1 / 22

Photosynthesis

Photosynthesis. Modified by Georgia Agricultural Education Curriculum Office July, 2002. Photosynthesis - Basics. 3CO 2 + 6H 2 O C 3 H 6 O 3 + 3O 2 + 3H 2 O. 3 carbon sugars produced What is the transport sugar in plants? O 2 is liberated from the H 2 O. Energy. Wavelength.

zudora
Download Presentation

Photosynthesis

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Photosynthesis Modified by Georgia Agricultural Education Curriculum Office July, 2002

  2. Photosynthesis - Basics 3CO2 + 6H2O C3H6O3 + 3O2 + 3H2O 3 carbon sugars produced What is the transport sugar in plants? O2 is liberated from the H2O

  3. Energy Wavelength Photosynthesis - Light Energy and wavelength energy as wavelength

  4. Photosynthesis - Visible Spectrum Color Wavelength Energy Violetshort high Blue Green Yellow Red Far-Redlong low

  5. Photosynthesis - PS Action Spectrum Color Wavelength Energy Violetshort high Blue Green Yellow Red Far-Redlong low Peak between 430 - 500 nm Peak at about 680 nm

  6. Photosynthesis - Role of Pigments Electrons kicked up to higher energy level Absorbed light has 3 fates: 1. Fluorescence 2. Transfer energy 3. Transfer electrons

  7. Photosynthesis - Pigments Chlorophyll a required pigment, “the hanger” Chlorophyll b accessory pigment, “the tin foil” Carotenoids anti-oxidants, protect the chlorophyll Figure 7-13 in text yellow pigments are carotenoids

  8. Photosynthesis - The Reactions Energy Transduction Rxns light dependent harvesting energy from the sun Carbon Fixation either light or dark requires energy from 1st rxns fixes CO2 into sugars Both occur in chloroplast

  9. Photosynthesis - Energy Transduction Rxns Light dependent 2 photosystems, linkage pumps protons “purpose”: to generate ATP & NADPH Figure 7-15 in text note similarities to figure 6-16

  10. Photosynthesis - Carbon Fixation Rxns Dependent on energy “purpose”: to fix carbon, storing energy in bonds Calvin Cycle C3 pathway 1st product contains 3 carbons occurs inmost plants

  11. Photosynthesis - Photorespiration Rubisco affinity binds with both O2 and CO2 when it binds with O2, carbon is bound into other products energy must be used to salvage the C rubisco contains nitrogen which is commonly the limiting nutrient

  12. Photosynthesis - C4 Pathway “Warm season” plants many native prairie grasses 1st product contains 4 carbons use BOTH C3 and C4 pathways C fixed by PEP carboxylase in mesophyll prefers CO2 over O2 handles photorespiration problems product is shipped to bundle sheath cells Kranz anatomy the key to the C4 pathway: spatial separation

  13. C4 and C3 Pathways - Differences in Anatomy C4 - Kranz Anatomy C3 H2O CO2 CO2 H2O H2O and CO2 pass through stomatal openings

  14. Photosynthesis - CAM Pathway Succulent plants (like cacti) Crassulacean acid metabolism (CAM) use BOTH C3 and C4 pathways C fixed by PEP carboxylase in DARK allows plants to close stomata product is used in same cells must have HUGE vacuoles to store C the key to the CAM pathway: temporal separation allows internal cycling during drought pineapple is CAM

  15. C4 and C3 Pathways - Differences in Anatomy C4 - Kranz Anatomy C3 H2O CO2 CO2 H2O H2O and CO2 pass through stomatal openings

  16. 50 40 30 20 10 0 Photosynthesis - C4 and C3 Pathways 14.0 Transpiration both types For a given growth rate, C3 species use almost twice as much water as C4 species. (i.e., they have lower water use efficiencies (WUE) 11.2 C4 C3 8.4 Net Photosynthesis (µmol m-2 s-1) Transpiration (mmol m-2 s-1) 5.6 2.8 0 0 160 320 480 640 Leaf Conductance (mmol m-2 s-1)

  17. C4 and C3 Pathways - Light Saturation C3 species become light saturated more quickly provides advantage in low light environments C4 C3 Carbon Gain Light

  18. C4 and C3 Pathways - Effect of Temperature 60 330 ppm 1000 ppm 50 C4 40 Net Photosynthesis (µmol m-2 s-1) 30 C3 20 C4 C3 10 0 0 20 30 40 50 0 20 30 40 50 Leaf Temperature (°C)

  19. C4 and C3 Pathways - Photorespiration 60 C3, Low [O2] Conflict between CO2 and O2 places C3 species at a disadvantage C4 species are able to concentrate CO2 providing an advantage under low CO2 conditions C3 Ambient [O2] 50 40 C4, Ambient [O2] 30 Net Photosynthesis (µmol m-2 s-1) 20 10 0 -10 0 100 200 300 400 500 600 Intercellular [CO2] (ppm)

  20. 1920 1980 Global Change - CO2, N and Diversity Global N Fixation CO2 Concentration “Natural” Anthropogenic 0 2000 Year Year Diversity Time

  21. C4 and C3 Pathways - Effect of CO2 concentration Competitive advantage between C3 and C4 switches along CO2 gradient Low CO2:C4 advantage due to concentrating of CO2 Ambient CO2:net growth about equal but water use is greater in C3 High CO2:C3 advantage due to C4’s low CO2 saturation point and reduction of CO2 / O2 conflict in C3 C3 60 50 C4 40 700 ppm CO2 30 Net Photosynthesis (µmol m-2 s-1) 350 ppm CO2 200 ppm CO2 20 10 0 -10 0 100 200 300 400 500 600 Intercellular CO2 (ppm)

  22. PS Pathways - Further Reading Polley, H.W. 1997. Implications of rising atmospheric carbon dioxide concentration for rangelands. Journal of Range Management. 50:561-577. Pearcy, R.W., and J Ehleringer. 1984. Comparative ecophysiology of C3 and C4 plants. Plant. Cell and Environment. 7:1-13. Data presented in this slide set were adopted from these 2 sources. They are both excellent resources.

More Related