3 Learning OutcomesExplain how plants convert light into chemical energyDraw and describe the net reaction in photosynthesisExplain how photosynthesis has influenced the evolution of lifeExplain how light interacts with pigmentsDescribe the structures in a leaf that are involved in photosynthesis
4 Learning OutcomesCompare and contrast the light and carbon reactions of photosynthesisDescribe how light energy is converted to ATP and NADPH in the light reaction.Identify the products and reactants in the carbon reactionExplain how the products and reactants of the light and carbon reactions are linkedCompare and contrast C3, C4, and CAM plants
5 5.1 Life Depends on Photosynthesis Solar energy harnessedConverted into chemical energyAll life ultimately depends on photosynthesis
6 5.1 Life Depends on Photosynthesis A. Photosynthesis Builds Carbohydrates Out of Carbon Dioxide and WaterPigment molecules capture the sun’s energyEnergy to build glucose (C6H12O6) from carbon dioxide (CO2)Uses water and releases oxygen gas (O2)Light energy6CO2 + 6H2O → C6H12O6 + 6O2
7 5.1 Life Depends on Photosynthesis Oxidation- reduction (redox) processElectrons moved from H2O to CO2Energy from sunlightUses for glucoseHalf for plant’s own fuelManufacture other compoundsCellulose for cell wallsStore as starch or sucrose
8 5.1 Life Depends on Photosynthesis Feeds plantsProvides energy and raw materials for other organismsWaste product oxygen essential to life
10 5.1 Life Depends on Photosynthesis B. The Evolution of Photosynthesis Changed Planet EarthMost organisms rely directly or indirectly on photosynthesisFirst organisms all heterotrophsAutotrophs evolved laterPhotosynthesis release oxygen gasAerobic organisms outcompeted anaerobic organisms
12 Why is photosynthesis essential to life on Earth? 5.1 Mastering ConceptsWhy is photosynthesis essential to life on Earth?
13 5.2 Sunlight Is the Energy Source for Photosynthesis A. What is Light?Visible light part of electromagnetic spectrumPhotonsShorter wavelength = more energySunlightUltraviolet radiation, visible light, infrared radiation
15 Clicker question Which below has the MOST energy? Visible violet light Visible red lightUltraviolet radiationInfrared radiation
16 5.2 Sunlight Is the Energy Source for Photosynthesis B. Photosynthetic Pigments Capture Light EnergyPigments capture light energyChlorophyll aAccessory pigmentsAbsorb only some wavelengthsTransmit or reflect others
17 Figure 5.4 Everything but Green. If you could expose plants to just one wavelength of light at a time,would a wavelength of 300 nm, 450 nm, or 600 nm produce the highestphotosynthetic rate?
18 5.2 Sunlight Is the Energy Source for Photosynthesis C. Chloroplasts Are the Sites of PhotosynthesisLeaves are the main organ of photosynthesisCO2 and O2 enter/exit through stomataLeaf mesophyll contains chloroplasts
19 Clicker question Oxygen is a _____ of photosynthesis. waste product substrate
21 5.2 Sunlight Is the Energy Source for Photosynthesis Chloroplast structure2 membranes enclose stromaGrana composed of stack of thylakoidsThylakoid membrane studded with photosynthetic pigmentsThylakoid membrane encloses thylakoid space
23 5.2 Sunlight Is the Energy Source for Photosynthesis Chloroplast structurePhotosystemChlorophyll a aggregated with other pigment moleculesProteins anchor complex in membraneReaction centerAntenna pigments – funnel energy to reaction center
28 Clicker QuestionThe high energy molecule is?ADPAMPATPAPP
29 5.4 The Light Reactions Begin Photosynthesis 2 types of photosystemsPhotosystem IReaction center P700 – 700nmPhotosystem IIReaction center P680 – 680nmConnected by electron transport chain
30 5.4 The Light Reactions Begin Photosynthesis A. Photosystem II Produces ATPLight energy transferred to reaction centerBoosts 2 electrons from chlorophyll aPassed down electron transport systemChlorophyll a replaces electronsSplit waterOxygen waste product
31 5.4 The Light Reactions Begin Photosynthesis A. Photosystem II Produces ATPElectron transport chainEnergy drives proton active transportFrom stroma into thylakoid spaceATP synthase uses potential energyATP producedChemiosmotic phosphorylation
32 5.4 The Light Reactions Begin Photosynthesis B. Photosystem I Produces NADPHEnergy passed to reaction center2nd electron transport chainElectrons replaced from 1st electron transport chainElectrons reduce NADP+ to NADPH
33 Clicker Question Photosystem II replaces its electrons from water. oxygen.the electron transport system.NADPH.
34 5.5 The Carbon Reactions Produce Carbohydrates Also called Calvin cycleOccur in stromaUses NADPH and ATP to reduce CO2
35 5.5 The Carbon Reactions Produce Carbohydrates Carbon fixationRibulose bisphosphate (RuBP)RUBP carboxylase/oxygenase (rubisco)PGAL synthesisPGAL combined to form glucoseRuBP regenerationATP and NADPH from light reactions
36 Clicker Question Which below does NOT come out of the light reactions? GlucoseWaterNADPHATP
37 5.6 C3 Plants Use Only the Calvin Cycle to Fix Carbon C3 pathway3-carbon PGA is first stable molecule95% of plants are C3Photorespiration reduces efficiencyRubisco uses O2 instead of CO2Open stomata minimizes problemWater loss problem
38 5.7 The C4 and CAM Pathways Save Carbon and Water C4 pathwayPhysically separate light reactions and carbon reactionsLight reactions in mesophyll cellsCalvin cycle in bundle-sheath cellsUnique arrangement of cells in leaves
39 5.7 The C4 and CAM Pathways Save Carbon and Water Crassulacean acid metabolismOpen their stomata to fix CO2 only at nightFix it again in the Calvin cycle during the dayBoth fixation reactions occur in the same cell
40 Describe how a C4 plant minimizes photorespiration. 5.7 Mastering ConceptsDescribe how a C4 plant minimizes photorespiration.
41 5.8 Investigating Life: Solar-Powered Sea Slugs Sea slug Elysia chloroticaAcquire the chloroplasts by eating algaeCells lining the slug’s gut absorb the chloroplasts2 hypothesesChloroplasts autonomous – noSlug’s cells support chloroplastspsbO gene
42 5.8 Mastering ConceptsThe researchers also looked for the psbO gene in pufferfish (a vertebrate animal) and slime molds (a nonphotosynthetic protist). The gene was absent in both species. How was this finding important to the interpretation of the results of this study?