Phs 08 09
-
Upload
c2cha -
Category
Technology
-
view
2.627 -
download
0
Transcript of Phs 08 09
![Page 1: Phs 08 09](https://reader036.fdocuments.in/reader036/viewer/2022062513/554e7efeb4c90545698b51fa/html5/thumbnails/1.jpg)
PHOTOSYNTHESIS
Light Energy to Chemical Energy
![Page 2: Phs 08 09](https://reader036.fdocuments.in/reader036/viewer/2022062513/554e7efeb4c90545698b51fa/html5/thumbnails/2.jpg)
![Page 3: Phs 08 09](https://reader036.fdocuments.in/reader036/viewer/2022062513/554e7efeb4c90545698b51fa/html5/thumbnails/3.jpg)
Importance of Photosynthesis
• Source of atmospheric oxygen– Earth’s atmosphere
• 78% N2, 21% O2, 0.035% CO2
• Source of energy for food chain– Photoautotrophs vs. Heterotrophs
• Direct/indirect involvement in all products• Maintain stable ecosystem
![Page 4: Phs 08 09](https://reader036.fdocuments.in/reader036/viewer/2022062513/554e7efeb4c90545698b51fa/html5/thumbnails/4.jpg)
Photosynthesis and TranspirationWhole Plant Perspective
• CO2 enters leaf through open stomata; water is lost
• CO2 is converted to carbohydrate in the leaf & transported as sucrose in phloem
• Water is taken up by roots & transported via xylem
• Loss of water from the leaf via stomata is evapotranspiration
![Page 5: Phs 08 09](https://reader036.fdocuments.in/reader036/viewer/2022062513/554e7efeb4c90545698b51fa/html5/thumbnails/5.jpg)
Photosynthesis
6 H20 + 6 CO2 + Light Energy C6H12O6 + 6 O2
![Page 6: Phs 08 09](https://reader036.fdocuments.in/reader036/viewer/2022062513/554e7efeb4c90545698b51fa/html5/thumbnails/6.jpg)
![Page 7: Phs 08 09](https://reader036.fdocuments.in/reader036/viewer/2022062513/554e7efeb4c90545698b51fa/html5/thumbnails/7.jpg)
Chloroplast
GranumThylakoid
Stroma
Outer Membrane
Inner Membrane
![Page 8: Phs 08 09](https://reader036.fdocuments.in/reader036/viewer/2022062513/554e7efeb4c90545698b51fa/html5/thumbnails/8.jpg)
Thylakoid
Thylakoid Membrane
Thylakoid SpaceGranum
![Page 9: Phs 08 09](https://reader036.fdocuments.in/reader036/viewer/2022062513/554e7efeb4c90545698b51fa/html5/thumbnails/9.jpg)
Grana – Site of ‘Light Reactions’. Pigments Embedded in Thylakoid Membranes.
Stroma – Site of ‘Light-Independent Reactions’. CO2 Fixed into Sugar (Glucose). Membrane – Bounded by
2 smooth membranes
![Page 10: Phs 08 09](https://reader036.fdocuments.in/reader036/viewer/2022062513/554e7efeb4c90545698b51fa/html5/thumbnails/10.jpg)
Visible light
![Page 11: Phs 08 09](https://reader036.fdocuments.in/reader036/viewer/2022062513/554e7efeb4c90545698b51fa/html5/thumbnails/11.jpg)
Chlorophyll pigments harvest energy (photons) by absorbing certain wavelengths– Blue (420 nm)– Red (660 nm)
![Page 12: Phs 08 09](https://reader036.fdocuments.in/reader036/viewer/2022062513/554e7efeb4c90545698b51fa/html5/thumbnails/12.jpg)
Plants are green because the green wavelength is reflected, not absorbed.
![Page 13: Phs 08 09](https://reader036.fdocuments.in/reader036/viewer/2022062513/554e7efeb4c90545698b51fa/html5/thumbnails/13.jpg)
Photosynthetic Pigments
• Main photosynthetic pigment– Chlorophyll a
• Accessory Pigments– Absorb light & transfer energy to Chl a– Chlorophyll b– Carotenoids (Aids in photoprotection)
• Carotenes• Xanthophylls
![Page 14: Phs 08 09](https://reader036.fdocuments.in/reader036/viewer/2022062513/554e7efeb4c90545698b51fa/html5/thumbnails/14.jpg)
Photosynthetic Unit
• Chlorophyll bound to proteins in PS
• Light harvesting molecules pass their energy at a reaction center
• Two photosystems– PS I (P700)– PS II (P680)
![Page 15: Phs 08 09](https://reader036.fdocuments.in/reader036/viewer/2022062513/554e7efeb4c90545698b51fa/html5/thumbnails/15.jpg)
![Page 16: Phs 08 09](https://reader036.fdocuments.in/reader036/viewer/2022062513/554e7efeb4c90545698b51fa/html5/thumbnails/16.jpg)
Processes in Photosynthesis
(1) light O2 CO2
sugar
starchH2O
(2) Light Reactions (3) Dark Reactions
NADPH
ATP
![Page 17: Phs 08 09](https://reader036.fdocuments.in/reader036/viewer/2022062513/554e7efeb4c90545698b51fa/html5/thumbnails/17.jpg)
3 Processes in Photosynthesis
• Absorption of light energy– Pigments in thylakoids
• Light Reactions– Pigments & proteins in thylakoids– Generates ATP and NADPH
• “Dark” Reactions– Enzymes in stroma
– Reduce CO2 to carbohydrates using ATP & NADPH
![Page 18: Phs 08 09](https://reader036.fdocuments.in/reader036/viewer/2022062513/554e7efeb4c90545698b51fa/html5/thumbnails/18.jpg)
The light-dependent reactions of photosynthesis produce chemical energy in the form of ATP and NADPH.
![Page 19: Phs 08 09](https://reader036.fdocuments.in/reader036/viewer/2022062513/554e7efeb4c90545698b51fa/html5/thumbnails/19.jpg)
Lab 4B
• Expose samples to red wavelength– Why?
• Role of DPIP– Electron acceptor
• Works in place of NADP+– When DPIP is reduced, resultant increases
light transmittance
![Page 20: Phs 08 09](https://reader036.fdocuments.in/reader036/viewer/2022062513/554e7efeb4c90545698b51fa/html5/thumbnails/20.jpg)
Light Reaction
• Light Dependent Reaction• Captures Light Energy
– Electrons exited to higher energy state • Produces energy from solar power (photons) in the
form of ATP and NADPH
• Splits H2O, Uses H+ & Electrons, Spits out O2 as waste
• Two possible routes for electron flow:– Noncyclic Electron Flow– Cyclic Electron Flow
![Page 21: Phs 08 09](https://reader036.fdocuments.in/reader036/viewer/2022062513/554e7efeb4c90545698b51fa/html5/thumbnails/21.jpg)
Light ReactionNoncyclic Electron Flow
• Uses Photosystem II and Photosystem I• Uses Electron Transport Chain (ETC)
– Pq (Plastoquinone)– Cytochrome complex– Pc (Plastocyanin – Cu-containing proteins)
• Other proteins involved (P700)– Fd (Ferredoxin – Fe-containing protein)– NADP+ reductase
• Generates O2, ATP, and NADPH
![Page 22: Phs 08 09](https://reader036.fdocuments.in/reader036/viewer/2022062513/554e7efeb4c90545698b51fa/html5/thumbnails/22.jpg)
![Page 23: Phs 08 09](https://reader036.fdocuments.in/reader036/viewer/2022062513/554e7efeb4c90545698b51fa/html5/thumbnails/23.jpg)
![Page 24: Phs 08 09](https://reader036.fdocuments.in/reader036/viewer/2022062513/554e7efeb4c90545698b51fa/html5/thumbnails/24.jpg)
![Page 25: Phs 08 09](https://reader036.fdocuments.in/reader036/viewer/2022062513/554e7efeb4c90545698b51fa/html5/thumbnails/25.jpg)
Light ReactionCyclic Electron Flow
• Uses Photosystem I only• Uses Electron Transport Chain (ETC)
– Fd (Ferredoxin)– Cytochrome complex
• Generates ATP only– No production of NADPH
– No release of O2
![Page 26: Phs 08 09](https://reader036.fdocuments.in/reader036/viewer/2022062513/554e7efeb4c90545698b51fa/html5/thumbnails/26.jpg)
Cyclic Electron Flow
![Page 27: Phs 08 09](https://reader036.fdocuments.in/reader036/viewer/2022062513/554e7efeb4c90545698b51fa/html5/thumbnails/27.jpg)
Why Cyclic Electron Flow?
• Calvin cycle consumes more ATP than NADPH
• Makes up the difference needed for the Calvin cycle to function properly
![Page 28: Phs 08 09](https://reader036.fdocuments.in/reader036/viewer/2022062513/554e7efeb4c90545698b51fa/html5/thumbnails/28.jpg)
Light Reactions
Inputs Outputs
Light
H2O
ADP
NADP+
O2 (Waste)
ATP
NADPH + H+
Energy Carrier Molecules Take Converted ‘Light’
Energy to Stroma
![Page 29: Phs 08 09](https://reader036.fdocuments.in/reader036/viewer/2022062513/554e7efeb4c90545698b51fa/html5/thumbnails/29.jpg)
Chemiosmosis
• Powers ATP synthesis• Located in the thylakoid membranes• Uses ETC and ATP synthase (enzyme) to
make ATP• Photophosphorylation
– Addition of phosphate to ADP to make ATP
![Page 30: Phs 08 09](https://reader036.fdocuments.in/reader036/viewer/2022062513/554e7efeb4c90545698b51fa/html5/thumbnails/30.jpg)
![Page 31: Phs 08 09](https://reader036.fdocuments.in/reader036/viewer/2022062513/554e7efeb4c90545698b51fa/html5/thumbnails/31.jpg)
![Page 32: Phs 08 09](https://reader036.fdocuments.in/reader036/viewer/2022062513/554e7efeb4c90545698b51fa/html5/thumbnails/32.jpg)
![Page 33: Phs 08 09](https://reader036.fdocuments.in/reader036/viewer/2022062513/554e7efeb4c90545698b51fa/html5/thumbnails/33.jpg)
![Page 34: Phs 08 09](https://reader036.fdocuments.in/reader036/viewer/2022062513/554e7efeb4c90545698b51fa/html5/thumbnails/34.jpg)
Dark Reaction
• Light Independent Reaction, Calvin Cycle, Carbon Fixation
• Occurs in the stroma • Uses energy (ATP and NADPH) from light reaction
to make sugar (glucose) from CO2
• Uses CO2 • Regenerates ‘Empty’ Carrier Molecules (NADP+ &
ADP) • To produce glucose
– It takes 6 turns and uses 18 ATP and 12 NADPH
![Page 35: Phs 08 09](https://reader036.fdocuments.in/reader036/viewer/2022062513/554e7efeb4c90545698b51fa/html5/thumbnails/35.jpg)
3 Phases – Calvin Cycle
• Carbon fixation
• Reduction• G3P routes
![Page 36: Phs 08 09](https://reader036.fdocuments.in/reader036/viewer/2022062513/554e7efeb4c90545698b51fa/html5/thumbnails/36.jpg)
![Page 37: Phs 08 09](https://reader036.fdocuments.in/reader036/viewer/2022062513/554e7efeb4c90545698b51fa/html5/thumbnails/37.jpg)
PhotosynthesisPhotosynthesis
HH22OO COCO22
OO22 CC66HH1212OO66
Light Light ReactionReaction
Dark ReactionDark Reaction
Light is AdsorbedLight is AdsorbedBy By
ChlorophyllChlorophyll
Which splitsWhich splitswaterwater
ChloroplastChloroplast
ATP andATP andNADPHNADPH22
ADPADPNADPNADP
Calvin CycleCalvin Cycle
EnergyEnergy
Used Energy and is Used Energy and is recycled.recycled.
++
++
![Page 38: Phs 08 09](https://reader036.fdocuments.in/reader036/viewer/2022062513/554e7efeb4c90545698b51fa/html5/thumbnails/38.jpg)
Types of plantsProcesses of Photosynthesis
• C3 plants• C4 plants• CAM plants
![Page 39: Phs 08 09](https://reader036.fdocuments.in/reader036/viewer/2022062513/554e7efeb4c90545698b51fa/html5/thumbnails/39.jpg)
C3 photosynthesis
• Called ‘C3’ - 3-carbon acid (PGA)• Catalyzed by enzyme Rubisco
– Most abundant enzyme on Earth! • C3 pathway used by 85% of plants• Most trees and many crops use C3
photosynthesis
![Page 40: Phs 08 09](https://reader036.fdocuments.in/reader036/viewer/2022062513/554e7efeb4c90545698b51fa/html5/thumbnails/40.jpg)
Relatively high water loss
![Page 41: Phs 08 09](https://reader036.fdocuments.in/reader036/viewer/2022062513/554e7efeb4c90545698b51fa/html5/thumbnails/41.jpg)
Photorespiration
• Occurs on hot, dry, bright days• Stomata close• Fixation of O2 instead of CO2
• Produces 2-C molecules instead of 3-C sugar molecules
• Produces no sugar molecules or no ATP• Plants have special adaptations to limit the
effect of photorespiration.– C4 plants & CAM plants
![Page 42: Phs 08 09](https://reader036.fdocuments.in/reader036/viewer/2022062513/554e7efeb4c90545698b51fa/html5/thumbnails/42.jpg)
C4 Plants
• Hot, moist environments• 15% of plants (grasses, corn, sugarcane)• Divides photosynthesis spatially• Light rxn - mesophyll cells• Calvin cycle - bundle sheath cells
![Page 43: Phs 08 09](https://reader036.fdocuments.in/reader036/viewer/2022062513/554e7efeb4c90545698b51fa/html5/thumbnails/43.jpg)
C4 photosynthesis
• Four carbon molecule as 1st intermediate• Catalyzed by phosphoenolpyruvate
carboxylase (PEP carboxylase)• PEP carboxylase reacts effectively with CO2
at low concentrations• C4 plants can achieve high photosynthesis
with small stomatal opening, thereby saving water
• Carbon Fixation & Calvin cycle occur in two types of cells
![Page 44: Phs 08 09](https://reader036.fdocuments.in/reader036/viewer/2022062513/554e7efeb4c90545698b51fa/html5/thumbnails/44.jpg)
![Page 45: Phs 08 09](https://reader036.fdocuments.in/reader036/viewer/2022062513/554e7efeb4c90545698b51fa/html5/thumbnails/45.jpg)
CAM Plants
• Crassulacean Acid Metabolism • Hot, dry environments• 5% of plants (cactus and ice plants)• Stomates closed during day• Stomates open during the night
– Lower temperatures at night reduce water loss• Light rxn - occurs during the day• Calvin Cycle - occurs when CO2 is present• Carbon Fixation and Calvin cycle occur in the
same cell but at different times
![Page 46: Phs 08 09](https://reader036.fdocuments.in/reader036/viewer/2022062513/554e7efeb4c90545698b51fa/html5/thumbnails/46.jpg)