1 Photosynthesis Energy & Life

2 Overview of Photosynthesis copyright cmassengale

3 Autotrophs Plants and some other types of organisms that contain chlorophyll are able to use light energy from the sun to produce food. copyright cmassengale

4 Autotrophs Autotrophs include organisms that make their own foodAutotrophs include organisms that make their own food Autotrophs can use the sun’s energy directlyAutotrophs can use the sun’s energy directly Euglena copyright cmassengale

5 Heterotrophs Heterotrophs are organisms that can NOT make their own foodHeterotrophs are organisms that can NOT make their own food Heterotrophs can NOT directly use the sun’s energyHeterotrophs can NOT directly use the sun’s energy copyright cmassengale

6 ATP – Cellular Energy Adenosine TriphosphateAdenosine Triphosphate Contains two, high-energy phosphate bondsContains two, high-energy phosphate bonds Also contains the nitrogen base adenine & a ribose sugarAlso contains the nitrogen base adenine & a ribose sugar copyright cmassengale

7 ADP Adenosine DiphosphateAdenosine Diphosphate ATP releases energy, a free phosphate, & ADP when cells take energy from ATPATP releases energy, a free phosphate, & ADP when cells take energy from ATP One phosphate bond has been removed copyright cmassengale

8 Importance of ATP Principal Compound Used To Store Energy In Living Organisms copyright cmassengale

9 Releasing Energy From ATP ATP is constantly being used and remade by cellsATP is constantly being used and remade by cells ATP provides all of the energy for cell activitiesATP provides all of the energy for cell activities The high energy phosphate bonds can be BROKEN to release energyThe high energy phosphate bonds can be BROKEN to release energy The process of releasing ATP’s energy & reforming the molecule is called phosphorylationThe process of releasing ATP’s energy & reforming the molecule is called phosphorylation copyright cmassengale

10 More on ATP Cells Have Enough ATP To Last For A Few SecondsCells Have Enough ATP To Last For A Few Seconds ATP must constantly be madeATP must constantly be made ATP Transfers Energy Very WellATP Transfers Energy Very Well ATP Is NOT Good At Energy StorageATP Is NOT Good At Energy Storage copyright cmassengale

11 Glucose Glucose is a monosaccharideGlucose is a monosaccharide C 6 H 12 O 6C 6 H 12 O 6 One Molecule of glucose Stores 90 Times More Chemical Energy Than One Molecule of ATPOne Molecule of glucose Stores 90 Times More Chemical Energy Than One Molecule of ATP copyright cmassengale

12 History of Photosynthesis & Plant Pigments copyright cmassengale

13 The Photosynthesis Equation copyright cmassengale

14 Pigments In addition to water, carbon dioxide, and light energy, photosynthesis requires Pigments Chlorophyll is the primary light-absorbing pigment in autotrophs Chlorophyll is found inside chloroplasts copyright cmassengale

15 Light and Pigments Energy From The Sun Enters Earth’s Biosphere As Photons Photon = Light Energy Unit Light Contains A Mixture Of Wavelengths Different Wavelengths Have Different Colors copyright cmassengale

16 Light & Pigments Different pigments absorb different wavelengths of lightDifferent pigments absorb different wavelengths of light Photons of light “excite” electrons in the plant’s pigmentsPhotons of light “excite” electrons in the plant’s pigments Excited electrons carry the absorbed energyExcited electrons carry the absorbed energy Excited electrons move to HIGHER energy levels Excited electrons move to HIGHER energy levels copyright cmassengale

17 Chlorophyll a and b copyright cmassengale

18 Chlorophyll a Found in all plants, algae, & cyanobacteriaFound in all plants, algae, & cyanobacteria Makes photosynthesis possibleMakes photosynthesis possible Participates directly in the Light ReactionsParticipates directly in the Light Reactions Can accept energy from chlorophyll bCan accept energy from chlorophyll b copyright cmassengale

19 Chlorophyll b Chlorophyll b is an accessory pigmentChlorophyll b is an accessory pigment Chlorophyll b acts indirectly in photosynthesis by transferring the light it absorbs to chlorophyll aChlorophyll b acts indirectly in photosynthesis by transferring the light it absorbs to chlorophyll a Like chlorophyll a, it absorbs red & blue light and REFLECTS GREENLike chlorophyll a, it absorbs red & blue light and REFLECTS GREEN

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21 The Biochemical Reactions

22 It Begins with Sunlight! copyright cmassengale

23 Photoautotrophs Absorb Light Energy copyright cmassengale

24 Inside A Chloroplast copyright cmassengale

25 Structure of the Chloroplast Double membrane organelleDouble membrane organelle Outer membrane smoothOuter membrane smooth Inner membrane forms stacks of connected sacs called thylakoidsInner membrane forms stacks of connected sacs called thylakoids Thylakoid stack is called the granun (grana-plural)Thylakoid stack is called the granun (grana-plural) Gel-like material around grana called stromaGel-like material around grana called stroma copyright cmassengale

26 Function of the Stroma Light Independent reactions occur hereLight Independent reactions occur here ATP used to make carbohydrates like glucoseATP used to make carbohydrates like glucose Location of the Calvin CycleLocation of the Calvin Cycle copyright cmassengale

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28 Thylakoid membranes Light Dependent reactions occur hereLight Dependent reactions occur here Photosystems are made up of clusters of chlorophyll moleculesPhotosystems are made up of clusters of chlorophyll molecules Photosystems are embedded in the thylakoid membranesPhotosystems are embedded in the thylakoid membranes The two photosystems are:The two photosystems are: Photosytem I Photosytem I Photosystem II Photosystem II copyright cmassengale

29 Photosynthesis Overview copyright cmassengale

30 Energy Carriers Nicotinamide Adenine Dinucleotide Phosphate (NADP + )Nicotinamide Adenine Dinucleotide Phosphate (NADP + ) NADP + = Reduced FormNADP + = Reduced Form Picks Up 2 high-energy electrons and H + from the Light Reaction to form NADPHPicks Up 2 high-energy electrons and H + from the Light Reaction to form NADPH NADPH carries energy to be passed on to another moleculeNADPH carries energy to be passed on to another molecule copyright cmassengale

31 NADPH copyright cmassengale

32 Occurs across the thylakoid membranesOccurs across the thylakoid membranes Uses light energyUses light energy Produce Oxygen from waterProduce Oxygen from water Convert ADP to ATPConvert ADP to ATP Also convert NADP + into the energy carrier NADPHAlso convert NADP + into the energy carrier NADPH Light Dependent Reactions copyright cmassengale

33 Light Dependent Reaction copyright cmassengale

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35 Photosystem I Discovered FirstDiscovered First Active in the final stage of the Light Dependent ReactionActive in the final stage of the Light Dependent Reaction Made of 300 molecules of ChlorophyllMade of 300 molecules of Chlorophyll Almost completely chlorophyll aAlmost completely chlorophyll a copyright cmassengale

36 Photosystem II Discovered SecondDiscovered Second Active in the beginning stage Of the Light Dependent ReactionActive in the beginning stage Of the Light Dependent Reaction Contains about equal amounts of chlorophyll a and chlorophyll bContains about equal amounts of chlorophyll a and chlorophyll b copyright cmassengale

37 Photosynthesis Begins Photosystem II absorbs light energy Electrons are energized and passed to the Electron Transport Chain Lost electrons are replaced from the splitting of water into 2H +, free electrons, and Oxygen 2H + pumped across thylakoid membrane copyright cmassengale

38 Photosystem I High-energy electrons are moved to Photosystem I through the Electron Transport Chain Energy is used to transport H + from stroma to inner thylakoid membrane NADP+ converted to NADPH when it picks up 2 electrons & H+ copyright cmassengale

39 Phosphorylation Enzyme in thylakoid membrane called ATP Synthase As H+ ions passed through thylakoid membrane, enzyme binds them to ADP Forms ATP for cellular copyright cmassengale

40 Light Reaction Summary Reactants: H 2 OH 2 O Light EnergyLight Energy Energy Products: ATPATP NADPHNADPH copyright cmassengale

41 Light Independent Reaction ATP & NADPH from light reactions used as energyATP & NADPH from light reactions used as energy Atmospheric C0 2 is used to make sugars like glucose and fructoseAtmospheric C0 2 is used to make sugars like glucose and fructose Six-carbon Sugars made during the Calvin CycleSix-carbon Sugars made during the Calvin Cycle Occurs in the stromaOccurs in the stroma copyright cmassengale

42 The Calvin Cycle copyright cmassengale

43 The Calvin Cycle Two turns of the Calvin Cycle are required to make one molecule of glucoseTwo turns of the Calvin Cycle are required to make one molecule of glucose 3-CO 2 molecules enter the cycle to form several intermediate compounds (PGA)3-CO 2 molecules enter the cycle to form several intermediate compounds (PGA) A 3-carbon molecule called Ribulose Biphosphate (RuBP) is used to regenerate the Calvin cycleA 3-carbon molecule called Ribulose Biphosphate (RuBP) is used to regenerate the Calvin cycle copyright cmassengale

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45 Factors Affecting the Rate of Photosynthesis Amount of available waterAmount of available water TemperatureTemperature Amount of available light energyAmount of available light energy copyright cmassengale

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