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Forms of stored energy in cells

Forms of stored energy in cells

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Forms of stored energy in cells

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  1. Forms of stored energy in cells Electrochemical gradients Covalent bonds (ATP) Reducing power (NADH) During photosynthesis, respiration and glycolysis these forms of energy are converted from one to another How is H+ EC gradient generated?

  2. Photosynthesis and Respirationgenerate EC gradients used to make ATP Glycolysis and food Complementary processes Autotroph Hetrotroph Autotroph Fig. 3-10

  3. Lecture 7 Photosynthesis Overview Light reactions Excitation of electrons Electron transport chain Dark reactions Respiration - Mitochondrial electron transport Mitochondria structure Electron transport chain

  4. Chloroplast -plants and algae(in plasma membrane and cytoplasm of bacteria) ECB 14-30

  5. ‘Dark’ reactions = carbon fixation reactions Photosynthesis occurs in two stages(plants, algae, cyanobacteria) ‘Light’ reactions = photosynthetic e- transfer Occur in thylakoid membrane Carbon fixation - bonding CO2 into organic molecules H+ EC gradient ECB 14-32

  6. Proton gradient generated using energy from sunlight and e- transport chain Make ATP using F1F0 ATP synthase powered by a proton gradient H2O split to form O2 NADP+ reduced to NADPH by e- from e- transport chain Light reactions - overview

  7. Absorption spectra of pigments in plants Chlorophyll absorbs specific wavelengths of light; not all light is effective

  8. Conjugated double bonds stabilize excited electron Tail allows chlorophyll to insert in membrane Chlorophyll Structure Uses energy of an excited electron for: ECB 14-33

  9. Resonance energy transfer 2H2O O2 + 4 H+ Reaction center - site of charge separation Antenna complex chlorophyll ECB 14-34

  10. Charge separation at reaction center Takes 10-6 sec to complete!

  11. Donation of high energy e- to e- transport chain From last slide ECB 14-35 Ends at resting state

  12. P Chlorophyll in a special environment that allows for charge separation Q Primary electron acceptor P Q Ground state Absorbtion of a photon P* Q First excited state P+ Q- Primary charge separation e- e- P Q Ground state Charge Separation Summary (From H2O)

  13. Lecture 7 Photosynthesis Overview Light reactions Excitation of electrons Electron transport chain Dark reactions Respiration - Mitochondrial electron transport Mitochondria structure Electron transport chain

  14. High energy e- is donated to e- transport chain ECB 4-36

  15. ACIDIC and + charge Splitting of water leaves H+ in thylakoid space B6/f complex e- to plastocyanin moves H+ from stroma to thylakoid space e- to FNR reduces NADP in stroma, consumes H+ in stromal Net result is synthesis of NADPH and generation of H+ EC gradient Photosynthetic e- transport is vectorial 4 2 4

  16. High energy electron Low energy electron Electron Transport Chain Moves H+ Across membrane Moves a high-energy electron through a sequence of electron carriers (transmembrane proteins). A carries electrons Each step electron loses energy - directional sequence of carriers. B carries electron plus H+ Some carrier only only accept electrons, and other require a H+ to accompany the electron C only carries electrons Proton movement across membrane ECB 14-19

  17. e- energy drop H+ transport involves conformational changes in protein

  18. Z scheme of electron transport - energy High energy e- donated to e- transport chain Energy of electron Small E steps NADP+ is terminal e- acceptor Takes 2 photon to move 1 e- from H2O to NADP+ Antenna complex ECB 14-37

  19. NADPH (H+ + 2e-) Reduction occurs in stroma ECB 3-35

  20. EC gradient used to synthesize ATP Summary of light reactions in plants, algae and cyanobactia 14.6-light_harvesting.mov

  21. Lecture 7 Photosynthesis Overview Light reactions Excitation of electrons Electron transport chain Dark reactions Mitochondria structure Respiration - Mitochondrial electron transport Electron transport chain

  22. CO2 fixation Enzyme - ribulose bisphosphate carboxylase

  23. Carbon fixation - dark reactions Consume ATP and NADPH Bonds CO2 into organic molecules CO2 fixation phosphorylation Net 3 CO2 converted to a 3C organic molecule reduction

  24. Fate of gylceraldehyde 3 phosphate Enters glycolysis - next lecture Converted to sugars and starch in stroma and stored Starch can be converted back to sucrose and transported throughout plant to maintain energy needs (night)

  25. Chemiosmotic coupling is an ancient process Methanococcus- ancient archeabacterium thought to be primitive Generates H+ EC used to synthesize ATP - chemiosmotic coupling ECB 14-45

  26. Green sulfer bacteria use H2S as an e- donor and produce NADPH, (no ATP) Evolution of photosynthesis Like photosystem I

  27. Photosynthesis allowed respiration to evolve

  28. Lecture 7 Photosynthesis Overview Light reactions Excitation of electrons Electron transport chain Dark reactions Evolution of photosynthesis Respiration - Mitochondrial electron transport Mitochondria structure Electron transport chain

  29. Photosynthesis and Respiration Glycolysis and food Complementary processes Autotroph Hetrotroph Autotroph Fig. 3-10

  30. Respiration and Oxidative Phosphorylation bacteria mitochondria Photosynthesis chloroplasts ATP ADP + Pi Where in the cell is ATP made? 1. Bacterial plasma membrane 2. Mitochondrial inner membrane 3. Chloroplast thylakoid membrane

  31. Respiration in mitochondrion generates H+ EC gradient and ATP Mitochondrion and chloroplast have similar structures due to prokaryotic origins Extra membrane system-thylakoid membranes

  32. NADH Terminal e- acceptor is O2 (oxidative) NADH donates high energy e- *e- transport moves H+ outward *H+ flow inward generates ATP - oxidative phosphorylation Overview of mitochondrial e- transport ECB 14-13 Inside-out from photosynthesis in chloroplast

  33. NADH donates e- to electron transport chain

  34. H+ moved out across inner mito membrane at 3 steps 4 2 2 2 2 4 10 H+ pumped out per NADH oxidized

  35. Largest E steps Linked to H+ transport Electrons are passed down energy gradient High energy e- donor is NADH e- acceptor is oxygen

  36. FADH2 donates lower energy e- FADH2 4 2 2 2 e- 2 2 4 6 H+ pumped out per FADH2 oxidized

  37. FADH2 Structure Flavin Adenine Dinucleotide

  38. Cytochrome oxidase consumers almost all the oxygen we breath

  39. Energy conversions in respiration H+ EC gradient Reducing power in NADH used to generate H+ EC gradient which drives ATP synthesis H+ flow inward generates ATP - oxidative phosphorylation ATP must is then transported out of mitochondrion

  40. Evolution of oxidative phosphorylation ATP synthase generating H+ EC gradient to drive membrane transport Electron transport chain to generate H+ EC gradient Coupling of e- transport chain to ATP synthesis (synthase reversed) ECB 14-41

  41. Next topic -Where do NADH and FADH2 come from? Answer - Glycolysis and Krebs cycle (Recall that during photosynthesis, NADPH is made in light reactions and used in dark reactions)