1 Photosynthesis Energy & Life copyright cmassengale

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 Energy Energy Takes Many Forms such as light, heat, electrical, chemical, mechanicalEnergy Takes Many Forms such as light, heat, electrical, chemical, mechanical Energy can be changed from one form to anotherEnergy can be changed from one form to another Energy can be stored in chemical bonds & then released laterEnergy can be stored in chemical bonds & then released later Candles release energy as HEAT & LIGHT copyright cmassengale

7 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

8 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

9 Sugar in ADP & ATP Called ribose Pentose sugar Also found on RNA copyright cmassengale

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

11 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

12 Releasing Energy From ATP Adding A Phosphate Group To ADP stores Energy in ATPAdding A Phosphate Group To ADP stores Energy in ATP Removing A Phosphate Group From ATP Releases Energy & forms ADPRemoving A Phosphate Group From ATP Releases Energy & forms ADP Loose Gain copyright cmassengale

13 Cells Using Biochemical Energy Cells Use ATP For: Active transport Movement Photosynthesis Protein Synthesis Cellular respiration All other cellular reactions copyright cmassengale

14 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

15 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

16 History of Photosynthesis & Plant Pigments copyright cmassengale

17 Photosynthesis Involves the Use Of light Energy to convert Water (H 2 0) and Carbon Dioxide (CO 2 ) into Oxygen (O 2 ) and High Energy Carbohydrates (sugars, e.g. Glucose) & StarchesInvolves the Use Of light Energy to convert Water (H 2 0) and Carbon Dioxide (CO 2 ) into Oxygen (O 2 ) and High Energy Carbohydrates (sugars, e.g. Glucose) & Starches copyright cmassengale

18 Investigating Photosynthesis Many Scientists Have Contributed To Understanding PhotosynthesisMany Scientists Have Contributed To Understanding Photosynthesis Early Research Focused On The Overall ProcessEarly Research Focused On The Overall Process Later Researchers Investigated The Detailed Chemical PathwaysLater Researchers Investigated The Detailed Chemical Pathways copyright cmassengale

19 Early Questions on Plants Several Centuries Ago, The Question Was: Does the increase in mass of a plant come from the air? The soil? The Water? copyright cmassengale

20 Van Helmont’s Experiment 1643 Planted a seed into A pre-measured amount of soil and watered for 5 yearsPlanted a seed into A pre-measured amount of soil and watered for 5 years Weighed Plant & Soil. Plant Was 75 kg, Soil The Same.Weighed Plant & Soil. Plant Was 75 kg, Soil The Same. Concluded Mass Came From WaterConcluded Mass Came From Water copyright cmassengale

21 Priestley’s Experiment 1771 Burned Candle In Bell Jar Until It Went Out. Placed Sprig Of Mint In Bell Jar For A Few Days. Candle Could Be Relit And Burn. Concluded Plants Released Substance (O 2 ) Necessary For burning. copyright cmassengale

22 Ingenhousz’s Experiment 1779 Repeated Priestly experiment with & without sunlight copyright cmassengale

23 Results of Ingenhousz’s Experiment Showed That Priestley’s Results Only Occurred In The Presence Of Sunlight.Showed That Priestley’s Results Only Occurred In The Presence Of Sunlight. Light Was Necessary For Plants To Produce The “Burning Gas” or oxygenLight Was Necessary For Plants To Produce The “Burning Gas” or oxygen copyright cmassengale

24 Julius Robert Mayer 1845 Proposed That Plants can Convert Light Energy Into Chemical Energy copyright cmassengale

25 Samuel Ruben & Martin Kamen 1941 Used Isotopes To Determine That The Oxygen Liberated In Photosynthesis Comes From Water KAMEN RUBIN copyright cmassengale

26 Melvin Calvin 1948 First to trace the path that carbon (CO 2 ) takes in forming GlucoseFirst to trace the path that carbon (CO 2 ) takes in forming Glucose Does NOT require sunlightDoes NOT require sunlight Called the Calvin Cycle or Light Independent ReactionCalled the Calvin Cycle or Light Independent Reaction Also known as the Dark ReactionAlso known as the Dark Reaction copyright cmassengale

27 Rudolph Marcus 1992 Studied the Light Independent ReactionsStudied the Light Independent Reactions First to describe the Electron transport ChainFirst to describe the Electron transport Chain copyright cmassengale

28 The Photosynthesis Equation copyright cmassengale

29 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

30 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

31 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

32 Chlorophyll There are 2 main types of chlorophyll molecules: Chlorophyll a Chlorophyll b A third type, chlorophyll c, is found in dinoflagellates Magnesium atom at the center of chlorophyll copyright cmassengale

33 Chlorophyll a and b copyright cmassengale

34 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

35 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 copyright cmassengale

36 The Biochemical Reactions copyright cmassengale

37 It Begins with Sunlight! copyright cmassengale

38 Photoautotrophs Absorb Light Energy copyright cmassengale

39 Inside A Chloroplast copyright cmassengale

40 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

41 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

42copyright cmassengale

43 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

44 Photosynthesis Overview copyright cmassengale

45 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

46 NADPH copyright cmassengale

47 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

48 Light Dependent Reaction copyright cmassengale

49 Light Dependent Reaction copyright cmassengale

50 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

51 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

52 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

53 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

54 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

55copyright cmassengale

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

57 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

58 The Calvin Cycle copyright cmassengale

59 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

60copyright cmassengale

61 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

62copyright cmassengale