Presentation on theme: "Photosynthesis is the process a plant uses to make food and grow."— Presentation transcript:
1 Photosynthesis is the process a plant uses to make food and grow. A definition:Photosynthesis is the process a plant uses to make food and grow.
2 Four things are needed for photosynthesis: SUNLIGHTGives the plant energyCHLOROPHYLLThe green stuff where the chemical reactions happenWATERTravels up from the rootsCARBON DIOXIDEEnters the leaf through small holes on the underneath
3 The word and chemical equations for photosynthesis: SunlightCarbon dioxide + water glucose + oxygen6CO H20 C6H12O O2ChlorophyllSunlightChlorophyll
4 THE SUN: MAIN SOURCE OF ENERGY FOR LIFE ON EARTH
5 THE BASICS OF PHOTOSYNTHESIS Almost all plants are photosynthetic autotrophs, as are some bacteria and protistsAutotrophs generate their own organic matter through photosynthesisSunlight energy is transformed to energy stored in the form of chemical bonds(c) Euglena(d) Cyanobacteria(b) Kelp(a) Mosses, ferns, andflowering plants
6 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
7 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
8 Light Energy Harvested by Plants & Other Photosynthetic Autotrophs 6 CO2 + 6 H2O + light energy → C6H12O6 + 6 O2
9 WHY ARE PLANTS GREEN? It has to do with sunlight! Sunlight is a form of electromagnetic energy, which travels in waves.
10 Electromagnetic Spectrum and Visible Light Gamma raysInfrared & MicrowavesX-raysUVRadio wavesVisible lightWavelength (nm):Distance between two waves
11 WHY ARE PLANTS GREEN?Different wavelengths of visible light are seen by the human eye as different colors.Gamma raysMicro- wavesRadiowavesX-raysUVInfraredVisible lightWavelength (nm)
12 The feathers of male cardinals are loaded with carotenoid pigments The feathers of male cardinals are loaded with carotenoid pigments. These pigments absorb some wavelengths of light and reflect others.Reflected lightSunlight minus absorbed wavelengths or colors equals the apparent color of an object.
13 THE COLOR OF LIGHT SEEN IS THE COLOR NOT ABSORBED Chloroplasts absorb light energy and convert it to chemical energyReflectedlightLightAbsorbedlightTransmittedlightChloroplast
14 Photosynthesis occurs in chloroplasts In most plants, photosynthesis occurs primarily in the leaves, in the chloroplastsA chloroplast contains:stroma, a fluid (site of Calvin Cycle)grana, stacks of thylakoids (site of Light reactions)The thylakoids contain chlorophyllChlorophyll is the green pigment that captures light for photosynthesis
15 The location and structure of chloroplasts LEAF CROSS SECTIONMESOPHYLL CELLLEAFMesophyllCHLOROPLASTIntermembrane spaceOutermembraneGranumInner membraneGranaStromaThylakoid compartmentStromaThylakoid
16 Chloroplast Pigments Chloroplasts contain several pigments Chlorophyll a: absorbs mainly violet and red light the bestChlorophyll b: absorbs blue and orange light the bestCarotenoids: absorbs blue and green bestFigure 7.7
18 Paper ChromatographyA laboratory test used to separate and analyze different pigments in a leaf.Example:https://www.pearsonsuccessnet.com/snpapp/iText/getTeacherHomepage.do?newServiceId=6000&newPageId=10100
19 Photosystems: Clusters of pigments in thylakoid membrane Photosystem ITraps light energy and transfers the light-excited electrons to an electron transport chain.Those excited electrons are replaced by splitting a molecule of water, which releases oxygen.The electron transport chain releases energy, which is used to make ATPPhotosystem IIProduces NADPH by transferring excited electrons and hydrogen ions to NADP+.
20 Light Reactions Photosystem I and Photosystem II SUMMARY: In the light reactions, electron transport chains generate ATP, NADPH, & O2Two connected photosystems collect photons of light and transfer the energy to chlorophyll electronsThe excited electrons are passed from the primary electron acceptor to electron transport chainsThe light reactions convert light energy to the chemical energy of ATP and NADPHWatch the following animation:
21 Two types of photosystems cooperate in the light reactions Inputs:WaterSunlight energyOutputs:OxygenATPNADPHPhotonATPmillPhotonWater-splittingphotosystemNADPH-producingphotosystem
22 Plants produce O2 gas by splitting H2O The O2 liberated by photosynthesis is made from the oxygen in water (H+ and e-)
23 How the Light Reactions Generate ATP and NADPH PrimaryelectronacceptorNADPEnergyto makePrimaryelectronacceptor32LightElectron transport chainLightPrimaryelectronacceptorReaction-centerchlorophyll1NADPH-producingphotosystemWater-splittingphotosystem2 H + 1/2
24 ELECTRON TRANSPORT CHAIN The production of ATP in photosynthesisThylakoid compartment (high H+)LightLightThylakoid membraneAntenna moleculesStroma (low H+)ELECTRON TRANSPORT CHAINPHOTOSYSTEM IIPHOTOSYSTEM IATP SYNTHASE
25 A Photosynthesis Road Map ChloroplastLightStromaNADPStack ofthylakoidsADP+ PLightreactionsCalvincycleSugar used for Cellular respiration Cellulose Starch Other organic compounds
26 Calvin CycleCalled a cycle because the starting material, RuBP, is regenerated.Uses carbon from carbon dioxide, the energy from ATP, and high energy electrons and hydrogen ions from NADPH to make a small sugar named G3P.The plant uses G3P to make glucose and other organic molecules.Overall input:CO2, ATP, NADPHOverall output:Glucose
29 Review: Photosynthesis uses light energy to make food molecules Light reactions use water and produce oxygen.The Calvin Cycle uses ATP and NADPH created in the the light reactions to convert carbon dioxide to glucose.ChloroplastLightPhotosystem II Electron transport chains Photosystem ICALVIN CYCLEStromaElectronsCellular respirationCelluloseStarchOther organic compoundsLIGHT REACTIONSCALVIN CYCLE
31 Animation is of the Calvin Cycle Note what happens to the carbon dioxide and what the end product is.Second animation of the Calvin Cycle is very clear and even does the molecular bookkeeping for you.