1. PHOTOSYNTHESIS http://www.youtube.com/ watch?v=tSHmwIZ9FNw

2. Objectives  Explain plant physiology concepts and energy conversion in plants.  a) Explain the basic process of photosynthesis and its importance to life on Earth.  b) Explain requirements necessary for photosynthesis to occur, and identify the products and byproducts of photosynthesis.  c)Explain cellular respiration and its importance to plant life.  d)Explain factors that affect cellular respiration, and identify the products and byproducts of cellular respiration.

3. Almost all plants are photosynthetic autotrophs, as are some bacteria and protists –Autotrophs generate their own organic matter through photosynthesis –Sunlight energy is transformed to energy stored in the form of chemical bonds (a) Mosses, ferns, and flowering plants (b) Kelp (c) Euglena (d) Cyanobacteria THE BASICS OF PHOTOSYNTHESIS

4. Light Energy Harvested by Plants & Other Photosynthetic Autotrophs 6 CO 2 + 6 H 2 O + light energy → C 6 H 12 O 6 + 6 O 2

5.  Photosynthesis is the process by which autotrophic organisms use light energy to make sugar and oxygen gas from carbon dioxide and water AN OVERVIEW OF PHOTOSYNTHESIS Carbon dioxide WaterGlucoseOxygen gas PHOTOSYNTHESIS

6. WHY ARE PLANTS GREEN? Plant Cells have Green Chloroplasts The thylakoid membrane of the chloroplast is impregnated with photosynthetic pigments (i.e., chlorophylls, carotenoids).

7.  Chloroplasts absorb light energy and convert it to chemical energy Light Reflected light Absorbed light Transmitted light Chloroplast THE COLOR OF LIGHT SEEN IS THE COLOR NOT ABSORBED

8. Photosynthesis occurs in chloroplasts  In most plants, photosynthesis occurs primarily in the leaves, in the chloroplasts  A chloroplast contains:  stroma, a fluid  grana, stacks of thylakoids  The thylakoids contain chlorophyll  Chlorophyll is the green pigment that captures light for photosynthesis

9.  The location and structure of chloroplasts LEAF CROSS SECTION MESOPHYLL CELL LEAF Chloroplast Mesophyll CHLOROPLAST Intermembrane space Outer membrane Inner membrane Thylakoid compartment Thylakoid Stroma Granum StromaGrana

10. Chloroplast Pigments  Chloroplasts contain several pigments –Chlorophyll a –Chlorophyll b –Carotenoids –Xanthophyll Figure 7.7

11. Chlorophyll a & b Chl a has a methyl group Chl b has a carbonyl group Porphyrin ring delocalized e - Phytol tail

12. Different pigments absorb light differently

13. The Calvin cycle makes sugar from carbon dioxide –ATP generated by the light reactions provides the energy for sugar synthesis –The NADPH produced by the light reactions provides the electrons for the reduction of carbon dioxide to glucose Light Chloroplast Light reactions Calvin cycle NADP  ADP + P  The light reactions convert solar energy to chemical energy  Produce ATP & NADPH AN OVERVIEW OF PHOTOSYNTHESIS

14. Steps of Photosynthesis  Light hits reaction centers of chlorophyll, found in chloroplasts Chlorophyll vibrates and causes water to break apart. Oxygen is released into air Hydrogen remains in chloroplast attached to NADPH “THE LIGHT REACTION”

15. Steps of Photosynthesis  The DARK Reactions= Calvin Cycle CO2 from atmosphere is joined to H from water molecules (NADPH) to form glucose Glucose can be converted into other molecules with yummy flavors!

16. Cyclic Photophosphorylation  Process for ATP generation associated with some Photosynthetic Bacteria

17. Photon Water-splitting photosystem NADPH-producing photosystem ATP mill  Two types of photosystems cooperate in the light reactions

18. Primary electron acceptor Electron transport chain Electron transport Photons PHOTOSYSTEM I PHOTOSYSTEM II Energy for synthesis of by chemiosmosis Noncyclic Photophosphorylation  Photosystem II regains electrons by splitting water, leaving O 2 gas as a by-product

19. Plants produce O 2 gas by splitting H 2 O  The O 2 liberated by photosynthesis is made from the oxygen in water (H + and e - )

20. In the light reactions, electron transport chains generate ATP, NADPH, & O 2  Two connected photosystems collect photons of light and transfer the energy to chlorophyll electrons  The excited electrons are passed from the primary electron acceptor to electron transport chains  Their energy ends up in ATP and NADPH

21. Chemiosmosis powers ATP synthesis in the light reactions  The electron transport chains are arranged with the photosystems in the thylakoid membranes and pump H + through that membrane  The flow of H + back through the membrane is harnessed by ATP synthase to make ATP  In the stroma, the H + ions combine with NADP + to form NADPH

22. 2 H  + 1 / 2 Water-splitting photosystem Reaction- center chlorophyll Light Primary electron acceptor Energy to make Electron transport chain Primary electron acceptor Primary electron acceptor NADPH-producing photosystem Light NADP  1 2 3 How the Light Reactions Generate ATP and NADPH

23. Video to help  http://www.youtube.com/watch?v=hj_W KgnL6MI http://www.youtube.com/watch?v=hj_W KgnL6MI

24. Summary—Light Dependent Reactions a. Overall input light energy, H 2 O. b. Overall output ATP, NADPH, O 2.

26.  Animation is of the Calvin Cycle Note what happens to the carbon dioxide and what the end product is. Animation is of the Calvin Cycle  Second animation of the Calvin Cycle is very clear and even does the molecular bookkeeping for you. Second animation of the Calvin Cycle

27. Light Independent Reactions aka Calvin Cycle Carbon from CO 2 is converted to glucose (ATP and NADPH drive the reduction of CO 2 to C 6 H 12 O 6.)

28. Light Independent Reactions aka Calvin Cycle CO2 is added to the 5-C sugar RuBP by the enzyme rubisco. This unstable 6-C compound splits to two molecules of PGA or 3-phosphoglyceric acid. PGA is converted to Glyceraldehyde 3- phosphate (G3P), two of which bond to form glucose. G3P is the 3-C sugar formed by three turns of the cycle.

29. Video to help  http://www.youtube.com/watch?v=o1I33 Dgcc_M http://www.youtube.com/watch?v=o1I33 Dgcc_M

30. Summary—Light Independent Reactions a. Overall input CO 2, ATP, NADPH. b. Overall output glucose.

31. Review: Photosynthesis uses light energy to make food molecules  A summary of the chemical processes of photosynthesis Light Chloroplast Photosystem II Electron transport chains Photosystem I CALVIN CYCLE Stroma Electrons LIGHT REACTIONSCALVIN CYCLE Cellular respiration Cellulose Starch Other organic compounds