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Photosynthesis ppt by Lalit Kumar


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Photosynthesis is a major process which all should know. For this only this ppt has been made to understand the basics as well as more about it . It will help all students in their project submission. Hope find well.

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Photosynthesis ppt by Lalit Kumar

  2. 2. * PhotosynthesisPhotosynthesis • AnabolicAnabolic (small molecules combined)(small molecules combined) • EndergonicEndergonic (stores energy)(stores energy) • Carbon dioxide (COCarbon dioxide (CO22)) requiring processrequiring process that usesthat uses light energy (photons)light energy (photons) andand water (Hwater (H22O)O) to produceto produce organicorganic macromolecules (glucose).macromolecules (glucose). 6CO2 + 6H2O → C6H12O6 + 6O2glucoseglucose SUN photonsphotons
  3. 3. * Question:Question: Where doesWhere does photosynthesisphotosynthesis take place?take place?
  4. 4. * PlantsPlants • AutotrophsAutotrophs – produce their own food– produce their own food (glucose)(glucose) • Process calledProcess called photosynthesisphotosynthesis • Mainly occurs in theMainly occurs in the leaves:leaves: a.a. stoma - poresstoma - pores b.b. mesophyll cellsmesophyll cells Stoma Mesophyll Cell Chloroplast
  5. 5. * Stomata (stoma)Stomata (stoma) PoresPores in a plant’s cuticle throughin a plant’s cuticle through whichwhich water vaporwater vapor andand gasesgases (CO(CO22 & O& O22)) are exchanged between theare exchanged between the plant and the atmosphere.plant and the atmosphere. Guard CellGuard Cell Carbon Dioxide (CO2) Oxygen (O2) Found on the underside of leavesFound on the underside of leaves StomaStoma
  6. 6. * Mesophyll Cell of LeafMesophyll Cell of Leaf Cell Wall NucleusNucleus Chloroplast Central Vacuole Photosynthesis occurs in these cells!Photosynthesis occurs in these cells!
  7. 7. * ChloroplastChloroplast OrganelleOrganelle where photosynthesisphotosynthesis takes place. GranumThylakoid Stroma Outer Membrane Inner Membrane Thylakoid stacks are connected togetherThylakoid stacks are connected together
  8. 8. * ThylakoidThylakoid Thylakoid Membrane Thylakoid Space Granum Grana make up the inner membraneGrana make up the inner membrane
  9. 9. * Question:Question: Why areWhy are plantsplants green?green?
  10. 10. * Chlorophyll MoleculesChlorophyll Molecules • Located in theLocated in the thylakoid membranesthylakoid membranes • Chlorophyll haveChlorophyll have MgMg++ in the centerin the center • Chlorophyll pigmentsChlorophyll pigments harvest energyharvest energy (photons)(photons) by absorbing certainby absorbing certain wavelengthswavelengths (blue-420 nm and red-(blue-420 nm and red- 660 nm660 nm are most important)are most important) • Plants arePlants are greengreen because thebecause the greengreen wavelength is reflectedwavelength is reflected, not absorbed, not absorbed.
  11. 11. *
  12. 12. * Wavelength of Light (nm)Wavelength of Light (nm) 400 500 600 700 Short wave Long wave (more energy) (less energy)
  13. 13. * Absorption of Light byAbsorption of Light by ChlorophyllChlorophyll wavelengthwavelength Absorption violet blue green yellow orange red Chlorophyll absorbs blue-violet & red light bestChlorophyll absorbs blue-violet & red light best
  14. 14. * Question:Question: During the fall,During the fall, what causes thewhat causes the leaves to changeleaves to change colors?colors?
  15. 15. * Fall ColorsFall Colors • In addition to the chlorophyllIn addition to the chlorophyll pigments, there arepigments, there are other pigmentsother pigments presentpresent • During the fall, theDuring the fall, the greengreen chlorophyll pigments are greatlychlorophyll pigments are greatly reducedreduced revealing the other pigmentsrevealing the other pigments • CarotenoidsCarotenoids are pigments that areare pigments that are eithereither redred,, orangeorange, or, or yellowyellow
  16. 16. * Redox ReactionRedox Reaction TheThe transfertransfer of one or moreof one or more electronselectrons from one reactant tofrom one reactant to anotheranother Two types:Two types: 1.1. Oxidation is theOxidation is the lossloss of eof e-- 2.2. Reduction is theReduction is the gaingain of eof e--
  17. 17. * Oxidation ReactionOxidation Reaction TheThe loss of electronsloss of electrons from afrom a substance or thesubstance or the gain ofgain of oxygen.oxygen. glucoseglucose 6CO2 + 6H2O → C6H12O6 + 6O2 OxidationOxidation CarbonCarbon dioxidedioxide WaterWater OxygenOxygen
  18. 18. * Reduction ReactionReduction Reaction TheThe gain of electronsgain of electrons to ato a substance or thesubstance or the loss ofloss of oxygen.oxygen. glucoseglucose 6CO2 + 6H2O → C6H12O6 + 6O2 ReductionReduction
  19. 19. * Question:Question: Why do cellsWhy do cells use foruse for energy?energy?
  20. 20. * Energy for Life on EarthEnergy for Life on Earth • Sunlight is the ULTIMATE energy for all life on Earth • Plants store energy in the chemical bonds of sugars • Chemical energy is released as ATP during cellular respiration
  21. 21. * Structure of ATPStructure of ATP • ATP stands for adenosine triphosphate • It is composed of the nitrogen base ADENINE, the pentose (5C) sugar RIBOSE, and three PHOSPHATE groups • The LAST phosphate group is bonded with a HIGH ENERGY chemical bond • This bond can be BROKEN to release ENERGY for CELLS to use
  22. 22. * Removing a Phosphate from ATPRemoving a Phosphate from ATP Breaking the LAST PHOSPHATE bond from ATP, will --- – Release ENERGY for cells to use – Form ADP – Produce a FREE PHOSPHATE GROUP
  23. 23. * High Energy Phosphate BondHigh Energy Phosphate Bond
  24. 24. * FREE PHOSPHATE can be re-attached toFREE PHOSPHATE can be re-attached to ADP reforming ATPADP reforming ATP Process calledProcess called PhosphorylationPhosphorylation
  25. 25. * PhosphorylationPhosphorylation
  26. 26. * Parts ofParts of PhotosynthesisPhotosynthesis
  27. 27. * Two Parts of PhotosynthesisTwo Parts of Photosynthesis Two reactions make upTwo reactions make up photosynthesis:photosynthesis: 1.1.Light Reaction or LightLight Reaction or Light Dependent ReactionDependent Reaction -- Produces energy from solarProduces energy from solar power (photons) in the form ofpower (photons) in the form of ATP and NADPH.ATP and NADPH. SUNSUN
  28. 28. * Two Parts of PhotosynthesisTwo Parts of Photosynthesis 2.2. Calvin Cycle or LightCalvin Cycle or Light IndependentIndependent ReactionReaction • Also calledAlso called Carbon FixationCarbon Fixation oror CC33 FixationFixation • Uses energy (Uses energy (ATP andATP and NADPHNADPH) from light reaction) from light reaction to make sugarto make sugar (glucose).(glucose).
  29. 29. * Light Reaction (Electron Flow)Light Reaction (Electron Flow) • Occurs in theOccurs in the ThylakoidThylakoid membranesmembranes • During theDuring the light reactionlight reaction, there, there areare twotwo possible routes forpossible routes for electron flow:electron flow: A.A.Cyclic Electron FlowCyclic Electron Flow B.B. Noncyclic Electron FlowNoncyclic Electron Flow
  30. 30. * Cyclic Electron FlowCyclic Electron Flow • Occurs in theOccurs in the thylakoidthylakoid membrane.membrane. • UsesUses Photosystem I onlyPhotosystem I only • P700P700 reaction center- chlorophyll areaction center- chlorophyll a • Uses Electron Transport ChainUses Electron Transport Chain (ETC)(ETC) • GeneratesGenerates ATP onlyATP only ADP +ADP + ATPATP P
  31. 31. * Cyclic Electron FlowCyclic Electron Flow P700 Primary Electron Acceptor e- e- e- e- ATPATP produced by ETC Photosystem I Accessory Pigments SUN Photons Pigments absorb light energy & excite e- ofPigments absorb light energy & excite e- of Chlorophyll a to produce ATPChlorophyll a to produce ATP
  32. 32. * Noncyclic Electron FlowNoncyclic Electron Flow • Occurs in theOccurs in the thylakoidthylakoid membranemembrane • UsesUses Photosystem IIPhotosystem II andand Photosystem IPhotosystem I • P680P680 reaction centerreaction center (PSII)(PSII) -- chlorophyll achlorophyll a • P700P700 reaction centerreaction center (PS I)(PS I) -- chlorophyll achlorophyll a • Uses Electron Transport ChainUses Electron Transport Chain (ETC)(ETC) • GeneratesGenerates OO22, ATP and NADPH, ATP and NADPH
  33. 33. * Noncyclic Electron FlowNoncyclic Electron Flow P700 Photosystem I P680 Photosystem II Primary Electron Acceptor Primary Electron Acceptor ETC Enzyme Reaction H2O 1/2O1/2O22 + 2H+ ATPATP NADPHNADPH Photon 2e- 2e- 2e- 2e- 2e- SUN Photon HH22O is split in PSII & ATP is made, while the energy carrierO is split in PSII & ATP is made, while the energy carrier NADPH is made in PSINADPH is made in PSI
  34. 34. * Noncyclic Electron FlowNoncyclic Electron Flow • ADP +ADP + →→ ATPATP • NADPNADP++ + H+ H →→ NADPHNADPH • OxygenOxygen comes from the splittingcomes from the splitting of Hof H22O, not COO, not CO22 HH22OO →→ 1/2 O1/2 O22 + 2H+ 2H++ PP
  35. 35. * ChemiosmosisChemiosmosis • PowersPowers ATP synthesisATP synthesis • Takes place across the thylakoidTakes place across the thylakoid membranemembrane • UsesUses ETCETC andand ATP synthaseATP synthase (enzyme)(enzyme) • H+H+ move down their concentrationmove down their concentration gradient throughgradient through channels of ATPchannels of ATP synthasesynthase formingforming ATP from ADPATP from ADP
  36. 36. * ChemiosmosisChemiosmosis H+ H+ ATP Synthase H+ H+ H+ H+ H+ H+ high Hhigh H++ concentrationconcentration H+ ADP + P ATP PS II PS I E T C low Hlow H++ concentrationconcentration H+ ThylakoidThylakoid SpaceSpace ThylakoidThylakoid SUN (Proton Pumping)
  37. 37. * Calvin CycleCalvin Cycle • Carbon FixationCarbon Fixation (light independent(light independent reaction)reaction) • CC33 plants (80% of plants on earth)plants (80% of plants on earth) • Occurs in theOccurs in the stromastroma • UsesUses ATP and NADPHATP and NADPH from lightfrom light reaction as energyreaction as energy • UsesUses COCO22 • To produceTo produce glucoseglucose: it takes: it takes 66 turns and uses 18 ATP and 12turns and uses 18 ATP and 12 NADPH.NADPH.
  38. 38. * ChloroplastChloroplast GranumThylakoid STROMA– where Calvin Cycle occurs Outer Membrane Inner Membrane
  39. 39. * Calvin Cycle (CCalvin Cycle (C33 fixation)fixation) 6CO2 6C-C-C-C-C-C 6C-C-C 6C-C-C 6C-C-C-C-C 12PGA RuBP 12G3P (unstable) 6NADPH 6NADPH 6ATP 6ATP 6ATP C-C-C-C-C-C Glucose (6C) (36C) (36C) (36C) (30C) (30C) (6C) 6C-C-C 6C-C-C C3 glucose
  40. 40. * Calvin CycleCalvin Cycle Remember: CRemember: C33 = Calvin Cycle= Calvin Cycle C3 Glucose
  41. 41. * PhotorespirationPhotorespiration • Occurs on hot, dry, bright daysOccurs on hot, dry, bright days • Stomates closeStomates close • Fixation of OFixation of O22 instead of COinstead of CO22 • ProducesProduces 2-C molecules instead of2-C molecules instead of 3-C sugar molecules3-C sugar molecules • ProducesProduces no sugarno sugar molecules ormolecules or nono ATPATP
  42. 42. * PhotorespirationPhotorespiration Because of photorespiration, plantsBecause of photorespiration, plants have special adaptations to limithave special adaptations to limit the effect of photorespiration:the effect of photorespiration: 1.1. CC44 plantsplants 2.2. CAM plantsCAM plants
  43. 43. * CC44 PlantsPlants • Hot, moistHot, moist environmentsenvironments • 15% of plants15% of plants ((grasses, corn,grasses, corn, sugarcane)sugarcane) • PhotosynthesisPhotosynthesis occurs in 2 placesoccurs in 2 places • Light reactionLight reaction -- mesophyll cellsmesophyll cells • Calvin cycleCalvin cycle - bundle- bundle sheath cellssheath cells
  44. 44. * CC44 PlantsPlants Mesophyll CellMesophyll Cell CO2 C-C-C PEP C-C-C-C Malate-4C sugar ATP Bundle Sheath CellBundle Sheath Cell C-C-C Pyruvic Acid C-C-C-C CO2 C3 Malate Transported glucose Vascul Tissu
  45. 45. * CAM PlantsCAM Plants • Hot, dry environmentsHot, dry environments • 5%5% of plants (cactus and iceof plants (cactus and ice plants)plants) • Stomates closed during dayStomates closed during day • Stomates open during the nightStomates open during the night • Light reaction - occurs duringLight reaction - occurs during the daythe day • Calvin Cycle - occurs when COCalvin Cycle - occurs when CO22 isis presentpresent
  46. 46. * CAM PlantsCAM Plants Night (Stomates Open) Day (Stomates Closed) Vacuole C-C-C-C Malate C-C-C-C Malate Malate C-C-C-C CO2 CO2 C3 C-C-C Pyruvic acid ATP C-C-C PEP glucose
  47. 47. * Question:Question: Why do CAMWhy do CAM plants closeplants close their stomatatheir stomata during the day?during the day?
  48. 48. Cam plants closeCam plants close their stomata intheir stomata in the hottest partthe hottest part of the day toof the day to conserve waterconserve water