Photosynthesis/Cell Resp.

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Photosynthesis/Cell Resp.

  1. 1. Organelles and the Flow of Energy Photosynthesis & Cellular Respiration (Part 1 of 2) AP Biology Chapters 6.4, 7, & 8
  2. 2. Oxidation-Reduction Reaction (Redox) <ul><ul><li>Electrons pass from one molecule to another </li></ul></ul><ul><ul><ul><li>The molecule that loses an electron is oxidized </li></ul></ul></ul><ul><ul><ul><li>The molecule that gains an electron is reduced </li></ul></ul></ul><ul><ul><li>Both take place at same time </li></ul></ul><ul><ul><li>One molecule accepts the electron given up by the other. </li></ul></ul>
  3. 3. How Does it Flow? <ul><li>Photosynthesis: </li></ul><ul><ul><li>A process that captures solar energy to produce carbohydrates (Glucose), and it takes place in the chloroplasts. </li></ul></ul><ul><li>Cellular Respiration: </li></ul><ul><ul><li>Takes in and breaks down carbohydrates, and it takes place in the mitochondria. </li></ul></ul><ul><ul><ul><li>Equation is the opposite of photosynthesis. (Flip it!) </li></ul></ul></ul>
  4. 4. Electron Transport Chain (ETC) <ul><li>Membrane-bound carrier proteins found in mitochondria and chloroplasts </li></ul><ul><li>Physically arranged in an ordered series </li></ul><ul><ul><li>Starts with high-energy electrons and low-energy ADP </li></ul></ul><ul><ul><li>Pass electrons from one carrier to another </li></ul></ul><ul><ul><ul><li>Electron energy used to pump hydrogen ions (H + ) to one side of membrane </li></ul></ul></ul><ul><ul><ul><li>Establishes electrical gradient across membrane </li></ul></ul></ul><ul><ul><ul><li>Electrical gradient used to make ATP from ADP+P Chemiosmosis </li></ul></ul></ul><ul><ul><li>Ends with low-energy electrons and high-energy ATP </li></ul></ul>
  5. 5. Visual Aide for the ETC high-energy electrons e energy for synthesis of ATP electron transport chain low-energy electrons e
  6. 6. Chemiosmosis <ul><li>Defined as the production of ATP due to a hydrogen ion gradient across a membrane. </li></ul><ul><ul><li>Thykaloid Membrane = Chloroplast </li></ul></ul><ul><ul><li>Cristae Membrane = Mitochondria </li></ul></ul><ul><li>Occurs in chloroplasts and mitochondria as a result of energized electrons leading the pumping of hydrogen ions across a membrane through the channel of an ATP synthase complex. </li></ul>
  7. 7. Chemiosmosis Cont… <ul><li>ATP synthase complexes: </li></ul><ul><ul><li>Are defined as enzymes and their carrier proteins, and span the entire membrane. </li></ul></ul><ul><li>The flow of hydrogen ions through the channel provides the energy for the ATP synthase enzyme produce ATP from ADP + P. </li></ul>
  8. 8. Closer Look @ Chemiosmosis High H + concentration H + pump in electron transport chain H H H H H H H ATP ATP synthase complex ADP + P Low H + concentration energy from electron transfers
  9. 9. Photosynthesis <ul><li>Photosynthesis: </li></ul><ul><ul><li>A process that captures solar energy </li></ul></ul><ul><ul><li>Transforms solar energy into chemical energy </li></ul></ul><ul><ul><li>Energy ends up stored in a carbohydrate </li></ul></ul><ul><li>Photosynthetic organisms (algae, plants, and cyanobacteria) transform solar energy into carbohydrates </li></ul><ul><ul><li>Called autotrophs because they produce their own food. </li></ul></ul>
  10. 10. Photosynthesis <ul><li>Photosynthesis takes place in the green portions of plants </li></ul><ul><ul><li>Leaf of flowering plant contains mesophyll tissue </li></ul></ul><ul><ul><li>Cells containing chloroplasts </li></ul></ul><ul><ul><li>Specialized to carry on photosynthesis </li></ul></ul><ul><li>Raw materials for photosynthesis are carbon dioxide and water </li></ul><ul><ul><li>Roots absorb water that moves up vascular tissue </li></ul></ul><ul><ul><li>Carbon dioxide enters a leaf through small openings called stomata </li></ul></ul><ul><ul><li>Diffuses into chloroplasts in mesophyll cells </li></ul></ul><ul><ul><li>In stroma, CO 2 combined with H 2 O to form C 6 H 12 O 6 (sugar) </li></ul></ul><ul><ul><li>Energy supplied by light </li></ul></ul><ul><ul><ul><li>Chlorophyll and other pigments absorbs solar energy and energize electrons prior to reduction of CO2 to a carbohydrate </li></ul></ul></ul>
  11. 11. Leaves and Photosynthesis Grana Chloroplast Leaf cross section granum independent thylakoid in a granum mesophyll lower epidermis upper epidermis cuticle leaf vein outer membrane inner membrane thylakoid space thylakoid membrane overlapping thylakoid in a granum CO 2 O 2 stoma stroma stroma 37,000 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. © Dr. George Chapman/Visuals Unlimited
  12. 12. Animation Please note that due to differing operating systems, some animations will not appear until the presentation is viewed in Presentation Mode (Slide Show view). You may see blank slides in the “Normal” or “Slide Sorter” views. All animations will appear after viewing in Presentation Mode and playing each animation. Most animations will require the latest version of the Flash Player, which is available at http://get.adobe.com/flashplayer.
  13. 13. Photosynthetic Pigments <ul><li>Absorption Spectra </li></ul><ul><ul><li>Pigments found in chlorophyll absorb various portions of visible light </li></ul></ul><ul><ul><li>Graph showing relative absorption of the various colors of the rainbow </li></ul></ul><ul><ul><li>Chlorophyll is green because it absorbs much of the reds and blues of white light </li></ul></ul>
  14. 14. Photosynthetic Pigments Wavelengths (nm) Increasing wavelength a. The electromagnetic spectrum includes visible light. b. Absorption spectrum of photosynthetic pigments. Increasing energy Gamma rays X rays UV Infrared Micro- waves Radio waves visible light 500 600 750 Wavelengths (nm) 380 500 600 750 chlorophyll a chlorophyll b carotenoids Relative Absorption Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
  15. 15. Types of Reactions <ul><li>Light Reaction – takes place only in the presence of light </li></ul><ul><ul><li>They are the energy‑capturing reactions </li></ul></ul><ul><ul><li>Chlorophyll absorbs solar energy </li></ul></ul><ul><ul><li>This energizes electrons </li></ul></ul><ul><ul><li>Electrons move down electron transport chain </li></ul></ul><ul><ul><ul><li>Pumps H + into thylakoids </li></ul></ul></ul><ul><ul><ul><li>Used to make ATP out of ADP and NADPH out of NADP </li></ul></ul></ul><ul><li>Calvin Cycle Reaction takes place in stroma </li></ul><ul><ul><li>CO 2 is reduced to a carbohydrate </li></ul></ul><ul><ul><li>Use ATP and NADPH produced carbohydrate </li></ul></ul><ul><ul><li>They are synthetic reactions </li></ul></ul>
  16. 16. Photosynthesis Overview Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. thylakoid membrane ADP + P NADP + NADP ATP Calvin Cycle reactions Light reactions Solar energy H 2 O CO 2 CH 2 O O 2 stroma
  17. 17. Light Reactions - Photosynthesis <ul><li>Light reactions consist of two alternate electron pathways: </li></ul><ul><ul><li>Noncyclic electron pathway </li></ul></ul><ul><ul><li>Cyclic electron pathway </li></ul></ul><ul><li>Capture light energy with photosystems </li></ul><ul><ul><li>Pigment complex helps collect solar energy like an antenna </li></ul></ul><ul><ul><li>Occur in the thylakoid membranes </li></ul></ul><ul><li>Both pathways produce ATP </li></ul><ul><li>The noncyclic pathway also produces NADPH </li></ul>
  18. 18. Anatomy of Thykaloid Membrane <ul><li>PS I : </li></ul><ul><ul><li>Has a pigment complex and electron acceptors </li></ul></ul><ul><ul><li>Adjacent to enzyme that reduces NADP + to NADPH </li></ul></ul><ul><li>PS II : </li></ul><ul><ul><li>Consists of a pigment complex and electron-acceptors </li></ul></ul><ul><ul><li>Adjacent to an enzyme that oxidizes water </li></ul></ul><ul><ul><li>Oxygen is released as a gas </li></ul></ul><ul><li>Electron transport chain : </li></ul><ul><ul><li>Consists of cytochrome complexes </li></ul></ul><ul><ul><li>Carries electrons between PS II and PS I </li></ul></ul><ul><ul><li>Also pump H + from the stroma into thylakoid space </li></ul></ul><ul><li>ATP synthase complex : </li></ul><ul><ul><li>Has a channel for H + flow </li></ul></ul><ul><ul><li>Which drives ATP synthase to join ADP and P i </li></ul></ul>
  19. 19. Non-Cyclic Electron Pathway <ul><li>Takes place in thylakoid membrane </li></ul><ul><li>Uses two photosystems, PS-I and PS-II </li></ul><ul><li>PS II captures light energy </li></ul><ul><li>Causes an electron to be ejected from the reaction center (chlorophyll a ) </li></ul><ul><ul><li>Electron travels down electron transport chain to PS-I </li></ul></ul><ul><ul><li>Replaced with an electron from water </li></ul></ul><ul><ul><li>Which causes H + to concentrate in thylakoid chambers </li></ul></ul><ul><ul><li>Which causes ATP production </li></ul></ul><ul><li>PS-I captures light energy and ejects an electron </li></ul><ul><ul><li>Transferred permanently to a molecule of NADP + </li></ul></ul><ul><ul><li>Causes NADPH production </li></ul></ul>
  20. 20. Light Reactions: Noncyclic Electron Pathway NADPH 2H + H 2 O electron acceptor NADP + H + pigment complex pigment complex reaction center reaction center sun sun electron transport chain (ETC) Photosystem II Photosystem I NADPH thylakoid membrane solar energy Calvin cycle ATP Calvin cycle reactions energy level CO 2 CH 2 O Light reactions O 2 1 2 ADP+ P NADP + e - e - e e e e - e - electron acceptor CH 2 O H 2 O CO 2 O 2 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
  21. 21. Animation Please note that due to differing operating systems, some animations will not appear until the presentation is viewed in Presentation Mode (Slide Show view). You may see blank slides in the “Normal” or “Slide Sorter” views. All animations will appear after viewing in Presentation Mode and playing each animation. Most animations will require the latest version of the Flash Player, which is available at http://get.adobe.com/flashplayer.
  22. 22. Cyclic Pathways <ul><li>Uses only photosystem I (PS-I) </li></ul><ul><li>Begins when PS I complex absorbs solar energy </li></ul><ul><li>Electron ejected from reaction center </li></ul><ul><ul><li>Travels down electron transport chain </li></ul></ul><ul><ul><li>Causes H + to concentrate in thylakoid chambers </li></ul></ul><ul><ul><li>Which causes ATP production </li></ul></ul><ul><ul><li>Electron returns to PS-I (cyclic) </li></ul></ul><ul><li>Pathway only results in ATP production </li></ul>
  23. 23. Organization of a Thylakoid stroma P NADPH Calvin cycle reactions ATP thylakoid photosystem II Stroma NADP reductase NADP + H + H + Pq H + H + ATP synthase chemiosmosis electron transport chain photosystem I granum thylakoid membrane thylakoid space stroma ATP NADPH +ADP P O 2 2 + 2 1 Thylakoid space e - H 2 O CO 2 O 2 CH 2 O solar energy thylakoid membrane Light reactions ADP + NADP + NADP + NADP + NADP + e - e - H + H + H + H + H + e - H 2 O Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
  24. 24. Animation Please note that due to differing operating systems, some animations will not appear until the presentation is viewed in Presentation Mode (Slide Show view). You may see blank slides in the “Normal” or “Slide Sorter” views. All animations will appear after viewing in Presentation Mode and playing each animation. Most animations will require the latest version of the Flash Player, which is available at http://get.adobe.com/flashplayer.
  25. 25. ATP Production <ul><li>Thylakoid space acts as a reservoir for hydrogen ions (H + ) </li></ul><ul><li>Each time water is oxidized, two H + remain in the thylakoid space </li></ul><ul><li>Electrons yield energy </li></ul><ul><ul><li>Used to pump H + across thylakoid membrane </li></ul></ul><ul><ul><li>Move from stroma into the thylakoid space </li></ul></ul><ul><li>Flow of H + back across thylakoid membrane </li></ul><ul><ul><li>Energizes ATP synthase </li></ul></ul><ul><ul><li>Enzymatically produces ATP from ADP + P i </li></ul></ul><ul><li>This method of producing ATP is called chemiosmosis </li></ul>
  26. 26. C3 Photosynthesis/ Calvin Cycle <ul><li>A cyclical series of reactions </li></ul><ul><li>Utilizes atmospheric carbon dioxide to produce carbohydrates </li></ul><ul><li>Known as C3 photosynthesis </li></ul><ul><li>Involves three stages: </li></ul><ul><ul><ul><li>Carbon dioxide fixation </li></ul></ul></ul><ul><ul><ul><li>Carbon dioxide reduction </li></ul></ul></ul><ul><ul><ul><li>RuBP regeneration </li></ul></ul></ul>
  27. 27. C3/Calvin Cycle Cont… <ul><li>CO 2 is attached to 5-carbon RuBP molecule </li></ul><ul><ul><li>Result in a 6-carbon molecule </li></ul></ul><ul><ul><li>This splits into two 3-carbon molecules (3PG) </li></ul></ul><ul><ul><li>Reaction accelerated by RuBP Carboxylase (Rubisco) </li></ul></ul><ul><li>CO 2 now “fixed” because it is part of a carbohydrate </li></ul>
  28. 28. C3/Calvin Cycle (CO 2 Reduction) <ul><li>3PG reduced to BPG </li></ul><ul><li>BPG then reduced to G3P </li></ul><ul><li>Utilizes NADPH and some ATP produced in light reactions </li></ul>
  29. 29. The Calvin Cycle: Reduction of CO 2 NADPH NADP + ATP 3PG G3P BPG ADP + P As 3PG becomes G3P, ATP becomes ADP + and NADPH becomes NADP + P Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
  30. 30. C3/Calvin Cycle (Regeneration of RuBP) <ul><li>RuBP used in CO 2 fixation must be replaced </li></ul><ul><li>Every three turns of Calvin Cycle, </li></ul><ul><ul><li>Five G3P (a 3-carbon molecule) used </li></ul></ul><ul><ul><li>To remake three RuBP (a 5-carbon molecule) </li></ul></ul><ul><ul><li>5 X 3 = 3 X 5 </li></ul></ul>
  31. 31. The Calvin Cycle: Regeneration of RuBP As five molecules of G3P become three molecules of RuBP, three molecules of ATP become three molecules of ADP + . 3 ATP 5 G3P 3 RuBP 3 ADP + P P Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
  32. 32. Importance of Calvin Cycle <ul><li>G3P (glyceraldehyde-3-phosphate) can be converted to many other molecules </li></ul><ul><li>The hydrocarbon skeleton of G3P can form </li></ul><ul><ul><li>Fatty acids and glycerol to make plant oils </li></ul></ul><ul><ul><li>Glucose phosphate (simple sugar) </li></ul></ul><ul><ul><li>Fructose (which with glucose = sucrose) </li></ul></ul><ul><ul><li>Starch and cellulose </li></ul></ul><ul><ul><li>Amino acids </li></ul></ul>
  33. 33. Animation Please note that due to differing operating systems, some animations will not appear until the presentation is viewed in Presentation Mode (Slide Show view). You may see blank slides in the “Normal” or “Slide Sorter” views. All animations will appear after viewing in Presentation Mode and playing each animation. Most animations will require the latest version of the Flash Player, which is available at http://get.adobe.com/flashplayer.
  34. 34. Fate of G3P G3P starch fatty acid synthesis glucose phosphate + fructose phosphate cellulose sucrose amino acid synthesis10 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
  35. 35. C 4 Photosynthesis <ul><li>In hot, dry climates </li></ul><ul><ul><li>Stomata must close to avoid wilting </li></ul></ul><ul><ul><li>CO 2 decreases and O 2 increases </li></ul></ul><ul><ul><li>O 2 starts combining with RuBP instead of CO 2 </li></ul></ul><ul><ul><li>Photorespiration, a problem solve in C 4 plants </li></ul></ul><ul><li>In C 4 plants </li></ul><ul><ul><li>Fix CO 2 to PEP a C 3 molecule </li></ul></ul><ul><ul><li>The result is oxaloacetate, a C 4 molecule </li></ul></ul><ul><ul><li>In hot & dry climates </li></ul></ul><ul><ul><ul><li>Avoid photorespiration </li></ul></ul></ul><ul><ul><ul><li>Net productivity about 2-3 times C 3 plants </li></ul></ul></ul><ul><ul><li>In cool, moist, can’t compete with C 3 </li></ul></ul>
  36. 36. Chloroplast Distribution in C 4 vs. C 3 Plants C 3 Plant C 4 Plant bundle sheath cell bundle sheath cell mesophyll cells vein vein stoma stoma Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
  37. 37. CO 2 Fixation in C 4 vs. C 3 Plants Calvin cycle CO 2 G3P 3PG RuBP mesophyll cell CO 2 CO 2 C 4 G3 bundle sheath cell mesophyll cell a. CO 2 fixation in a C 3 plant, blue columbine, Aquilegia caerulea b. CO 2 fixation in a C 4 plant, corn, Zea mays Calvin cycle Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. b: © Nigel Cattlin/Photo Researchers, Inc.
  38. 38. CAM Photosynthesis <ul><li>Crassulacean-Acid Metabolism </li></ul><ul><ul><li>CAM plants partition carbon fixation by time </li></ul></ul><ul><ul><ul><li>During the night </li></ul></ul></ul><ul><ul><ul><ul><li>CAM plants fix CO 2 </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Forms C 4 molecules, </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Stored in large vacuoles </li></ul></ul></ul></ul><ul><ul><ul><li>During daylight </li></ul></ul></ul><ul><ul><ul><ul><li>NADPH and ATP are available </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Stomata closed for water conservation </li></ul></ul></ul></ul><ul><ul><ul><ul><li>C 4 molecules release CO 2 to Calvin cycle </li></ul></ul></ul></ul>
  39. 39. CO 2 Fixation in a CAM Plant Calvin cycle CO 2 CO 2 C 4 G3P CO 2 fixation in a CAM plant, pineapple, Ananas comosus night day Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. © S. Alden/PhotoLink/Getty Images.
  40. 40. Climatic Adaptation: Photosynthesis <ul><li>Each method of photosynthesis has </li></ul><ul><li>Advantages and disadvantages </li></ul><ul><li>Depends on the climate </li></ul><ul><li>C 4 plants most adapted to: </li></ul><ul><ul><li>High light intensities </li></ul></ul><ul><ul><ul><li>High temperatures </li></ul></ul></ul><ul><ul><ul><li>Limited rainfall </li></ul></ul></ul><ul><li>C 3 plants better adapted to </li></ul><ul><ul><ul><li>Cold (below 25°C) </li></ul></ul></ul><ul><ul><ul><li>High moisture </li></ul></ul></ul><ul><li>CAM plants better adapted to extreme aridity </li></ul><ul><ul><li>CAM occurs in 23 families of flowering plants </li></ul></ul><ul><ul><li>Also found among nonflowering plants </li></ul></ul>

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