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Photorespiration:

Photorespiration:. * Rubisco catalyze its oxygenation ability omnipresent, even in anaerobic, autotrophic bacteria when exposed to oxygen * Loss of CO 2 from cells * Competition: decrease the efficiency of photosynthesis * Interconnection:

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Photorespiration:

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  1. Photorespiration: * Rubisco catalyze its oxygenation ability omnipresent, even in anaerobic, autotrophic bacteria when exposed to oxygen * Loss of CO2 from cells *Competition: decrease the efficiency of photosynthesis * Interconnection: determined by the kinetic properties of rubisco, the concentration of substrates, and temperature * C2 oxidative photosynthetic carbon cycle:act as a scavenger operation to recover fixed carbon lost during photorespiration

  2. Three organelles Carbon flow 22C13C+CO2 75% Nitrogen flow no changed Oxygen flow 3 O2/2 RuBP Malate-OAA shuttle supply NADH

  3. Web Topics 8.6[gas] µM = Pgas    106/ V0In vitro vs. In vivo Pgas: partial pressure; : absorption coefficient Solubility of CO2 and O2 as a function of temperature T  tilt toward the C2 oxidative photosynthetic cycle

  4. ROS

  5. Photorespiration depends on the photosynthetic electron transport system

  6. The biological function of photorespirationis under investigation ＊ a protective, to dissipate excess ATP and reducing power, especially under high light intensity and low [CO2]inter (e.g., water stress) ＊ mutants lack glycerate kinase, not viable in normal air ＊linked photorespiration to nitrate assimilation  a full understanding is still not at hand

  7. 0.03% CO2 / 21% O2 CO2-concentrating mechanisms: A. C4 photosynthetic carbon fixation (C4), in hot environment; B. Crassulacean acid metabolism (CAM), in desert environment; C. CO2 pumps at the plasma membrane. In aquatic plants, such as unicellular cyanobacteria and algae. In aquatic environment, [CO2] low rubisco specificity activity low CO2-HCO3-pumpsat the plasma membrane are induced, to accumulate inorganic carbon light energy provide ATP to uptake CO2 and HCO3- carbonic anhydrase: HCO3- + H+→ H2O +CO2 → Calvin cycle [CO2] ↑ suppress photorespiration

  8. Cyanobacterial CO2 concentrating mechanism — high homologous to the Rheus, a protein in erythrocytes

  9. spatial The C4 carbon cycle Kranz(wreath) cells:present two distinct chloroplast-containing cells, mesophyll and bundle sheath cells OAA

  10. Calvin cycle

  11. Poa sp sugarcane Flaveria australasica

  12. The C4 photosynthetic pathway:Hatch and Slack Gramineae (corn, millet, sorghum, sugarcane); Chenopodiaceae (Atriplex); Cyperaceae (sedges). external plasmodesmata specific translocators vascular NADP-ME: in chloroplast NAD-ME: in mitochondria PEP carboxykinase: in cytosol

  13. Web Topic 8.7 (?) Three variations of C4 metabolism The form of transportation The manner of decarboxylation (1) maize, crab grass, sugarcane, sorghum; (2) pigweed, millet; (3) guinea grass. Aspartate aminotransferase PEP carboxykinase Alanine aminotransferase

  14. Kranz anatomy: mesophyll and bundle-sheath cells carbon concentrating mechanism/ suppressed photorespiration Photosynthetic Carbon assimilation reduction plasmodesmata

  15. Borszczowia aralocaspica Bienertia cycloptera Chloroplasts containing rubisco are near mitochondria with NAD-ME

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