1 Photosynthesis Energy & Life

2 Overview of Photosynthesis

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

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

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

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

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

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

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

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

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

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 Lose Gain

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

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

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

16 History of Photosynthesis & Plant Pigments

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

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

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?

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

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.

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

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

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

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

26 The Photosynthesis Equation

27 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

28 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

29 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 LinkLinkLink

30 Chlorophyll There are 2 main types of chlorophyll molecules: Chlorophyll a Chlorophyll b Magnesium atom at the center of chlorophyll

31 Chlorophyll a and b

32 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

33 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

34 The Biochemical Reactions

35 It Begins with Sunlight!

36 Photoautotrophs Absorb Light Energy

37 Inside A Chloroplast

38 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 granum (grana-plural)Thylakoid stack is called the granum (grana-plural) Gel-like material around grana called stromaGel-like material around grana called stroma

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40 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

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

42 Photosynthesis Overview

43 Energy Carriers Nicotinamide Adenine Dinucleotide Phosphate (NADP + )Nicotinamide Adenine Dinucleotide Phosphate (NADP + ) 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

44 NADPH

45 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

46 Light Dependent Reaction

47 Light Dependent Reaction

48 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

49 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

50 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

51 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+

52 Phosphorylation Enzyme in thylakoid membrane called ATP Synthetase As H+ ions passed through thylakoid membrane, enzyme binds them to ADP Forms ATP for cellular

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54 Light Reaction Summary Reactants: H 2 OH 2 O Light EnergyLight Energy Energy Products: ATPATP NADPHNADPH Other Product: OxygenOxygen

55 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

56 The Calvin Cycle

57 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

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59 Factors Affecting the Rate of Photosynthesis Amount of available waterAmount of available water TemperatureTemperature Amount of available light energyAmount of available light energy

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