intro to biology week 7 of notes
intro to biology week 7 of notes BIOL-L 105
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This 25 page Class Notes was uploaded by Katelyn Scott on Friday September 11, 2015. The Class Notes belongs to BIOL-L 105 at Indiana University taught by T.J. Sullivan in Summer 2015. Since its upload, it has received 27 views. For similar materials see Introduction to Biology in Biology at Indiana University.
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Date Created: 09/11/15
Ch 10 Photosynthesis 10814 10814 3 Why photosynthesis matters lAll of the energy we need to live comes from photosynthesis 10814 ED Ways to get energy lAutotrophs III Make organic molecules from inorganic sources El Mostly plants photoautotrophs I Heterotrophs I Get energy from organic molecules in their environment El Bacteria fungi animals 10814 1 Why photosynthesis matters IA lot of the energy we use comes from photosynthesis 1 Wood III Ethanol El Biodiesel 11 Oil 8 coal 10814 Why photosynthesis matters I Raw materials Wood Paper Cotton I Environmental effects 10814 10814 Why study photosynthesis IAgriculture l2 of the energy that reaches a field is captured I Energy production Light energy to chemical energy I Electronics Molecular switches 10814 Why study photosynthesis I Environment COZ concentrations in the atmosphere effects on growth I Medicine Chlorophylllike molecules respond to light trigger reaction to destroy tumors Chlorophyll as a tumor preventer 10814 Van Helmont mid1600s IWhere do plants get their raw materials to grow Where does the mass come from IHypothesis The mass comes from materials taken up from the soil 10814 10814 q 5 years later 10814 Van Helmont mid16005 lWillow gained 165 lbs I Soil lost 2 oz lHe concluded the mass must come from the H20 10814 4T H1stor1ca1 expenments lPriestly 1771 1 Q How do plants breathe 1 H Plants give off 02 10814 Wait a few days 10814 10814 6 Wait a few days II 10814 Wait a few days 10814 Wait a few days 10814 Historical experiments IBy the mid18005 we know that plants required light C03 and H20 and O2 is produced I Photosynthesis proposed 6 CO2 12 H20 energy a CGHIZO6 6 02 6 H20 17 10814 Photosynthesis CO2 H20 energy a CSHIZO6 02 H20 lHow do the CO2 and H20 interact lAre you adding C to H20 or adding H to C02 10814 10814 Photosynthesis 19 10814 Purple sulfur bacteria I Can grow on food sources without sugar I Autotrophs I Need light and C02 but don t produce 02 10814 Purple sulfur bacteria coz 2 st light CHZOn H20 2 s 21 10814 Iquot Photosynthesis co2 HZS light gt CHZOn s H20 co2 H20 light gt CHZOn 02 H20 IWhen plants photosynthesize where does the 02 come from Where does the O for the H20 come from 10814 10814 Iquot Photosynthesis 6 co2 12 H20 energy a celeo6 6 02 6 H20 IO2 does not come from the C02 must come from H20 IWater and CO2 do not interact directly Photosynthesis is 2 separate reactions 23 10814 I Photosynthesis Light H20 capturing reactions 02 ATP NADPH Chemical energy I 2 reactions in photosynthesis I Lightcapturing reactions 39HZO is used I Calvin cycle 39C02 is used 602 Calvin cycle Chemical energy 10814 1 Rubisco 10814 10814 Fl Rubisco I I Catalyzes the reaction attaching CO2 to RuBP I Likely the most abundant protein on Earth I Cube shaped with g active sites 10814 fl L Rubisco I But I Rubisco is very slow 3 reactions sec I Will also attach O2 to RuBP Photorespiration 10814 27 Photorespiration Reaction with carbon dioxide during photosynthesis RuBP cog used in Calvin cycle two 3phosphoglycerate Reaction with oxygen during photonsplratlon RuBP 02 1 used in Calvin cycle one 3phosphogiycerate one 2phosphoglycolate V when processed 02 is released and ATP is used 10814 Fl I I Overall efficiency of photosynthesis drops dramatically I Need to keep CO2 concentrations high in the leaf to prevent this I This isn t always easy U Photorespiration Reaction with carbon dioxide during photosynthesis RuBP CO two 3phosphoglycerate used in Calvin cycle Reaction with oxygen during photonsplratlon RuBP quotl v when processed 002 is released and ATP is used used in Calvin cycle 10814 10814 31 4 Leaf morphology b Carbon dioxide diffuses into leaves through stomata l 1 quot I d 39 Photosynthetic Extracellular 602 Stoma cells space 10814 4 33 Leaf morphology b Carbon dioxide diffuses into leaves through stomata I As C02 and 02 are quot exchanged H20 is t 1 also exchanged quot l 55 V39Dsda i l Leaf surface H h x 139 l g Photosynthetic Extracellular 02 ce s 10814 4 Classic plant question 32 Leaf morphology a Leaf surfaces contain stomata 1 Q 39 1 Leaf surface mu th Guard cells 4 Pore scama 34 lWill you see this on the next lecture exam lWill you see this on the next lab exam 10814 i Photosynthesis occurs in the chloroplasts In plants cells that photosynthesi typically have 40 50 chloroplasts If i v v r 39 Af r 39 I Triplemembraned organelles I Form disklike structures called thylakoids Chloroplast Outer membrane Inner membrane I Stack of thylakoids grana 10814 10814 37 Photosynthesis occurs in the chloroplasts I Triplemembraned organelles I Form disklike structures called thylakoids I Stack of thylakoids grana lids flattened sacs 39 stack ol thylakoids liquid matrix 10814 38 Light energy Wavelengths um 105 103 10 10 103 105 107 109 1o 10 3 Gamma xra Ultra 39n amd Micro Radio rays Vs violet i waves waves Shorter I Longer wavelength wavelength Visible light 400 500 600 710 nm Higher A Lower energy 39 energy 10814 39 Capturing light ILight energy is captured by pigments I Mostly chlorophylls absorbs violet blue and red wavelengths I But also carotenoids absorb violet blue and green IWhich are the important wavelengths for photosynthesis 10814 10814 41 Capturmg 11ght Captur1ng11ght 10814 10814 43 Capturmg 11ght Captur1ng11ght quot a Different pigments absorb different wavelengths of 9 8 4 I I light E 7 393 A e Chlotophyll b e Chlorophylls absorb blue and red 5 6 4 8 cm h l light and transmit green light 2 5 q 398 mp w carom Carotonoids absorb blue 2 u and green light and a 4 A 395 transmit yellow orange 3 39 or red light 0 va 6 3 o 2 2 g g o as i 5 350 400 450 500 550 600 650 700 750 400 500 eoo 700 Wavelength nm V 39 I M Wavelength of light nm 10814 10814 10 10814 Fl 3 Ll Pigments b Chlorophylls a and b Ring rucmm I adquot n he cooquot absorbs Ham 0 l l I l Tall Hzc n c quot c c c O C a1quotr quot r39 quot auction chlorophyll in quot quot quot1 nu lhylakoid membrane 4W 39 u Fl 3 U Pigments a Bcarotene D mquot Pumn39 l oxmm Irr 10814 CH Ll When photons h1t electrons they gain energy e A quotquotquotquot Blue photons excite electrons to an even higher energy state 9 quotquotquot Red photons excite electrons to a highenergy state 13339 l 0 1 2 Energy state of electrons In chlorophle 10814 CH 47 When photons hit electrons they gain energy rwonsscaacs m 090 back down to Iowa envoy Incl Ma and on Higher ovumd I If the energy isn t used it is released as m light and or heat 3 6 Wm M I Fluorescence E 5 Low CNoroohyI molecule 11 Light reactions ILight is captured by by an antenna like structure Photosystem Energy captured by l chlorophyll is transferred to neighboring chlorophylls until it reaches the reaction center I Resonance 10814 10814 Resonance FLUORESCENCE or RESONANCE 39 M e or REDUCTIONOXIDATIOI um I r n 0 39939 0quot WI MK I 0039 Comm m We Higher sml d w v i mu Enovgy of ouclmo i S l LOW ROUNDquot OOH 10814 Reaction center REDUCTIONOXIDATION Electron it random to o m compound I Energy is used to transfer an electron to a new molecule I Change in energy s form a Light to chemical Kinetic to potential auction MO 10814 How is the energy transferred IThe behavior of high energy electrons wasn t understood until the 50 s IIn algae photosynthesis is stimulated by both red 680 nm and far red 700 nm wavelengths I How would using both wavelengths affect photosynthesis 10814 12 How is the energy transferred EXPERIMENT EXPERIMENTAL SETUP Farred light Red light Both 700 nm 680 nm wavelengths 4 1 7 7 r t i Expose cells to light and record rate at photosynthesis PREDICTION When the two wavelengths are combined the rate at photosynthesis will double PREDICTION OF NULL HVPOTHESIS When the two the rate on n uu the same as for each wavelength alone 10814 How is the energy transferred EXPERIMENT RESULTS Both A wavelengths w E W quota o a 39U 0 I n s Farred light Red light a 700 nm 680 nm 5 W AM Time CONCLUSION Neithei hypothesis is correct The combination of both wavelengths more than doubles the rate at photosynthesis A new hypothesis is required to explain this enhancement etlecL u n 10814 Light reactions II l 3 ICombining the 2 wavelengths more than doubled the rate of photosynthesis Enhancement effect Photosystems I 2 types of photosystem Photosystem l and photosystem 2 I Names were given in the order they were discovered Photosystem 2 comes first 10814 13 10814 q 57 Photosystem 2 Photosystem 2 Embedded in the thylakoid membrane 7 V clwclcr r V clwclcr Thts box endows om This box encloses om wolosyslem II complex that photosyslem II complex that coma ns 19 pcolmn subunits coma ns 19 pcolmn subunits Clwmd39qIAlervl39y wvxr WM I Bh llih b t l CINMM39QH F39VVI15 39m WM I en llihnb l A quotII kl h quotQtI39M our m39q Iquot 24quot X 5 MR W Itquotan A quotII kl h quotQtIN vylwp m q Iquot 24quot X 5 M W Itquotan 10814 10814 More up tO date Overall structure of PSII dimer from 39139 vulcanus at a resolution of 19 A i 3 Y Umena et al 201 1 Crystal structure of oxygenevolving photosystem II at a resolution of 19 A Nature 4735560 IA 1x 103910 meters 1 mm 10000000 A Y Umena et al Nature 000 16 2011 doi101038nature09913 tLII39C 10814 14 Hydrogen bond network around Yz b v A K 0 u 3 010319 imazz x i 9 a lt YE Y 7 0 9 H6 s 3 0 CNSMl 0 0 Q1416 Y Umena et al Nature 000 16 2011 doi101038nature0001 4 nature 10814 Photosystem 2 IChlorophyll captures solar energy with an electron IEnergy is transferred from the reaction center to pheophytin Takes about 23 x 103912 00000000000025 seconds IThe electron then enters an electron transport chain 10814 I H U Photosystem 2 Photon Phclocyllnm II 10814 63 1quot Photosystem 2 IThe electron transport chain pumps protons into the thylakoid Concentration of H is 1000 higher on the inside IConcentration gradient is used to power ATP production 10814 15 Photosystem 2 I Overall An electron moved from the reaction center to the cytochrome complex Energy was used to create a H gradient IWhere can the reaction center replace that electron 10814 10814 Photosystem 2 2H20 gt4H4e3902 I Photosystem 2 can split water harvest the electrons lThis is why plants give off 02 during photosynthesis IPhotosystem 2 is the only protein complex that can do this 10814 Photosystem 2 2H20 gt4H4e3902 IPhotosystem 2 is the only protein complex that can do this I Requires energy but not from ATP energy from sunlight 10814 Photosystem 2 Oxygen Content of Earth39s Atmosphere Dunng the C0068 0 the Lab Bdllon Yeats 1000 900 600 70 00 5ch 4wa JOE 230 100 0 MIIIIOnS 039 Years Below Present 10814 16 10814 Photosystem 1 I Antenna complex captures energy from 2 photons sends it to reaction center Energy at electron 2e39 2 Photons 51a 0quot I VII s50 hai NADP39 H ADP 39 Formdoxin V N reductase NADPH 10814 Photosystem 1 El Bobbn 2e 39a spo 1 chain 39 Formdoxin V NADP H NADP reductase I Energy excites 2 e39 they escape NADPH 2 Photons I Move to membrane bound proteins that contain iron Energy at electron 10814 Photosystem 1 I 2 e39 and l proton are used to convert NADP to NADPH Energy at electron 2e39 s50 hai NADP39 H ADP 2 Photons 51a 0quot I VII 39 Formdoxin V N reductase NADPH 70 10814 71 Interactions between photosystems IRemember the experiment showing that 680 nm light and 700 nm light more than doubled photosynthesis when used together 10814 17 10814 I H U Z scheme model i Snowy a doelm I Describes the energy changes during photosynthesis 10814 H I U Z scheme model i Emmy a electron I Noncyclic e39 ow take from H20 put into NADPH ATP I produced no pvolonmom Force 10814 I H U Z scheme model i Emy nl doclm I Electron is energized twice first at P32 then at P31 10814 H I U Z scheme model i Emmy cl 000qu I PSZ works best with 680 nm light PSl works best with 700 nm light 10814 18 10814 EXPERIMENT 7 1 nesuus Both Cyclic photophosphorylation A wavelengths w E 4w 339 0 3 390 O a 5 Farred light Red light I e39 can leave PSI and 9 2 quot00 quotml 680 quotml reenter the electron c x W m g o i transport chain g T I Sacr1f1ces NADPH to 5 7 quotquote i 77 make additional ATP CONCLUSION Neither hypothesis is correct The combination of both wavelengths more than doubles the rate of photosynthesis A new hypothesis is required to explain this enhancement effect J ItKll whvlx1tsv N 10814 10814 78 79 Light reactions Calvin cycle IElectrons are taken from H20 ICharged using light energy at P32 Energy used to make proton gradient I Energy generated 1n the 11ght react10ns IS used to fix carbon Proton gradient used to make ATP Fix convert CO2 to a usable organic form IElectrons recharge at PS Electrons incorporated into NADPH IStudy pretems usmg radlatlonm or sometimes back to the electron transport chain 10814 10814 19 EXPERIMENT EXPERIMENTAL SETUP 146 l1 co2 2 1 3 1 Feed algae pulse r u of labeled 002 i if O 2 Homogenize cells Pulsechase experiment 3 Separate molecules 1 Use radioactively labeled COZ to identify the molecules between CO2 and glucose 4 Locate label PREDICTION No speci c prediction 1 he mm H 10814 10814 Calvin cycle EXPERIMENT RESULTS l 3Phosphoglycerate 5 3 Compounds produced Compounds produced after 5 seconds after 60 seconds CONCLUSION 3Phosphoglycerate is the rst intermediate product Other intermediates appear later t minumimAmm u Same 3PG that we saw in cellular respiration E 10814 Real data resides in the number position and intensity that is radioactivity of the blackened areas The paper ordinarily does not print out the names of these compounds unfortunately and our principal chore for the succeeding ten years was to properly label those blacked areas on the film Melvin Calvin 1961 10814 Calvin cycle lLike the citric acid cycle starting molecules are generated in the last step I 3 phases C02 fixation COZ captured in organic molecule C02 reduction Energy added requires ATP NADPH Regeneration of RuBP 10814 20 H I U Calvin cycle All Huron phases 0 he Cillvn cycle lnkn plum In i oh39 3 RuBP 3 C02 gt 6 3phosphoglycerats 25 8 3mosphoglycorate o 8 ATP 4 6 quotADPquot 3 Bow quotmaubi ices 3ATP gt 3RuaP Hm strumquot ul hlompllwhz a The Calvin cycle has three phases 5 63 to step 3 1 03 yield to glucosefructose 10814 H I U Calvin cycle I CO2 reduction ATP is used to reduce 3PG to BPG 10814 10814 H I U Calvin cycle I Fixation 3 CO2 molecules attached to 3 RuBP Quickly rearranges to 3PG C 87 Calvin cycle I CO2 reduction NADPH reduces BPG we to GSP l G3P molecule leaves the cycle a 21 Calvin cycle I Regeneration of RuBP 3 ATPs are used to covert 5 GSP molecules to 3 RuBP moleucles I GSP 3 carbons I RuBP 5 carbons 88 10814 10814 Calvin cycle overview I 3 C02 are captured with 3 RuBP I Energy from the light reactions ATP NADH is used to reduce these molecules I l 3carbon molecule is spun out of the cycle I Remaining molecules are restructured into 3 molecules of RuBP 10814 Fate of the GSP Glucolcv 2 cap lmclosa lt A Roachons In chloroplast sulfa Glucose Glucose Glucose CNJON cupu cupn 510mg ljn HAIL IllillliZZU oquot 0 390 0 h r llu 39n 1 ON ON W 10814 How is photosynthesis regulated ILight increases production of proteins needed for photosynthesis I High sugar concentrations inhibits production of proteins needed for photosynthesis I Low Pi levels increases Calvin cycle rate 10814 22 l39l Low Pi levels Hun 10814 Leaf morphology I Close stomata to conserve water I but then C02 concentration drops while 02 concentration rises I Photorespiration b Carbon dioxide diffuses into leaves through stomata r 39 Photosynthetic Extracellular 02 ce s 10814 C3 photosynthesis I What controls the rate of CO2 and H20 movement I 111 mm mm plant a rMylll r hl IIku 39r in thc memle cells During C mymxo v i m I M RIB In I m PGA In aganic Kid minigihmcmm l Magnituch an may 7 quot quot 39 Itolmlcnw ich maybe The nal puncu lminea m m such 10814 10814 H I U Photorespiration 97 Hot dry air gt evaporation via stomata gt closing of stomata gt reduced CO2 in the leaf gt photorespiration gt less energy from photosynthesis How can plants avoid photorespiration 10814 23 10814 Adaptations to increase C02 in Adaptations to increase C02 in leaves leaves I Hide the Calvin cycle I C4 plants b I Cycle occurs in cola1 bundlesheath cells a c4 plant WSW Mastoghngeus I C02 is captured in a Mamquot no contact With the carboxv39ase 4 carbon molecule 5 6 Bundlesheath cells PEP cycle contain rubisco 4 C 1 Vasculartlssue I I 7 1 co l Rimes316am I r I be r 4 p ants sheath cell mi V plants that use quot 13313 7 L vanilla I C02 is released used T 3 quot Sugarvzsscsuir photosynthesis are in Calvin cycle C3 plants 10814 10814 c3 vs C4 c3 vs C4 39 l I Hot dry habitats I nght reaCtlonS I Light reactionsCalvin C Plant 7m ophyll 1 m 39 39 ca CYC e sa e cycle In different cells 4 cell SM I Capturing C02 costs 35132523135213 I No energy required energy 92 if 13 to get C02 I More ef cient at low v 39 mam 39 ES 7 39quot n n r 39 n 5 39 c I More eff1c1ent at high C02 C0 ce t atlo s COZ concentrations I 3 of plants corn sugar cane 10814 10814 24 10814 CH C 103 Adaptations to increase C02 in Adaptations to increase C02 in leaves leaves COQiS stored amigm and used during the day I plants COQis stored amigm and used during the day I Separate by time of 39 BeSt in VerY hOta drY Gap day habitats W I Onl r open stomata at 39 caCti pineapple night 25
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