ap bio ch7 power point2229
TRANSCRIPT
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ChapterChapter 7
PhotosynthesisPhotosynthesis
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Chapter 72
What Is Photosynthesis?What Is Photosynthesis?
Early cells evolved the abilityEarly cells evolved the abilityto perform photosynthesisto perform photosynthesisabout 2 billion years agoabout 2 billion years ago
PhotosynthesisPhotosynthesis is the ability tois the ability tocapture sunlight energy andcapture sunlight energy andconvert it to chemical energyconvert it to chemical energy
Most forms of life on EarthMost forms of life on Earthdepend on the chemicaldepend on the chemicalenergy produced byenergy produced by
photosynthetic organismsphotosynthetic organisms
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Chapter 73
The PhotosyntheticThe PhotosyntheticEquationEquation
6CO2
carbon
dioxide
+ 6H2O
water
+ light energysunlight
C6H12O6glucose
(sugar)
+ 6O2oxygen
Photosynthesis occurs in plants,Photosynthesis occurs in plants,algae, andalgae, and some prokaryotessome prokaryotes
Photosynthetic organisms arePhotosynthetic organisms areautotrophsautotrophs (self-(self- feeders)feeders)Photosynthesis in plants occursPhotosynthesis in plants occurswithinwithin chloroplastschloroplasts
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Chapter 74
Gases, Sugar, andGases, Sugar, andWater CycleWater CycleProduction of carbonProduction of carbon
compounds like glucosecompounds like glucose
(photosynthesis) is linked(photosynthesis) is linkedwith energy extraction (inwith energy extraction (incellular respiration)cellular respiration)
Water, COWater, CO22, sugar, and O, sugar, and O22
cycle between the twocycle between the twoprocessesprocesses
Photosynthesis and cellularPhotosynthesis and cellular
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Chapter 75
Photosynthesis &Photosynthesis &RespirationRespiration
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Chapter 76
Adaptations forAdaptations forPhotosynthesisPhotosynthesis
LeavesLeaves
ChloroplastsChloroplasts
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Chapter 77
Structures ofStructures ofPhotosynthesisPhotosynthesis
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Chapter 78
LeavesLeavesFlattened leaf shapeFlattened leaf shape
exposes large surface areaexposes large surface areato catch sunlightto catch sunlight
Upper and lower leafUpper and lower leaf
surfaces of a leaf comprisesurfaces of a leaf comprisethethe epidermisepidermis
Waxy, waterproofWaxy, waterproofcuticlecuticle onon
outer surfaces reducesouter surfaces reduceswater evaporationwater evaporation
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Chapter 79
Leaf AnatomyLeaf AnatomyAdjustable pores calledAdjustable pores calledstomatastomata allow for entry ofallow for entry ofair with COair with CO22
InnerInner mesophyllmesophyll cell layerscell layerscontain majority ofcontain majority ofchloroplastschloroplasts
Vascular bundlesVascular bundles (veins)(veins)supply water and mineralssupply water and mineralsto the leaf while carryingto the leaf while carrying
sugars away from the leafsugars away from the leaf
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Chapter 710
Internal Leaf StructureInternal Leaf Structure
Internal leaf structure isInternal leaf structure is
crucial to photosynthesiscrucial to photosynthesissince photosynthesissince photosynthesisoccurs primarily in theoccurs primarily in the
leaves of land plansleaves of land plans
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Chapter 711
Leaf StructureLeaf Structure
MesophylMesophylCellCell
MesophylMesophylCellCell
Upper EpidermisUpper EpidermisUpper EpidermisUpper Epidermis
LoweLowe
EpidermiEpidermi
LoweLowe
EpidermiEpidermiVeinVeinVeinVein StomaStomaStomaStoma
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Chapter 712
Anatomy of a ChloroplasAnatomy of a Chloroplas
Mesophyll cells have 40-Mesophyll cells have 40-
200 chloroplasts each200 chloroplasts eachChloroplasts are boundedChloroplasts are boundedby a double membraneby a double membrane
composed of thecomposed of the innerinner andandouter membranesouter membranes
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Chapter 713
Anatomy of a ChloroplastAnatomy of a Chloroplast
TheThe stromastroma is the semi-fluidis the semi-fluidmedium within the innermedium within the innermembranemembrane
Disk-shaped sacs calledDisk-shaped sacs calledthylakoidsthylakoids found within thefound within thestroma in stacks calledstroma in stacks calledgranagrana
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Chapter 714
Chloroplast StructureChloroplast Structure
Inner & OuterInner & Outer
MembranesMembranes
ThylakoidsThylakoids
GranumGranum
StromaStroma(space)(space)
Th E i Vi iblTh E i Vi ibl
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Chapter 715
The Energy in VisibleThe Energy in VisibleLightLightThe sun radiatesThe sun radiates
electromagnetic energyelectromagnetic energyVisible light is radiationVisible light is radiationfalling between 400-750falling between 400-750
nanometers of wavelengthnanometers of wavelengthPackets of energy calledPackets of energy calledphotonsphotons with different energywith different energy
levelslevelsShort-wavelength photonsShort-wavelength photonsare very energeticare very energetic
Lon er-wavelen th hotonsLon er-wavelen th hotons
16
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Chapter 716
Light, ChloroplastLight, ChloroplastPigments, & PhotosynthesisPigments, & Photosynthesis
Gamma RaysGamma Rays X-RaysX-RaysUVUV InfraredInfraredMicro-Micro-waveswaves RadioRadioWavesWaves
Visible LightVisible Light
400400 450450 500500 550550 600600 650650 700700 7575
Wavelength (nanometers, nm)Wavelength (nanometers, nm)
17Li ht C t d bLi ht C t d b
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Chapter 717
Light Captured byLight Captured byPigmentsPigments
Action of light-capturingAction of light-capturingpigmentspigmentsAbsorptionAbsorption of certainof certain
wavelengths (light iswavelengths (light istrapped)trapped)ReflectionReflection of certainof certain
wavelengths (lightwavelengths (lightbounces back)bounces back)TransmissionTransmission of certainof certain
wavelengths (lightwavelengths (light
18Li ht C t d bLi ht C t d b
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Chapter 718
Light Captured byLight Captured byPigmentsPigments
Absorbed light drivesAbsorbed light drivesbiological processes whenbiological processes whenit is converted to chemicalit is converted to chemicalenergyenergy
Common pigments found inCommon pigments found inchloroplasts include:chloroplasts include:ChlorophyllChlorophyllaaandandbbAccessory pigments suchAccessory pigments such
asas carotenoidscarotenoids
h 19
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Chapter 719Light Captured byLight Captured by
PigmentsPigmentsChlorophyll a and bChlorophyll a and b absorbabsorb
violet, blue, and red lightviolet, blue, and red lightbut reflect green lightbut reflect green light(hence they appear green)(hence they appear green)
CarotenoidsCarotenoids absorb blue andabsorb blue andgreen light but reflectgreen light but reflectyellow, orange, or redyellow, orange, or red
(hence they appear yellow-(hence they appear yellow-orange)orange)
Pigment absorbs visiblePigment absorbs visible
lightlight
Ch 720
Absorption SpectraA sorpt on Spectra
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Chapter 720
00
2020
4040
6060
8080
100100
%L
ight
Absorption
%L
ight
Absorption
0000 450450 500500 550550 600600 650650 700700 750750
Wavelength (nanometers)Wavelength (nanometers)
0000 450450 500500 550550 600600 650650 700700 750750
Absorption SpectraA sorpt on Spectra
Visible LightVisible Light
ChlorophyllChlorophyll
CarotenoidsCarotenoids
PhycocyaPhycocyaninnin
CollectivCollectivelyely
Chapter7 7Light, ChloroplastLight, ChloroplastPigments &PhotosynthesisPigments &Photosynthesis
GammaRaysGammaRays XX--RaysRaysUVUV InfraredInfraredMicroMicro--waveswavesRadioRadioWavesWaves
VisibleLightVisibleLight
777777 777777 777777 777777 777777 777777 777777 777777
Wavelength(nanometers)Wavelength(nanometers)
Ch t 721O i f
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Chapter 721
GlucoseGlucose
OO22
Overview ofOverview ofPhotosynthesisPhotosynthesis
Light-DependentLight-DependentReactionsReactions
(in thylakoids)(in thylakoids)
Light-IndependentLight-IndependentReactionsReactions
(in stroma)(in stroma)
DepleteDepletedd
CarriersCarriers(ADP,(ADP,
NADPNADP++))
DepleteDepletedd
CarriersCarriers
(ADP,(ADP,
NADPNADP++))
EnergizEnergizeded
CarriersCarriers
(ATP,(ATP,
NADPH)NADPH)
HH22OO
CC
OO22
Ch t 722
The PhotosystemsThe Photosystems
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Chapter 722
The PhotosystemsThe Photosystems
Ch t 723Li ht DependentLight Dependent
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Chapter 723
Light-DependentLight-DependentReactionsReactions
Steps of the light reactions:Steps of the light reactions:
Accessory pigments inAccessory pigments in
Photosystems absorbPhotosystems absorblight and pass energy tolight and pass energy toreaction centersreaction centers containingcontaining
chlorophyllchlorophyllReaction centers receiveReaction centers receive
energized electronsenergized electrons
Ch t 724Light DependentLight Dependent
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Chapter 724
Light-DependentLight-DependentReactionsReactionsEnergized electrons thenEnergized electrons then
passed down a series ofpassed down a series ofelectron carrierelectron carriermolecules (molecules (ElectronElectron
Transport ChainTransport Chain))Energy released fromEnergy released from
passed electrons used topassed electrons used to
synthesizesynthesize ATPATP from ADPfrom ADPand phosphateand phosphate
Energized electrons alsoEnergized electrons also
used to makeused to make NADPHNADPH fromfrom
Ch t 725
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Chapter 725
Thylakoid Structure &Thylakoid Structure &Light-Dependent ReactionsLight-Dependent Reactions
Ch t 726
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Chapter 726
Oxygen as a By-productOxygen as a By-product
Chapter 727
ChemiosmosiChemiosmosi
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Chapter 727
ChemiosmosiChemiosmosis 1s 1
Chapter 728
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Chapter 728
ChemiosmosChemiosmosis 2is 2
Chapter 729LightLight InIndependentdependent
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Chapter 729
Light-Light-InIndependentdependentReactionsReactions
NADPH and ATP from light-NADPH and ATP from light-dependent reactions useddependent reactions usedto power glucose synthesisto power glucose synthesis
Light notLight not directlydirectlynecessarynecessaryfor light-independentfor light-independentreactions if ATP & NADPHreactions if ATP & NADPH
availableavailableLight-independent reactionsLight-independent reactionscalled thecalled the Calvin-BensonCalvin-Benson
CycleCycle oror CC33 CycleCycle
Chapter 730
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Chapter 730The CThe C33 CycleCycle
6 CO6 CO22 used to synthesize 1used to synthesize 1glucose (Cglucose (C66HH1212OO66))
Carbon dioxide is capturedCarbon dioxide is captured
and linked to ribuloseand linked to ribulosebisphosphate (RuBP)bisphosphate (RuBP)
ATP and NADPH from lightATP and NADPH from light
dependent reactions useddependent reactions usedto power Cto power C33 reactionsreactions
Chapter 731
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Chapter 731CC33 Cycle Has Three PartsCycle Has Three Parts
1. Carbon fixation (carbon1. Carbon fixation (carboncapture)capture)
6 Ribulose bisphosphate6 Ribulose bisphosphate(RuBP) molecules combine(RuBP) molecules combinewith 6COwith 6CO22
Fixation step andFixation step andsubsequent reactions yieldsubsequent reactions yield
twelve 3-carbontwelve 3-carbonphosphoglyceric acid (PGA)phosphoglyceric acid (PGA)moleculesmolecules
Chapter 732
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Chapter 732CC33 Cycle Has Three PartsCycle Has Three Parts
2. Synthesis of2. Synthesis ofGlyceraldehyde 3-Glyceraldehyde 3-Phosphate (G3P)Phosphate (G3P)
Energy is donated by ATPEnergy is donated by ATPand NADPHand NADPH
Phosphoglyceric acid (PGA)Phosphoglyceric acid (PGA)molecules are convertedmolecules are converted
into glyceraldehyde 3-into glyceraldehyde 3-Phophate (G3P) moleculesPhophate (G3P) molecules
Chapter 733
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Chapter 733CC33 Cycle Has Three PartsCycle Has Three Parts
3. Regeneration of3. Regeneration ofRibulose bis-phosphateRibulose bis-phosphate(RuBP)(RuBP)
10 of 12 G3P molecules10 of 12 G3P moleculesconverted into 6 RuBPconverted into 6 RuBPmoleculesmolecules
2 of 12 G3P molecules used2 of 12 G3P molecules usedto synthesize 1 glucoseto synthesize 1 glucose ATP energy used for theseATP energy used for these
reactionsreactions
Chapter 734
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Chapter 734The CThe C33
Cycle ofCycle of
CarbonCarbonFixationFixationoror
DarkDarkReactionsReactionsororLight-Light-
IndependeIndependentntReactionsReactions
oror
Chapter 735Relationship BetweenRelationship Between
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Chapter 735
Relationship BetweenRelationship BetweenReactionsReactions
The photo part ofThe photo part ofphotosynthesis refers tophotosynthesis refers to
the capture of light energythe capture of light energy(light dependent(light dependentreactions)reactions)
The synthesis part ofThe synthesis part ofphotosynthesis refers tophotosynthesis refers toglucose synthesis (light-glucose synthesis (light-
inindependent reactions)dependent reactions)
Chapter 736Relationship BetweenRelationship Between
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Chapter 736
Relationship BetweenRelationship BetweenReactionsReactions
Light dependent reactionsLight dependent reactionsproduce ATP and NADPHproduce ATP and NADPH
which is used to drivewhich is used to drivelight-independentlight-independentreactionsreactions
Depleted carriers (ADP andDepleted carriers (ADP andNADPNADP++) return to light-) return to light-dependent reactions fordependent reactions for
rechargingrecharging
Chapter 737A Summary ofA Summary of
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Chapter 737
A Summary ofA Summary ofPhotosynthesisPhotosynthesis
Light-Light-
dependentdependentreactionsreactionsoccur inoccur in
thylakoidsthylakoids
Light-Light-independeindependentnt
reactionsreactions(c(c33 cycle)cycle)
occur inoccur instromastroma
Chapter 738atera er 22 an t ean e 44
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Chapter 738
ater,a er, 22, an t e, an e 44PathwayPathwayThe ideal leaf:The ideal leaf:
has large surface area tohas large surface area tointercept sunlightintercept sunlight
are porous to allow for COare porous to allow for CO22
entry from airentry from airProblem: Substantial leafProblem: Substantial leafporosity leads to substantialporosity leads to substantial
water evaporation, causingwater evaporation, causingdehydration stress on the plantdehydration stress on the plant
Plants evolved waterproofPlants evolved waterproofcoating and adjustable porescoating and adjustable pores(stomata) for CO(stomata) for CO2 entrentry
Chapter 739
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Chapter 739
When Stomata Are CloseWhen Stomata Are CloseWhen stomata close, COWhen stomata close, CO22 levelslevels
drop and Odrop and O22 levels riselevels riseCarbon fixing enzyme combines OCarbon fixing enzyme combines O22instead of COinstead of CO22 with RuBP (calledwith RuBP (called
photorespirationphotorespiration))Photorespiration:Photorespiration:OO22 is used up as COis used up as CO22 isisgeneratedgenerated
No useful cellular energy madeNo useful cellular energy madeNo glucose producedNo glucose producedPhotorespiration isPhotorespiration isun roductive and wastefulunproductive and wasteful
Chapter 740
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Chapter 740
When Stomata Are ClosedWhen Stomata Are Closed
Hot, dry weather causesHot, dry weather causesstomata to stay closedstomata to stay closed
Oxygen levels rise as carbonOxygen levels rise as carbondioxide levels fall inside leafdioxide levels fall inside leaf
Photorespiration veryPhotorespiration very
common under suchcommon under suchconditionsconditions
Plants may die from lack ofPlants may die from lack of
glucose synthesisglucose synthesis Chapter 74144 ants e ucean s e uce
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Chapter 741
44 ants e ucean s e ucePhotorespirationPhotorespiration
CC44 plants have chloroplastsplants have chloroplasts
in bundle sheath cells as wellin bundle sheath cells as well
as mesophyll cellsas mesophyll cellsBundle sheath cellsBundle sheath cellssurround vascular bundlessurround vascular bundles
deep within mesophylldeep within mesophyllCC33 plants lack bundleplants lack bundle
sheath cell chloroplastssheath cell chloroplasts
Chapter 742
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Chapter 742CC33 Plants & the PathwayPlants & the Pathway
CC33
plants useplants usethe Cthe C33 pathwaypathway
In a CIn a C33 plant,plant,mostmost
chloroplasts arechloroplasts are
in mesophyllin mesophyll
Chapter 743
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Chapter 743CC33 Plants & the PathwayPlants & the Pathway
MuchMuchphotorespiratiophotorespiration occurs undern occurs under
hot, dryhot, dryconditionsconditions
Chapter 744CC44 Plants & the CPlants & the C44
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Chapter 744
CC44 Plants & the CPlants & the C44PathwayPathway
CC44
plants useplants usethe Cthe C44 pathwaypathway
In a CIn a C44 plant,plant,both mesophyllboth mesophyll& bundle-sheath& bundle-sheath
cells containcells contain
Chapter 745COCO ii
Mesophyll cell in a CMesophyll cell in a C44 plantplant
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Chapter 745
CC44 PlantsPlants& the C& the C44PathwayPathway
Almost noAlmost nophotorespiratiphotorespirati
on occurson occursunder hot, dryunder hot, dry
conditions.conditions.
COCO22 isiscapturedcaptured
with a highlywith a highly
specificspecificenzyme.enzyme.
MuchMuchglucoseglucose
synthesissynthesis
occurs.occurs.
p yp y pp
Bundle-sheath cell in a CBundle-sheath cell in a C44
Ch tCh t 7
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ChapterChapter 7
The endThe end