1. Plant Cell nucleus chloroplast cytosol cell wall

2.  All photosynthetic reactions take place in the chloroplast  Light is captured in the chloroplasts with green pigments called cholorphylls Plant Cell nucleus chloroplast cytosol cell wall Chloroplast

3. The Chloroplast Outer membrane Inner membrane Stroma Thylakoid Granum

4. Thylakoid Thylakoid (contains chlorophyll) Stroma Lamella (connects grana) Thylakoid Space (Lumen)

5. PHOTOSYNTHESIS Stages of Photosythnesis  There are 2 main stages of photosynthesis: Light ReactionsDark Reactions makes NADPH ATP some glucose DON’T BE FOOLED!! Both light and dark reactions occur during the day. The “Dark” reactions don’t REQUIRE light while the “Light” reactions do!

6. PHOTOSYNTHESIS Stages of Photosynthesis  There are 2 main stages of photosynthesis: Light ReactionsDark Reactions makes NADPH ATP some glucose Light-Dependent ReactionsLight - Independent Reactions

7.  The full range of wavelengths of light emitted from the sun is known as the electromagnetic spectrum  Visible light is between 400-700nm  Light has properties of both waves and particles The Electromagnetic Spectrum

8. Light ~ as a particle?  Light travels in bundles of energy called photons  The energy from photons is used to initiate photosynthesis Photon

9. Capturing Light For the Light Reactions  Photosynthetic pigments absorb light  Each pigment can absorb light (photons) within a specific range of wavelengths  Wavelengths that are not absorbed are said to be transmitted or reflected This is the light we see ◦determines what colour we see

10. Chlorophyll a Chlorophyll b  The most common pigments in plants are Chlorophyll a and Chlorophyll b Capturing Light For the Light Reactions Absorbance: absorbed

11. Chlorophyll a Chlorophyll b  The most common pigments in plants are Chlorophyll a and Chlorophyll b Capturing Light For the Light Reactions GREEN What we see Reflection: reflected

12. Absorption Spectra for Chlorophyll

14. Other pigments  Though chlorophylls are the most common pigments, other pigments are present in plants to absorb at other wavelengths:  Carotenoids  Phycobilins  Xanthophylls

15. Other pigments

16. Harnessing Solar Energy!  How do plants store energy from photons into the chemical bonds of high energy molecules?  It starts in the thylakoids of the chloroplasts!

17. a The Light Reactions (light-independent reactions)  Groups of molecules responsible for the light reactions are called photosystems  Each photosystem has: 1.antenna pigments 200-400 chlorophyll b molecules, accessory pigments (ex. carotenoids) 2.reaction centre a specialized chlorophyll a molecule with associated proteins 3.primary electron acceptor PS II Electron Acceptor

18. How Photosystems Capture Light Energy  2 photosystems in plants:  Photosystem I (PS I) & Photosystem II (PS II)  Other names (used by text)  PS I absorbs best at 700nm; called P700  PS II absorbs best at 680nm; called P680 * Difference in absorbance is due to differences in proteins associated with chlorophyll a Thylakoid PS IPS IIP700P680

19. How Photosystems Capture Light Energy 1. Photons of light are absorbed by antenna pigments causing them to move from ground state to an excited state. 2.“Excitation” energy is passed along chlorophyll molecules until it reaches the reaction centre. 3. Chlorophyll a in the reaction centre absorbs the energy. 4.The high-energy state of chlorophyll a causes it to emit 2 electrons. 5.The primary electron acceptor takes the electrons from chlorophyll a.  this process is called photoexcitation Thylakoid PS IPS II aa a Electron Acceptor P

20. Homework  Read Section 3.3 up to “The Calvin Cycle”  Do section review 1-4 on pg.94  Explain the difference between the cyclic and non- cyclic pathway  Tomorrow we get into the nitty gritty details of how plants make ATP and Glucose! Excited?

21. Still to come  Time permitting I will show you a video that will show you plants as you’ve never seen them. It is made by my hero, Sir David Attenborough… sneak peak…

22. Non-Cyclical Electron Pathway  Photosystem II aquires a supply of electrons by using the sun’s energy to hydrolyze water.  This is called photolysis. PS II High Low Energy H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H2OH2O H+H+ H+H+ O2O2 H+H+ H+H+ H+H+ H+H+ P Stroma Thylakoid Lumen Thylakoid Membrane

23. Non-Cyclical Electron Pathway  The reaction center passes electrons through an electron transport system containing a cytochrome complex (cytochrome b6f)  This complex generates a proton gradient PS II High Low Energy H+H+ H+H+ H+H+ H+H+ Thylakoid Membrane Stroma Thylakoid Lumen E T C H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ PS I O2O2 ATP P  Electrons are re-energized at photosystem I  The high energy electrons are involved in a redox reaction to generate the high energy NADPH molecule  The proton gradient is used to generate ATP through ATP Synthase

24. Non-Cyclical Electron Pathway PS II High Low Energy H+H+ H+H+ H+H+ H+H+ Thylakoid Membrane Stroma Thylakoid Lumen E T C H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ PS I ATP NADP + NADPH

25. The End Result  These end products of the light reaction can now be used to synthesize glucose ATP NADPH

26. Cyclical Electron Pathway High Low Energy H+H+ H+H+ H+H+ H+H+ Membrane E T C H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ PS I ATP P  Simple organisms like bacteria are able to meet their energy demands by using PS I alone to generate ATP  In this way they generate cellular energy without synthesizing glucose.

27. Cyclical Electron Pathway High Low Energy H+H+ H+H+ H+H+ H+H+ Membrane E T C H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ PS I ATP P

32. The Dark Reaction

33. The Whole Process