1 Photosynthesis Energy & Life Created by C. Massengale 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 suns energy directlyAutotrophs can use the suns energy directly Microscopic protists called 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 suns energyHeterotrophs can NOT directly use the suns 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 ATP = Adenosine TriphosphateATP = Adenosine 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 Other Cellular Energy ADP = Adenosine DiphosphateADP = Adenosine Diphosphate When cells need energy, ATP releases energy by breaking bonds with a phosphate.When cells need energy, ATP releases energy by breaking bonds with a phosphate. ADP is whats leftover ADP is whats leftover One phospha te bond has been removed 9 Sugar in ADP & ATP Called ribose Pentose (5-carbon) sugar Also found on RNA RIBOSE 10 Importance of ATP Primary 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 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: Movement Photosynthesis Cellular respiration Protein Synthesis Actively transporting large molecules across membrane 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 refreshedATP must constantly be refreshed ATP Transfers Energy Very WellATP Transfers Energy Very Well ATP Is NOT Good At Energy StorageATP Is NOT Good At Energy Storage 15 The Glucose Molecule Glucose is aGlucose is amonosaccharide (simple sugar) (simple sugar) Formula is C 6 H 12 O 6Formula is C 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 into Oxygen (O 2 ) and 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? WHAT DO YOU THINK? 20 Van Helmonts Experiment 1643 Planted a seed into a pre- measured amount of soil and watered it for 5 yearsPlanted a seed into a pre- measured amount of soil and watered it for 5 years Weighed plant & soil. Plant was 75 kg; soil mass didnt change.Weighed plant & soil. Plant was 75 kg; soil mass didnt change. Concluded mass came from waterConcluded mass came from water WHAT DO YOU THINK? 21 Priestleys Experiment 1771 Burned candle in bell jar & timed until it went out. Placed sprig of mint in bell jar for a few days. Relit candle. Burned longer with mint plant in jar. Concluded plants must release a gaseous substance necessary for burning. 22 Ingenhouszs Experiment 1779 Repeated Priestly experiment with & without sunlight, and with & without green plant 23 Results of Ingenhouszs Experiment Showed that Priestleys results only occurred in the presence of sunlight and a green plant.Showed that Priestleys results only occurred in the presence of sunlight and a green plant. Light was necessary for plants to produce the burning gasLight was necessary for plants to produce the burning gas 24 Julius Robert Mayer 1845 Proposed that plants can convert Light Energy Light Energyinto Chemical Energy 25 Samuel Ruben & Martin Kamen 1941 Used radioactive isotopes to determine that the oxygen liberated in photosynthesis comes from the water molecule KAMEN RUBIN 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 Pathway does NOT require sunlightPathway does 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 27 Rudolph Marcus 1992 Studied the Calvin Cycle (Light Independent Reactions)Studied the Calvin Cycle (Light Independent Reactions) First to describe the Electron Transport Chain as source of energyFirst to describe the Electron Transport Chain as source of energy 28 The Photosynthesis Equation 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 30 Light and Pigments Energy From The Sun Enters Earths Biosphere As Photons Photon = A unit of Light Energy Light Contains A Mixture Of Wavelengths Different Wavelengths Have Different Colors 31 Light & Pigments Different pigments absorb different wavelengths of lightDifferent pigments absorb different wavelengths of light Photons of light excite electrons in the plants pigmentsPhotons of light excite electrons in the plants pigments Excited electrons carryExcited electrons carry the absorbed energy Excited electrons leap toExcited electrons leap to HIGHER energy levels (1 level = 1 quantum leap)(1 level = 1 quantum leap) 32 Chlorophyll There are 2 main types of chlorophyll molecules: Chlorophyll a Chlorophyll b A third type, chlorophyll c, is found in microscopic dinoflagellates 33 Chlorophyll a and b Not much diff eren ce. Can you find it?? 34 Chlorophyll a Found in all plants, algae, & cyanobacteriaFound in all plants, algae, & cyanobacteria Makes photosynthesis possibleMakes photosynthesis possible Absorbs red & blue light and REFLECTS GREENAbsorbs red & blue light and REFLECTS GREEN Participates directly in the Light ReactionsParticipates directly in the Light Reactions 35 Chlorophyll b Chlorophyll b is an accessory (helper) pigmentChlorophyll b is an accessory (helper) pigment Chlorophyll b acts indirectly in photosynthesis by transferring the light energy it absorbs to chlorophyll aChlorophyll b acts indirectly in photosynthesis by transferring the light energy 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 36 The Biochemical Reactions 37 It Begins with Sunlight! 38 Photoautotrophs Absorb Light Energy 39 Inside A Chloroplast 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 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 43 Thylakoid membranes Light Dependent reactions occur hereLight Dependent reactions occur here Contain clusters of chlorophyll molecules embedded in the thylakoid membranesContain clusters of chlorophyll molecules embedded in the thylakoid membranes 44 Photosynthesis Overview 45 Energy Carriers NADP + =Nicotinamide Adenine Dinucleotide PhosphateNADP + =Nicotinamide Adenine Dinucleotide Phosphate 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 46 NADPH Amazing that a simple plant knows what to do with all of this! 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 48 Light Dependent Reaction 49 Light Dependent Reaction 50 Photosynthesis Begins Chlorophyll a & b absorb 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 Photosynthesis continues High-energy electrons are moved into chemical reactions 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 Photosynthesis continues Enzyme in thylakoid membrane called ATP Synthase As H+ ions passed through thylakoid membrane, enzyme binds them to ADP This forms ATP used for cellular respiration 53 54 Light Reaction Summary Reactants: H 2 OH 2 O Light EnergyLight Energy Energy Products: ATP ATP NADPH NADPH Dark Reaction coming up in next slides 55 Light Independent Reaction ATP & NADPH from light reactions used as batteries to supply energy for dark reactionsATP & NADPH from light reactions used as batteries to supply energy for dark reactions 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 Turns simple carbon into carbohydrates 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 each time to eventually form the 6-carbon glucose 3 CO 2 molecules enter the cycle each time to eventually form the 6-carbon glucose 58 59 Factors Affecting the Rate of Photosynthesis Amount of available waterAmount of available water TemperatureTemperature Amount of available light energyAmount of available light energy Water affects Photosynthesis Aqueous solutions are needed for many chemical reactions to occur 60 Water molecules are split to release H + and energy. This recharges the ATP/NADPH batteries Oxygen is released as waste from splitting water Enzymes in Photosynthesis Temperature effects photosynthesis for several reasons. Water cannot be used in photosynthesis reactions if it is frozen Enzymes do not function well at extreme temperatures 61 Enzyme - assisted action in photosyn thesis Light and Photosynthesis Energy to power Photosynthesis reactions depends on Hours of light energy Wavelength of light 62 Chlorophyll a & b work best in these light waves Chlorophyll a & b reflect GREEN light (thats why leaves appear green) Self-Check Quiz What two molecules are formed by plants when carbon dioxide & water are combined using sunlight as the energy? 63 64 glucose and oxygen Self-Check Quiz 65 Plants cells use light energy to make what two energy carrying molecules? Self-Check Quiz 66 ATP and NADPH Self-Check Quiz 67 Complex carbohydrates are made during what cycle of photosynthesis? Self-Check Quiz 68 Calvin Cycle AKA Light - Independent Cycle AKA The Dark Reaction Self-Check Quiz 69 Which macromolecule stores 90 times the energy of an ATP molecule? Self-Check Quiz 70 Glucose Self-Check Quiz 71 What term applies to the tiny packets of radiant energy that travel from a light source to chlorophyll? Self-Check Quiz 72 Self-Check Quiz Photons