Photosynthesis Overview <ul><li>CO 2  + H 2 O  C 6 H 12 O 6  + O 2 </li></ul><ul><li>photosynthesis  – creating using ligh...
Photosynthesis: Two Major Processes <ul><li>The Light Reactions </li></ul><ul><li>Carbon Fixation </li></ul><ul><li>harves...
Photosynthesis
Photosynthesis
Chloroplast Structure
The Light Reactions <ul><li>Photoexcitation </li></ul><ul><li>Electron transport </li></ul><ul><li>Photophosphorylation (c...
Photoexcitation <ul><li>e -  gain energy when atoms absorb energy. </li></ul><ul><li>e -  fall back to lowest energy level...
Light Absorbing Pigments <ul><li>chlorophyll  – groups of light absorbing molecules in green plants </li></ul>
Chlorophyll Absorption Spectrum -Visible light drives photosynthesis. -the shorter the wavelength, the greater the energy ...
Other Light Absorbing Pigments <ul><li>carotenoids  – other pigment molecules that can collect light energy </li></ul>
Photosystems <ul><li>chlorophyll and other light absorbing pigments in the thylakoid make up a  photosystem protein </li><...
Photosystem Structure <ul><li>reaction centre  – chlorophyll  a is located in the region of the photosystem called the rea...
Photosystems <ul><li>Two purposes: </li></ul><ul><ul><li>to collect as much light energy as possible </li></ul></ul><ul><u...
Electron Transport <ul><li>Electron transport occurs in the thylakoid membrane. </li></ul><ul><li>Two mechanisms of electr...
Thylakoid Membrane Proteins
Thylakoid Proteins: PSII  <ul><li>2e -  transferred from H 2 O to  photosystem II  ( PS II ) </li></ul><ul><li>also known ...
Thylakoid Proteins: Pq <ul><li>e -  transferred to  plastiquinone  (Pq) only when enough energy is collected by PSII </li>...
Thylakoid Proteins: Cytochrome Complex <ul><li>e -  transferred from PQ to  cytochrome complex </li></ul><ul><li>protons p...
Chloroplast Structure
Thylakoid Proteins: Pc <ul><li>e- transferred to  plastocyanin  (Pc) </li></ul><ul><li>PC is a movable component on thylak...
Thylakoid Proteins: PSI  <ul><li>e- transferred to  photosystem I  (PSI) </li></ul><ul><li>also known as P700 (maximum 700...
Thylakoid Proteins:  Fd <ul><li>e -  transferred to  ferrodoxin  (Fd) only when enough energy has been collected by PSI </...
Thylakoid Proteins: NADP +  Reductase <ul><li>e -  transferred to  NADP +  reductase </li></ul><ul><li>final electron acce...
NADP+ / NADPH
Thylakoid Proteins: ATP Synthase <ul><li>protons pumped into the lumen pass through ATP synthase </li></ul><ul><li>ATP pro...
Non-cyclic Electron Flow: Z-Scheme
Non-cyclic Electron Transfer Summary <ul><li>H 2 O is split to produce O 2  (released from cell) and H +  ions (released i...
Analogy
Light Reaction Animation <ul><li>http://www.youtube.com/watch?v=v590JJV96lc </li></ul><ul><li>http://www.youtube.com/watch...
Cyclic Electron Flow
Cyclic Electron Transfer Summary <ul><li>only involves photosystem I (P700) </li></ul><ul><li>ferrodoxin returns electrons...
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04a photosynthesis-2010 update stacy

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  • - compare and contrast mitochondria and chloroplast structure
  • Q: What happens to electrons when light strikes them? A: Excited, gain energy, higher potential energy level - think of glow in the dark objects (the light we see is electrons falling back to ground state)
  • What is the primary light absorbing molecule in green plants? Why does it make plants appear green?
  • - compare and contrast mitochondria and chloroplast structure
  • lumen – inside grana stacks stroma – inside chloroplast Z enzyme – splits water to ½ O 2 and 2 H + photosystem II – aka P680 PQ – plastoquinone cytochrome complex PC – plastocyanin photosystem I – aka p700 Fd – ferrodoxin NADPH reductase – makes NADPH
  • 04a photosynthesis-2010 update stacy

    1. 2. Photosynthesis Overview <ul><li>CO 2 + H 2 O C 6 H 12 O 6 + O 2 </li></ul><ul><li>photosynthesis – creating using light </li></ul><ul><li>Only chloroplast organelles and special bacteria have the proteins necessary to carry out this function. </li></ul>light
    2. 3. Photosynthesis: Two Major Processes <ul><li>The Light Reactions </li></ul><ul><li>Carbon Fixation </li></ul><ul><li>harvest light energy to create ATP </li></ul><ul><li>Process of producing C 6 H 12 O 6 from CO 2 and H 2 O </li></ul>
    3. 4. Photosynthesis
    4. 5. Photosynthesis
    5. 6. Chloroplast Structure
    6. 7. The Light Reactions <ul><li>Photoexcitation </li></ul><ul><li>Electron transport </li></ul><ul><li>Photophosphorylation (chemiosmosis) </li></ul><ul><li>Absorption of light photons </li></ul><ul><li>Similar to ETC in mitochondria </li></ul><ul><li>ATP synthesis due to electrochemical gradient </li></ul>
    7. 8. Photoexcitation <ul><li>e - gain energy when atoms absorb energy. </li></ul><ul><li>e - fall back to lowest energy level ( ground state ) if it isn’t transferred to another molecule </li></ul>
    8. 9. Light Absorbing Pigments <ul><li>chlorophyll – groups of light absorbing molecules in green plants </li></ul>
    9. 10. Chlorophyll Absorption Spectrum -Visible light drives photosynthesis. -the shorter the wavelength, the greater the energy of each photon of that light. Chlorophyll a – absorbs reds and blues for photosynthesis.
    10. 11. Other Light Absorbing Pigments <ul><li>carotenoids – other pigment molecules that can collect light energy </li></ul>
    11. 12. Photosystems <ul><li>chlorophyll and other light absorbing pigments in the thylakoid make up a photosystem protein </li></ul>
    12. 13. Photosystem Structure <ul><li>reaction centre – chlorophyll a is located in the region of the photosystem called the reaction center. </li></ul><ul><li>-once chlorophyll a is excited by light, it loses an electron to the electron acceptor. </li></ul><ul><li>The electron acceptor traps the high energy electron before it returns back to ground state. </li></ul>
    13. 14. Photosystems <ul><li>Two purposes: </li></ul><ul><ul><li>to collect as much light energy as possible </li></ul></ul><ul><ul><li>excite chlorophyll a and transfer its electrons to an electron acceptor and through a series of proteins (electron transport) </li></ul></ul>
    14. 15. Electron Transport <ul><li>Electron transport occurs in the thylakoid membrane. </li></ul><ul><li>Two mechanisms of electron transport: </li></ul><ul><li>Non-cyclic electron flow </li></ul><ul><li>Cyclic electron flow </li></ul>
    15. 16. Thylakoid Membrane Proteins
    16. 17. Thylakoid Proteins: PSII <ul><li>2e - transferred from H 2 O to photosystem II ( PS II ) </li></ul><ul><li>also known as P680 (maximum absorption at 680nm wavelength) </li></ul><ul><li>light energy is required to help create O 2 </li></ul><ul><li>protons are released into the lumen </li></ul>
    17. 18. Thylakoid Proteins: Pq <ul><li>e - transferred to plastiquinone (Pq) only when enough energy is collected by PSII </li></ul><ul><li>PQ is a mobile component within the thylakoid membrane </li></ul>
    18. 19. Thylakoid Proteins: Cytochrome Complex <ul><li>e - transferred from PQ to cytochrome complex </li></ul><ul><li>protons pumped from stroma to lumen across thylakoid membrane </li></ul>
    19. 20. Chloroplast Structure
    20. 21. Thylakoid Proteins: Pc <ul><li>e- transferred to plastocyanin (Pc) </li></ul><ul><li>PC is a movable component on thylakoid surface in lumen </li></ul>
    21. 22. Thylakoid Proteins: PSI <ul><li>e- transferred to photosystem I (PSI) </li></ul><ul><li>also known as P700 (maximum 700 nm wavelength absorption) </li></ul>
    22. 23. Thylakoid Proteins: Fd <ul><li>e - transferred to ferrodoxin (Fd) only when enough energy has been collected by PSI </li></ul><ul><li>movable component on thylakoid surface in stroma </li></ul>
    23. 24. Thylakoid Proteins: NADP + Reductase <ul><li>e - transferred to NADP + reductase </li></ul><ul><li>final electron acceptor is NADP + that is reduced to NADPH </li></ul>
    24. 25. NADP+ / NADPH
    25. 26. Thylakoid Proteins: ATP Synthase <ul><li>protons pumped into the lumen pass through ATP synthase </li></ul><ul><li>ATP produced in stroma </li></ul><ul><li>photophosphorylation – light-dependent formation of ATP by chemiosmosis </li></ul>
    26. 27. Non-cyclic Electron Flow: Z-Scheme
    27. 28. Non-cyclic Electron Transfer Summary <ul><li>H 2 O is split to produce O 2 (released from cell) and H + ions (released into lumen) </li></ul><ul><li>enzyme complexes pump protons from stroma to lumen </li></ul><ul><li>NADP + is final electron acceptor and produces NADPH </li></ul><ul><li>chemiosmosis to synthesize ATP </li></ul>
    28. 29. Analogy
    29. 30. Light Reaction Animation <ul><li>http://www.youtube.com/watch?v=v590JJV96lc </li></ul><ul><li>http://www.youtube.com/watch?v=hj_WKgnL6MI&feature=related </li></ul>
    30. 31. Cyclic Electron Flow
    31. 32. Cyclic Electron Transfer Summary <ul><li>only involves photosystem I (P700) </li></ul><ul><li>ferrodoxin returns electrons back to cytochrome complex </li></ul><ul><li>protons pumped into lumen to produce more ATP through chemiosmosis </li></ul><ul><li>no NADPH produced </li></ul>

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