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...
Putting it all together <ul><li>The electrons that are lost from the chlorophyll molecule (which go through the pathway) a...
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. Putting it all together <ul><li>The electrons that are lost from the chlorophyll molecule (which go through the pathway) are replaced by electrons from the water molecule when it breaks apart....thus creating the protons for the gradient and oxygen for us. </li></ul>
    31. 32. Cyclic Electron Flow
    32. 33. 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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