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WH Y AR E P LAN TS G RE EN?

WH Y AR E P LAN TS G RE EN?. It's not that easy bein ' green Having to spend each day the color of the leaves When I think it could be nicer being red or yellow or gold Or something much more colorful like that… Kermit the Frog. WHY ARE PLA NTS GRE EN? .

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WH Y AR E P LAN TS G RE EN?

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  1. WHY ARE PLANTS GREEN? It's not that easy bein' green Having to spend each day the color of the leaves When I think it could be nicer being red or yellow or gold Or something much more colorful like that… Kermit the Frog

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

  3. THE COLOR OF LIGHT SEEN IS THE COLOR NOT ABSORBED AND SINCE PLANTS ARE GREEN THAT MEANS THAT COLOR IS NOT ABSORBED. • Chloroplasts absorb light energy and convert it to chemical energy Reflected light Light Absorbed light Transmitted light Chloroplast

  4. AN OVERVIEW OF PHOTOSYNTHESIS • Photosynthesis is the process by which autotrophic organisms use light energy to make sugar and oxygen gas from carbon dioxide and water Carbondioxide Water Glucose Oxygengas PHOTOSYNTHESIS

  5. AN OVERVIEW OF PHOTOSYNTHESIS Light • The light reactions convert solar energy to chemical energy • Produce ATP & NADPH Chloroplast NADP ADP + P Calvin cycle • 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 reactions

  6. 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

  7. Chloroplast LEAF CROSS SECTION MESOPHYLL CELL • The location and structure of chloroplasts LEAF Mesophyll Intermembrane space CHLOROPLAST Outer membrane Granum Innermembrane Grana Stroma Thylakoidcompartment Stroma Thylakoid

  8. Chloroplast Pigments • Chloroplasts contain several pigments • Chlorophyll a • Chlorophyll b • Carotenoids Figure 7.7

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

  10. Different pigments absorb light differently

  11. Two types of photosystems: Photosystem 1 and photo system 2 cooperate in the light reactions Photon ATP mill Photon Water-splitting photosystem NADPH-producing photosystem

  12. Plants produce O2 gas by splitting H2O • The O2 liberated by photosynthesis is made from the oxygen in water (H+ and e-)

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

  14. In the light reactions, electron transport chains generate ATP, NADPH, & O2 • Two connected photosystems collect photons of light and transfer the energy to chlorophyll by electrons • The excited electrons are passed from the primary electron acceptor to electron transport chains • Their energy ends up in ATP and NADPH

  15. 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

  16. Light reactions • NADPH is converted in the calvin cycle back to NADP (H is used to make glucose) • NADPH and ATP is used to make glucose • ATP Uses the pumping of H out of the membrane to make ADP • The ADP, NADP and a proton (H+) are transferred back to chlorophyll to start over again.

  17. Chloroplast • A Photosynthesis Road Map Light Stroma NADP Stack of thylakoids ADP + P Light reactions Calvin cycle Sugar used for  Cellular respiration  Cellulose  Starch  Other organic compounds

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

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