1 / 32

Photosynthesis

Photosynthesis. Light energy. CO 2. H 2 O. C 6 H 12 O 6. O 2. 6. +. 6. +. 6. Carbon dioxide. Water. Glucose. Oxygen gas. PHOTOSYNTHESIS. 0. Photosynthesis. 0. Human demand for energy Fossil fuel supplies? Energy plantations Biomass energy. Carbon and Energy.

ivana-cummings
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

  2. Light energy CO2 H2O C6H12O6 O2 6 + 6 + 6 Carbon dioxide Water Glucose Oxygen gas PHOTOSYNTHESIS 0 Photosynthesis

  3. 0 • Human demand for energy • Fossil fuel supplies? • Energy plantations • Biomass energy

  4. Carbon and Energy • Photoautotrophs • C source? • Energy source? • Heterotrophs • C source? • Energy source?

  5. Figure 7.1A–D Photoautotrophs

  6. Mesophyll Cell Leaf Cross Section Leaf Mesophyll LM 2,600  Chloroplast Vein Stoma O2 CO2 Chloroplast Outer membrane TEM 9,750  Inner membrane Stroma Intermembrane space Stroma Grana Thylakoid Granum Thylakoid space Where does PS happen? • Green parts… • Chloroplasts (stroma and thylakoids) • Stomata

  7. Where does O2 come from? • By splitting water

  8. Reduction   6 O2 6 CO2 6 H2O C6H12O6 Oxidation Oxidation   6 H2O C6H12O6 6 CO2 6 O2 Reduction 0 Just like respiration? • Redox processes

  9. Photosynthesis Energy-storing Releases O2 Requires CO2 Aerobic Respiration Energy-releasing Requires O2 Releases CO2 Linked Processes

  10. H2O CO2 Chloroplast Light NADP+ ADP + P CALVIN CYCLE (in stroma) LIGHT REACTIONS (in thylakoids) ATP Electrons NADPH O Sugar 0 Overview 2 stages • The light reactions… • Energy capture • produce O2 • The Calvin cycle • Uses CO2 • Makes sugar • The Coenzymes • ATP • NADPH

  11. Increasing energy 1 nm 1 m 10–5 nm 10–3 nm 103 nm 106 nm 103 m Micro- waves Radio waves Gamma rays X-rays UV Infrared Light Reflected light Visible light 400 500 600 700 750 380 Wavelength (nm) Absorbed light Chloroplast 650 nm Transmitted light Visible Light

  12. Pigments Colors? • Wavelengths not absorbed • Chlorophylls a and b • Carotenoids

  13. Chlorophylls chlorophyll b chlorophyll a Wavelength absorption (%) Wavelength (nanometers)

  14. T.E. Englemann’s Experiment

  15. Photons • Packets of light energy • Shortest wavelength (blue-violet light) = highest energy

  16. Photosystem Reaction center Primary electron acceptor Light-harvesting complexes Photon Excited state To electron transport chain e– Heat Energy of electron e– Photon Thylakoid membrane Photon (fluorescence) Ground state Pigment molecules Chlorophyll molecule Transfer of energy Chlorophyll a molecule 0 Photons and Photosystems Strike chlorophyll in photosystem Excite an electron Figure 7.7B, C

  17. Photosystem Reaction center Primary electron acceptor Light-harvesting complexes Photon Excited state To electron transport chain e– Heat Energy of electron e– Photon Thylakoid membrane Photon (fluorescence) Ground state Pigment molecules Chlorophyll molecule Transfer of energy Chlorophyll a molecule • Photon energy transfer to reaction-center • Excites electron • Which is taken by the primary electron acceptor • Which leads to the ETC

  18. Photosystem: Harvester Pigments • When excited by light energy:

  19. Photon Photon Photosystem II Photosystem I + H+ NADPH NADP+ Stroma 1 6 e– 2 e– Thylakoid membrane 4 5 P700 1 P680 2 Thylakoid space 3 Electron transport chain Provides energy for synthesis of by chemiosmosis ATP H2O O2 + 2 H+ Electron Transfer Chain • Uses electrons from reaction center • Powers H+ pump to produce ATP • Produces NADPH

  20. e– ATP e– e– NADPH e– e– e– Mill makes ATP Photon e– Photon Figure 7.8B Photosystem II Photosystem I Electron Transfer Chain • Electrons move from photosystem II to I • Make ATP • Electrons from photosystem I • Reduce NADP+ to NADPH

  21. Chloroplast Stroma (low H+ concentration) H+ H+ Light Light ADP + P ATP H+ NADP+ H+ NADPH + H+ Thylakoid membrane H+ H+ H2O 1 H+ H+ H+ H+ + O2 H+ 2 H+ H+ 2 H+ Photosystem II Electron transport chain Photosystem I ATP synthase H+ Thylakoid space (high H+ concentration) ATP Production

  22. Light-Independent Reactions • They put the “synthesis” in photosynthesis • Calvin-Benson cycle • In stroma

  23. Overall reactants CO2 ATP NADPH Overall products Glucose ADP NADP+ Calvin-Benson Cycle Cyclic! RuBP is regenerated

  24. Figure 7.14_4

  25. C3 Plants • 1st stable molecule is 3C PGA • C3 plants: tomatoes, petunias, roses, daisies, avocados

  26. C3 Plants • Hot, dry days what happens? • Inside leaf? • O2 increases • CO2 drops • PS rate?

  27. C4 Pathway • CO2 miner • 4C oxaloacetate forms in bundle sheath cells • Grasses

  28. CAM Plants • Opens stomata at night • Forms 4C compound • Release CO2 • Succulents and cacti • Slow growing

  29. C4 and CAM

  30. Greenhouse Effect? • What is the role of PS in global warming?

  31. Some heat energy escapes into space Sunlight ATMOSPHERE Radiant heat trapped by CO2 and other gases Greenhouse Effect • Excess CO2 in the atmosphere

  32. Question of the Day Scientists at Stanford University conducted a study on California grasslands. They looked at the effects of increased levels of CO2 , soil nitrogen, and temperature (modeling our future) on plant growth. What did they find?

More Related