according to journals and to topics.
Photosynthesis by D.O. Hall and K.K. Rao has gone through several editions and is still one of the best textbooks for the study of photosynthesis ( http://www.cup.org/ObjectBuilder/ObjectBuilder.iwx?processName=productPage&product_id=0521430364&origin=redirect).
photoscience.la.asu.edu /photosyn/photoweb/default.html   (9783 words)

  
 c4cam   (Site not responding. Last check: 2007-11-06)
In C4 plants, however, the vascular tissue is surrounded by an additional ring of bundle sheath cells that are closely connected with the spongy mesophyll (Taiz, Figs 8.9 and 8.10).
This doesn't happen in C4 plants, so C4 plants are often more competitive in environments with higher temperature (because C3 plants lose a lot of C to photorespiration).
C4 plants represent only about 3% of the world's flora (C3 are 87%; CAM are 10%), suggesting that not may plants use the C4 path.
www.acad.carleton.edu /curricular/BIOL/classes/bio359/study%20guides/c4%20cam/8c4cam.html   (2504 words)

  
 Botany online: Photosynthesis - Literature
EMERSON, R., and W. ARNOLD: A separation of the reactions of photosynthesis by means of intermittent light.
GAFFRON, H.: A tentative picture of the relation between photosynthesis and oxidation reactions in green plants.
TREBST, A., M. AVRON, Eds.: Photosynthesis I. In: Encyolop, of Plant Physiol., Vol.
www.biologie.uni-hamburg.de /b-online/e24/24e.htm   (469 words)

  
 Molecular evolution of phosphoenolpyruvate carboxylase for C4 photosynthesis in maize: comparison of its cDNA sequence ...
Molecular evolution of phosphoenolpyruvate carboxylase for C4 photosynthesis in maize: comparison of its cDNA sequence with a newly isolated cDNA encoding an isozyme involved in the anaplerotic function -- Kawamura et al.
Molecular evolution of phosphoenolpyruvate carboxylase for C4 photosynthesis in maize: comparison of its cDNA sequence with a newly isolated cDNA encoding an isozyme involved in the anaplerotic function
Molecular events associated with the evolution of an enzyme for C4 photosynthesis were investigated.
jb.oxfordjournals.org /cgi/content/abstract/112/1/147   (408 words)

  
 Links SQL: Biological Science/Plants Animals and The Environment/Botany/Photosynthesis
Photosynthesis is the process by which plants, some bacteria, and some protistans use the energy from sunlight to produce sugar.
This contains a detailed account of photosynthesis, which includes sections on the physics of light and the photosystem, the light and dark reactions (click on Next Page), and alternate pathways for photosynthesis.
This MIT hypertextbook chapter covers C4 mechanisms as well as chemosynthesis, with both text and diagrams.
www.mhhe.com /links/1253/1249/1181/1097   (218 words)

  
 C4 and C3 photosynthesis in the same cell
The released CO is refixed by Rubisco and assimilated through the enzymes of the photosynthetic carbon reduction (PCR) cycle to form sucrose and starch.
photosynthesis is thought to provide an evolutionary advantage in environments where CO concentrations are low, and enables enhanced water-use efficiency.
photosynthesis was first reported by Elena Voznesenskaya and her colleagues in the semi-succulent halophyte Borszczowia aralocaspica of the family Chenopodiaceae.
www.sbs.utexas.edu /islam/_private/content/Review%20of%20the%20week/C4%20%20and%20C3%20photosynthesis%20in%20the%20same%20cell.htm   (686 words)

  
 New Phytologist Abstract   (Site not responding. Last check: 2007-11-06)
photosynthesis is a series of anatomical and biochemical modifications that concentrate CO around the carboxylating enzyme Rubisco, thereby increasing photosynthetic efficiency in conditions promoting high rates of photorespiration.
photosynthesis occurred in the dicots, with at least 30 lineages.
Low atmospheric CO is a significant contributing factor, because it is required for high rates of photorespiration.
www.blackwellpublishing.com /abstract.asp?ref=0028-646X&vid=161&iid=2&aid=6&s=&site=1   (372 words)

  
 Biology120.Lectures11   (Site not responding. Last check: 2007-11-06)
However, the rate of photosynthesis is affected by a number of environmental factors.
While it is possible that not all lineages of plants were 'lucky' enough to evolve the C4 pathway, it is important to remember that adaptations are often beneficial only under certain sets of environmental conditions.
In fact, C4 plants, while more efficient at high light levels and/or leaf temperatures, are actually less efficient at lower temperatures/light levels.
bioweb.wku.edu /Courses/Biol120/McElroy/120lects11.htm   (443 words)

  
 c4
This higher concentration of CO2 prevents photorespiration and allows the plant to close its stomata during the hot hours of the day.
The C4 pathway is more expensive energetically than normal photosynthesis, but not as expensive as photorespiration ( where on a bad day plants may lose 30% of fixed carbon.
For this reason C4 plants are thought to have evolved in places where photorespiration was a serious problem for plants.
www2.mcdaniel.edu /Biology/botf99/photodark/c4.htm   (258 words)

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