Presentation on theme: "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."— Presentation transcript:
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 Chloroplasts absorb light energy and convert it to chemical energy THE COLOR OF LIGHT SEEN IS THE COLOR NOT ABSORBED AND SINCE PLANTS ARE GREEN THAT MEANS THAT COLOR IS NOT ABSORBED.ReflectedlightLightChloroplasts absorb light energy and convert it to chemical energyAbsorbedlightTransmittedlightChloroplast
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 waterCarbon dioxideWaterGlucoseOxygen gasPHOTOSYNTHESIS
5 AN OVERVIEW OF PHOTOSYNTHESIS The light reactions convert solar energy to chemical energyProduce ATP & NADPHLightChloroplastNADPADP+ PThe Calvin cycle makes sugar from carbon dioxideATP generated by the light reactions provides the energy for sugar synthesisThe NADPH produced by the light reactions provides the electrons for the reduction of carbon dioxide to glucoseCalvincycleLightreactions
6 Photosynthesis occurs in chloroplasts In most plants, photosynthesis occurs primarily in the leaves, in the chloroplastsA chloroplast contains:stroma, a fluidgrana, stacks of thylakoidsThe thylakoids contain chlorophyllChlorophyll is the green pigment that captures light for photosynthesis
7 The location and structure of chloroplasts LEAF CROSS SECTIONMESOPHYLL CELLLEAFMesophyllCHLOROPLASTIntermembrane spaceOutermembraneGranumInner membraneGranaStromaThylakoid compartmentStromaThylakoid
11 Two types of photosystems: Photosystem 1 and photo system 2 cooperate in the light reactions PhotonATPmillPhotonWater-splittingphotosystemNADPH-producingphotosystem
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 PrimaryelectronacceptorNADPEnergyto makePrimaryelectronacceptor32LightElectron transport chainLightPrimaryelectronacceptorReaction-centerchlorophyll1NADPH-producingphotosystemWater-splittingphotosystem2 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 electronsThe excited electrons are passed from the primary electron acceptor to electron transport chainsTheir 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 membraneThe flow of H+ back through the membrane is harnessed by ATP synthase to make ATPIn the stroma, the H+ ions combine with NADP+ to form NADPH
16 Light reactionsNADPH is converted in the calvin cycle back to NADP (H is used to make glucose)NADPH and ATP is used to make glucoseATP Uses the pumping of H out of the membrane to make ADPThe ADP, NADP and a proton (H+) are transferred back to chlorophyll to start over again.
17 A Photosynthesis Road Map ChloroplastLightStromaNADPStack ofthylakoidsADP+ PLightreactionsCalvincycleSugar 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 photosynthesisChloroplastLightPhotosystem II Electron transport chains Photosystem ICALVIN CYCLEStromaElectronsCellular respirationCelluloseStarchOther organic compoundsLIGHT REACTIONSCALVIN CYCLE