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Do-NowGroup Discussion
• In your groups, discuss the 2014 FRQ prompt • Discuss possible answers for each part
• Jot down your ideas as a group to help plan a response
• Revise your explanations until you have the BEST possible answer
Announcements• Clearmissingassignments!
• StudyforCh.10quiz&Ch.9-10testJ• Quarter1ends10/14à
• Retakes/missingworkbyTuesday
CW/HW Assignments 7. Ch. 9 Practice FRQ 8. Ch. 10 Lecture Notes 9. Ch. 10 VCN
1. Labs and logs MUST be turned in 2. Ch. 10 Video CN (1 video) 3. Study Ch. 9-10 4. Lab next Friday
PLANNER
EssenJalknowledgestandards• 2.A.1: All living systems require constant input of free energy
• 2.A.2: Organisms capture and store free energy for use in biological processes
FLT• I will be able to:
• describe the structure of a chloroplast
• describe the the role of ATP and NADPH in the Calvin Cycle
• compare and contrast oxidative phosphorylation and photophosphorylation in chloroplasts
• By completing Ch. 10 Lecture Notes
Energy=Life• Alllivingorganismsmustobtainenergyinordertolive
• Autotrophs=Producetheirownenergyviaphotosynthesisorchemosynthesis
• Heterotrophs=consumeotherorganisms
Ø Theycapturefreeenergypresentincarboncompoundsproducedbyotherorganisms
Energy=Life• AutotrophsmaketheirownfoodandsustainthemselveswithouteaJnganythingderivedfromotherorganisms
• Autotrophsaretheproducersofthebiosphere,producingorganicmolecules(suchasglucose)fromCO2andotherinorganicmolecules
• Almostallplantsarephotoautotrophs,usingtheenergyofsunlighttomakeorganicmoleculesfromwaterandcarbondioxide
9
Autotrophs = Producers
(a) Plants
(c) Unicellular protist 10 µm
1.5 µm
40 µm (d) Cyanobacteria
(e) Purple sulfur bacteria
(b) Multicellular alga
Review• Livingcellsrequireenergyfromoutsidesources
• Energyflowsintoanecosystemassunlightandleavesasheat
• PhotosynthesisgeneratesO2andorganicCHOmolecules(usedincellularrespiraJon)
Energy Flow and Chemical Recycling in Ecosystems
IN: Light Energy
ECOSYSTEM
Photosynthesis in chloroplasts
CO2 + H2O
Cellular respiration in mitochondria
Organic Molecules + O2
ATP powers most cellular work
OUT: Heat energy
ATP
Chloroplasts• Photosynthesistypicallyoccursinleaves• Chlorophyll,apigmentfoundinchloroplasts,givesthemtheirgreenappearance
• ChlorophyllabsorbsvisiblelightE,whichisusedtosynthesizeorganicmoleculessuchasglucose
• CO2entersandO2exitstheleafthroughmicroscopicporescalledstomata
13
Zooming in on the location of photosynthesi
s in a plant
5 µm
Mesophyll cell
Stomata CO2 O2
Chloroplast
Mesophyll
Vein
Leaf cross section
Pair-Share-Respond1. Whatarephotoautotrophs?
2. Describethemainstructuresofthechloroplast
3. Whatisthesignificanceofastomata?
4. Whatarecyanobacteria?
RespiraJonReview• Recall:
• 6O2+C6H12O6à6CO2+6H2O+Energy
• Thisoccursinthreemainsteps:
• Glycolysis• Krebs/CACycle• ETC
• Wheredoestheglucosecomefrom??
24
PhotosynthesisOverview• Photosynthesis=energytransferprocessthatconvertssolarenergyintostoredchemicalenergy
• PhotosynthesisprovidestheEarthwithfoodandatmosphericoxygen
25
PhotosynthesisOverview• Photosynthesis can be summarized with the
following equation 6CO2 + 6H2O + Light E è C6H12O6 + 6O2
26
PhotosynthesisOverview• PhotosynthesisisaredoxreacJon:
• H2OisoxidizedtoO2
• CO2isreducedtoC6H12O6
28
Stages1. The light dependent reactions
• Occur within and across the thylakoid membrane
• H2O is split into hydrogen and oxygen (photolysis)
• The e-s hold the free energy from the light
• Through an ETC, light E is transformed into ATP and NADPH
• Generate ATP by photophosphorylation
30
Stages2. The light independent reactions (Calvin Cycle)
• Takes place in the stroma
• Forms C6H12O6 from CO2 using ATP and NADPH
• The Calvin Cycle begins with carbon fixation, which incorporates CO2 into organic molecules and then reduction produces sugar
32
Light
Photosynthesis H2O
Chloroplast
Light Reactions
NADP+
P ADP
i+
ATP
NADPH
O2
Calvin Cycle
CO2
[CH2O] (sugar)
Pair-Share-Respond1. Definephotosynthesis2. Whyisphotosynthesisconsideredto
bearedoxreacDon?Bespecific
3. Whatarethetwostagesofphotosynthesisandwheredotheytakeplace?
4. IdenDfytwothingsthatoccurinthefirststage.
TheNatureofSunlight• LightisaformofelectromagneJcenergy,alsocalled
electromagneJcradiaJon
• LikeotherelectromagneJcenergy,lighttravelsinrhythmicwaves
• Wavelengthisthedistancebetweencrestsofwaves
• WavelengthdeterminesthetypeofelectromagneJcenergy
39
TheNatureofSunlight• TheelectromagneDcspectrum=theenDrerangeof
electromagneDcenergy,orradiaDon
• Visiblelightconsistsofwavelengths(includingthosethatdrivephotosynthesis)thatproducecolorswecansee
• LightalsobehavesasthoughitconsistsofdiscreteenergyparJcles,calledphotons
40
UV
Visible light
Infrared Micro- waves
Radio waves X-rays Gamma
rays
103 m 1 m
(109 nm) 106 nm 103 nm 1 nm 10–3 nm 10–5 nm
380 450 500 550 600 650 700 750 nm
Longer wavelength Lower energy Higher energy
Shorter wavelength
Electromagnetic Spectrum
PhotosyntheJcPigments:LightReceptors• Pigments=substancesthatabsorbvisiblelight
• Differentpigmentsabsorbdifferentwavelengths
• WavelengthsthatarenotabsorbedarereflectedortransmiZed
• Leavesappeargreenbecausechlorophyllreflectsgreenlight.Weseereflectedlight.
42
Why leaves are green: interaction of light with chloroplasts
Reflected light
Absorbed light
Light
Chloroplast
Transmitted light
Granum
Spectrophotometer• Spectrophotometer=measuresapigment’sabilitytoabsorb
variouswavelengths
• ThismachinesendslightthroughpigmentsandmeasuresthefracJonoflighttransmiZedateachwavelength
• TransmiZedlightislightthatisnotabsorbed
45
Determining an absorption spectrum
Galvanometer
Slit moves to pass light of selected wavelength
White light
Green light
Blue light
The low transmittance (high absorption) reading indicates that chlorophyll absorbs most blue light.
The high transmittance (low absorption) reading indicates that chlorophyll absorbs very little green light.
Refracting prism
Photoelectric tube
Chlorophyll solution
TECHNIQUE
1 2 3
4
AbsorpJonSpectrum• Absorption spectrum = a graph plotting a
pigment’s light absorption vs. wavelength • Spectrum of chlorophyll a shows that violet-blue
and red light work best for photosynthesis
• An action spectrum profiles the relative effectiveness of different wavelengths of radiation in driving a process such as photosynthesis
47
Wavelength of light (nm)
Action spectrum
Absorption spectra
Engelmann�s experiment
Aerobic bacteria
RESULTS
Rat
e of
pho
tosy
nthe
sis
(mea
sure
d by
O2 r
elea
se)
Abs
orpt
ion
of li
ght b
y ch
loro
plas
t pig
men
ts
Filament of alga
Chloro- phyll a Chlorophyll b
Carotenoids
500 400 600 700
700 600 500 400
• ChlorophyllaisthemainphotosyntheDcpigment
• Itabsorbsthelightenergy• Accessorypigments,suchaschlorophyllb,broadenthe
spectrumusedforphotosynthesis
• Accessorypigmentscalledcarotenoidsabsorbexcessivelightthatwoulddamagechlorophyll
50
Chlorophyll
Porphyrin ring: light-absorbing �head� of molecule; note magnesium atom at center
in chlorophyll a CH3
Hydrocarbon tail: interacts with hydrophobic regions of proteins inside thylakoid membranes of chloroplasts; H atoms not shown
CHO in chlorophyll b
Chlorophyll• Energyfromphotonsmaybeabsorbedbyelectrons
• Whenapigmentabsorbslight,itgoesfromagroupstatetoanexcitedstate,whichisunstable
• Whenexcitede-sreturntothegroundstate,photonsaregivenoff,anaUerglowcalledfluorescence
• Ifilluminated,anisolatedsoluJonofchlorophyllwillfluoresce,givingofflightandheat
52
Chlorophyll
Porphyrin ring: light-absorbing �head� of molecule; note magnesium atom at center
in chlorophyll a CH3
Hydrocarbon tail: interacts with hydrophobic regions of proteins inside thylakoid membranes of chloroplasts; H atoms not shown
CHO in chlorophyll b
Excitation of isolated chlorophyll by light
(a) Excitation of isolated chlorophyll molecule
Heat
Excited state
(b) Fluorescence
Photon Ground state
Photon (fluorescence)
Ener
gy o
f ele
ctro
n
e–
Chlorophyll molecule
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