Your SlideShare is downloading. ×
0
Photosynthesis powerpoint
Photosynthesis powerpoint
Photosynthesis powerpoint
Photosynthesis powerpoint
Photosynthesis powerpoint
Photosynthesis powerpoint
Photosynthesis powerpoint
Photosynthesis powerpoint
Photosynthesis powerpoint
Photosynthesis powerpoint
Photosynthesis powerpoint
Photosynthesis powerpoint
Photosynthesis powerpoint
Photosynthesis powerpoint
Photosynthesis powerpoint
Photosynthesis powerpoint
Photosynthesis powerpoint
Photosynthesis powerpoint
Photosynthesis powerpoint
Photosynthesis powerpoint
Photosynthesis powerpoint
Photosynthesis powerpoint
Photosynthesis powerpoint
Photosynthesis powerpoint
Photosynthesis powerpoint
Photosynthesis powerpoint
Photosynthesis powerpoint
Photosynthesis powerpoint
Photosynthesis powerpoint
Photosynthesis powerpoint
Photosynthesis powerpoint
Photosynthesis powerpoint
Photosynthesis powerpoint
Photosynthesis powerpoint
Photosynthesis powerpoint
Upcoming SlideShare
Loading in...5
×

Thanks for flagging this SlideShare!

Oops! An error has occurred.

×
Saving this for later? Get the SlideShare app to save on your phone or tablet. Read anywhere, anytime – even offline.
Text the download link to your phone
Standard text messaging rates apply

Photosynthesis powerpoint

512

Published on

0 Comments
1 Like
Statistics
Notes
  • Be the first to comment

No Downloads
Views
Total Views
512
On Slideshare
0
From Embeds
0
Number of Embeds
0
Actions
Shares
0
Downloads
19
Comments
0
Likes
1
Embeds 0
No embeds

Report content
Flagged as inappropriate Flag as inappropriate
Flag as inappropriate

Select your reason for flagging this presentation as inappropriate.

Cancel
No notes for slide

Transcript

  • 1. PhotosynthesisPhotosynthesis PhotosynthesisPhotosynthesis Presentation by:Presentation by: Mr M DlaminiMr M Dlamini 201221083201221083
  • 2. PhotosynthesisPhotosynthesis Photosynthesis, the biochemical process by which plants capture energy from sunlight and store it in carbohydrates.
  • 3. Autotrophic organismsAutotrophic organisms use anuse an inorganic form of carbon, e.g.inorganic form of carbon, e.g. carbon dioxidecarbon dioxide, to make up, to make up complex organic compounds, withcomplex organic compounds, with energy from two sources:energy from two sources: Rhizobium in root nodules 1) light 2) chemicals
  • 4. Photosynthetic Organisms
  • 5. PhotosynthesisPhotosynthesis Photosynthesis is more common andPhotosynthesis is more common and important because:important because: 1. It provides a source of complex organic molecules for heterotrophic organisms. 2. It releases oxygen for use by aerobic organisms.
  • 6. PhotosynthesisPhotosynthesis PhotosynthesisPhotosynthesis Photosynthesis takes place in the greenPhotosynthesis takes place in the green portions of plantsportions of plants Leaf of flowering plant contains mesophyllLeaf of flowering plant contains mesophyll tissuetissue Cells containing chloroplastsCells containing chloroplasts Specialized to carry on photosynthesisSpecialized to carry on photosynthesis COCO22 enters leaf through stomataenters leaf through stomata Diffuses into chloroplasts in mesophyll cellsDiffuses into chloroplasts in mesophyll cells In stroma, COIn stroma, CO22 combined with Hcombined with H22O to formO to form CC66HH1212OO66 (sugar)(sugar) Energy supplied by lightEnergy supplied by light
  • 7. Leaves and Photosynthesis
  • 8. PhotosynthesisPhotosynthesisPhotosynthetic Reactions:Photosynthetic Reactions: OverviewOverview Light ReactionLight Reaction:: Chlorophyll absorbs solar energyChlorophyll absorbs solar energy This energizes electronsThis energizes electrons Electrons move downElectrons move down electron transport chainelectron transport chain ­ PumpsPumps HH++ intointo thylakoidsthylakoids ­ Used to makeUsed to make ATPATP out ofout of ADPADP andand NADPHNADPH outout ofof NADPNADP Calvin Cycle ReactionCalvin Cycle Reaction COCO22 is reduced to a carbohydrateis reduced to a carbohydrate Reduction requires the ATP and NADPHReduction requires the ATP and NADPH produced aboveproduced above
  • 9. PhotosynthesisPhotosynthesis Light Dependent ReactionsLight Dependent Reactions A.A. Light absorptionLight absorption 1.1. As chlorophyll absorbs light its electronsAs chlorophyll absorbs light its electrons are raised to a higher energy level byare raised to a higher energy level by photons at certain wavelengthsphotons at certain wavelengths 2.2. The electrons at higher energy levels areThe electrons at higher energy levels are said to besaid to be excited electronsexcited electrons 3.3. The excited electrons cause theThe excited electrons cause the chlorophyll to become photoactivatedchlorophyll to become photoactivated 4.4. Photoactivation is the activation of aPhotoactivation is the activation of a particular pigment’s electrons (It isparticular pigment’s electrons (It is caused by absorbing energy fromcaused by absorbing energy from photons.)photons.)
  • 10. Photosynthesis Overview
  • 11. PhotosynthesisPhotosynthesisLight Reactions:Light Reactions: The Noncyclic Electron PathwayThe Noncyclic Electron Pathway Takes place in thylakoid membraneTakes place in thylakoid membrane Uses two photosystems,Uses two photosystems, PS-IPS-I andand PS-IIPS-II PS II captures light energyPS II captures light energy Causes an electron to be ejected from theCauses an electron to be ejected from the reactionreaction centercenter ((chlorophyllchlorophyll aa))  Electron travels down electron transport chain to PS IElectron travels down electron transport chain to PS I  Replaced with an electron from waterReplaced with an electron from water  Which causes HWhich causes H++ to concentrate in thylakoidto concentrate in thylakoid chamberschambers  Which causesWhich causes ATP productionATP production PS I captures light energy and ejects an electronPS I captures light energy and ejects an electron  TransferredTransferred permanentlypermanently to a molecule of NADPto a molecule of NADP++  CausesCauses NADPH productionNADPH production
  • 12. Light Reactions: Noncyclic Electron Pathway
  • 13. PhotosynthesisPhotosynthesisLight Reactions:Light Reactions: The Cyclic Electron PathwayThe Cyclic Electron Pathway Uses only photosystem I (PS-I)Uses only photosystem I (PS-I) Begins when PS I complex absorbs solarBegins when PS I complex absorbs solar energyenergy Electron ejected from reaction centerElectron ejected from reaction center Travels down electron transport chainTravels down electron transport chain Causes HCauses H++ to concentrate in thylakoidto concentrate in thylakoid chamberschambers Which causesWhich causes ATP productionATP production Electron returns to PS-I (cyclic)Electron returns to PS-I (cyclic) Pathway only results in ATP productionPathway only results in ATP production
  • 14. Light Reactions: Cyclic Electron Pathway
  • 15. Chapte15Light-Independent Reactions NADPH and ATP from light-NADPH and ATP from light- dependent reactions used to powerdependent reactions used to power glucose synthesisglucose synthesis Light notLight not directlydirectly necessary for light-necessary for light- independent reactions if ATP &independent reactions if ATP & NADPH availableNADPH available Light-independent reactions calledLight-independent reactions called thethe Calvin-BensonCalvin-Benson CycleCycle oror CC33 CycleCycle
  • 16. Chapte16The C3 Cycle 6 CO6 CO22 used to synthesize 1 glucoseused to synthesize 1 glucose (C(C66HH1212OO66)) Carbon dioxide is captured andCarbon dioxide is captured and linked to ribulose bisphosphatelinked to ribulose bisphosphate (RuBP)(RuBP) ATP and NADPH from lightATP and NADPH from light dependent reactions used to powerdependent reactions used to power CC33 reactionsreactions
  • 17. PhotosynthesisPhotosynthesisOrganization of theOrganization of the Thylakoid MembraneThylakoid Membrane PS IIPS II::  Pigment complex and electron-acceptorsPigment complex and electron-acceptors  Adjacent to an enzyme that oxidizes waterAdjacent to an enzyme that oxidizes water  Oxygen is released as a gasOxygen is released as a gas Electron transport chainElectron transport chain::  Consists of cytochrome complexesConsists of cytochrome complexes  Carries electrons between PS II and PS ICarries electrons between PS II and PS I  Also pump HAlso pump H++ from the stroma into thylakoid spacefrom the stroma into thylakoid space PS IPS I::  Pigment complex and electron acceptorsPigment complex and electron acceptors  Adjacent to enzyme that reduces NADPAdjacent to enzyme that reduces NADP++ to NADPHto NADPH ATP synthase complexATP synthase complex::  Has a channel for HHas a channel for H++ flowflow  Which drives ATP synthase to join ADP and PWhich drives ATP synthase to join ADP and Pii
  • 18. PhotosynthesisPhotosynthesis CC33 Cycle Has Three PartsCycle Has Three Parts 2.2. Synthesis of Glyceraldehyde 3-Synthesis of Glyceraldehyde 3- Phosphate (G3P)Phosphate (G3P)  Energy is donated by ATP and NADPHEnergy is donated by ATP and NADPH  Phosphoglyceric acid (PGA)Phosphoglyceric acid (PGA) molecules are converted intomolecules are converted into glyceraldehyde 3-Phophate (G3P)glyceraldehyde 3-Phophate (G3P) molecules …molecules … 18Ch ap ter 7
  • 19. PhotosynthesisPhotosynthesis CC33 Cycle Has Three PartsCycle Has Three Parts 3.3. Regeneration of Ribulose bis-Regeneration of Ribulose bis- phosphate (RuBP)phosphate (RuBP)  10 of 12 G3P molecules converted into10 of 12 G3P molecules converted into 6 RuBP molecules6 RuBP molecules  2 of 12 G3P molecules used to2 of 12 G3P molecules used to synthesize 1 glucosesynthesize 1 glucose  ATP energy used for these reactionsATP energy used for these reactions 19Ch ap ter 7
  • 20. PhotosynthesisPhotosynthesis A Summary of PhotosynthesisA Summary of Photosynthesis 20Ch ap ter 7 Light-Light- dependentdependent reactionsreactions occur inoccur in thylakoidsthylakoids Light-Light- independentindependent reactions (creactions (c33 cycle) occurcycle) occur in stromain stroma
  • 21. Organization of a Thylakoid
  • 22. PhotosynthesisPhotosynthesisCalvin Cycle Reactions:Calvin Cycle Reactions: Overview of C3 PhotosynthesisOverview of C3 Photosynthesis A cyclical series of reactionsA cyclical series of reactions Utilizes atmospheric carbon dioxide toUtilizes atmospheric carbon dioxide to produce carbohydratesproduce carbohydrates Known as C3 photosynthesisKnown as C3 photosynthesis Involves three stages:Involves three stages: ­Carbon dioxide fixationCarbon dioxide fixation ­Carbon dioxide reductionCarbon dioxide reduction ­RuBP RegenerationRuBP Regeneration
  • 23. PhotosynthesisPhotosynthesisCalvin Cycle Reactions:Calvin Cycle Reactions: Carbon Dioxide FixationCarbon Dioxide Fixation COCO22 is attached to 5-carbonis attached to 5-carbon RuBPRuBP moleculemolecule Result in a 6-carbon moleculeResult in a 6-carbon molecule This splits into two 3-carbon molecules (This splits into two 3-carbon molecules (3PG3PG)) Reaction accelerated byReaction accelerated by RuBPRuBP CarboxylaseCarboxylase (Rubisco)(Rubisco) COCO22 now “fixed” because it is part of anow “fixed” because it is part of a carbohydratecarbohydrate
  • 24. The Calvin Cycle: Fixation of CO2
  • 25. PhotosynthesisPhotosynthesisCalvin Cycle Reactions:Calvin Cycle Reactions: Carbon Dioxide ReductionCarbon Dioxide Reduction 3PG reduced to3PG reduced to BPGBPG BPG then reduced toBPG then reduced to G3PG3P Utilizes NADPH and some ATP produced inUtilizes NADPH and some ATP produced in light reactionslight reactions
  • 26. The Calvin Cycle Reduction of CO2 InLine Figure p125
  • 27. PhotosynthesisPhotosynthesisCalvin Cycle Reactions:Calvin Cycle Reactions: Regeneration of RuBPRegeneration of RuBP RuBP used in CORuBP used in CO22 fixation must be replacedfixation must be replaced Every three turns of Calvin Cycle,Every three turns of Calvin Cycle, Five G3P (a 3-carbon molecule) usedFive G3P (a 3-carbon molecule) used To remake three RuBP (a 5-carbon molecule)To remake three RuBP (a 5-carbon molecule) 5 X 3 = 3 X 55 X 3 = 3 X 5
  • 28. The Calvin Cycle Regeneration of RuBP
  • 29. PhotosynthesisPhotosynthesis Importance of Calvin CycleImportance of Calvin Cycle G3P (glyceraldehyde-3-phosphate) can beG3P (glyceraldehyde-3-phosphate) can be converted to many other moleculesconverted to many other molecules The hydrocarbon skeleton of G3P can formThe hydrocarbon skeleton of G3P can form Fatty acids and glycerol to make plant oilsFatty acids and glycerol to make plant oils Glucose phosphate (simple sugar)Glucose phosphate (simple sugar) Fructose (which with glucose = sucrose)Fructose (which with glucose = sucrose) Starch and celluloseStarch and cellulose Amino acidsAmino acids
  • 30. PhotosynthesisPhotosynthesis CC44 PhotosynthesisPhotosynthesis In hot, dry climatesIn hot, dry climates Stomata must close to avoid wiltingStomata must close to avoid wilting COCO22 decreases and Odecreases and O22 increasesincreases OO22 starts combining with RuBP instead of COstarts combining with RuBP instead of CO22 PhotorespirationPhotorespiration, a problem solve in C, a problem solve in C44 plantsplants In CIn C44 plantsplants Fix COFix CO22 to PEP a Cto PEP a C33 moleculemolecule The result is oxaloacetate, a CThe result is oxaloacetate, a C44 moleculemolecule In hot & dry climatesIn hot & dry climates ­ Avoid photorespirationAvoid photorespiration ­ Net productivity about 2-3 times CNet productivity about 2-3 times C33 plantsplants In cool, moist, can’t compete with CIn cool, moist, can’t compete with C
  • 31. Chloroplast distribution in C4 vs. C3 Plants
  • 32. CO2 Fixation in C4 vs. C3 Plants
  • 33. PhotosynthesisPhotosynthesis CAM PhotosynthesisCAM Photosynthesis Crassulacean-Acid MetabolismCrassulacean-Acid Metabolism CAM plants partition carbon fixation by timeCAM plants partition carbon fixation by time ­ During the nightDuring the night  CAM plants fix COCAM plants fix CO22  Forms CForms C44 molecules,molecules,  Stored in large vacuolesStored in large vacuoles ­ During daylightDuring daylight  NADPH and ATP are availableNADPH and ATP are available  Stomata closed for water conservationStomata closed for water conservation  CC44 molecules release COmolecules release CO22 to Calvin cycleto Calvin cycle
  • 34. CO2 Fixation in a CAM Plant
  • 35. Reference list http://www.slideshare.net/201221083/savedfiles?s_title=photosynth http://www.slideshare.net/201221083/savedfiles?s_title=chapter-7-p http://www.slideshare.net/201221083/savedfiles?s_title=ap-bio-ch7-

×