AP Biology. AP Biology Photosynthesis: Life from Light and Air

Transcription

1 Photosynthsis: Lif from Light and Air

2 Enrgy nds of lif All lif nds a constant input of nrgy Htrotrophs (Animals) consumrs producrs gt thir nrgy from ating othrs at food = othr organisms = organic molculs mak nrgy through rspiration Autotrophs (Plants) produc thir own nrgy (from slf ) convrt nrgy of sunlight build organic molculs (CHO) from CO 2 mak nrgy & synthsiz sugars through photosynthsis How ar thy connctd? Htrotrophs making nrgy & organic molculs from ingsting organic molculs glucos + oxygn carbon + watr + nrgy dioxid C 6 H 12 O 6 + 6O 2 6CO 2 + 6H 2 O + oxidation = xrgonic Autotrophs making nrgy & organic molculs from light nrgy carbon dioxid + watr + nrgy glucos + oxygn 6CO + 2 6H 2 O + light C 6 H 12 O 6 6O nrgy + 2 rduction = ndrgonic Whr s th? 2

3 What dos it man to b a plant Nd to collct light nrgy transform it into chmical nrgy stor light nrgy in a stabl form to b movd around glucos th plant or stord nd to gt building block atoms from th nvironmnt C,H,O,N,P,K,S,Mg produc all organic molculs ndd for growth CO 2 N K P carbohydrats, protins, lipids, nuclic acids H 2 O Plant structur Obtaining raw matrials sunlight lavs = solar collctors CO 2 stomats = gas xchang H 2 O uptak from roots nutrints N, P, K, S, Mg, F uptak from roots 3

4 stomat transpiration gas xchang lavs Chloroplasts cross sction of laf absorb sunlight & CO 2 CO 2 chloroplasts in plant cll chloroplast chloroplasts contain chlorophyll mak nrgy & sugar 4

5 Plant structur Chloroplasts doubl mmbran stroma fluid-filld intrior thylakoid sacs grana stacks Thylakoid mmbran contains chlorophyll molculs lctron transport chain synthas gradint built up within thylakoid sac chloroplast H+ H+ thylakoid H+ outr mmbran stroma thylakoid granum H+ innr mmbran Photosynthsis Light ractions light-dpndnt ractions nrgy convrsion ractions convrt solar nrgy to chmical nrgy & NADPH Calvin cycl light-indpndnt ractions sugar building ractions It s not th Dark Ractions! uss chmical nrgy ( & NADPH) to rduc CO 2 & synthsiz C 6 H 12 O 6 5

6 Light ractions Elctron Transport Chain lik in cllular rspiration protins in organll mmbran lctron accptors NADPH proton ( ) gradint across innr mmbran find th doubl mmbran! synthas nzym chloroplast H+ H+ + H+ H+ H+ + H+ thylakoid ETC of Rspiration Mitochondria transfr chmical nrgy from food molculs into chmical nrgy of us lctron carrir NADH gnrats H 2 O 6

7 Chloroplasts transform light nrgy into chmical nrgy of us lctron carrir NADPH gnrats O 2 Th that Jack built photosynthsis movs th lctrons runs th pump pumps th protons builds th gradint rspiration sunlight brakdown of C 6 H 12 O 6 drivs th flow of protons through synthas bonds P i to ADP ADP + P i gnrats th that volution built 7

8 Pigmnts of photosynthsis Chlorophylls & othr pigmnts mbddd in thylakoid mmbran arrangd in a photosystm collction of molculs structur-function rlationship How dos this molcular structur fit its function? A Look at Light Th spctrum of color V I B G Y O R 8

9 Light: absorption spctra Photosynthsis gts nrgy by absorbing wavlngths of light chlorophyll a absorbs bst in rd & blu wavlngths & last in grn accssory pigmnts with diffrnt structurs absorb light of diffrnt wavlngths chlorophyll b, carotnoids, xanthophylls Why ar plants grn? Photosystms of photosynthsis 2 photosystms in thylakoid mmbran collctions of chlorophyll molculs act as light-gathring molculs Photosystm II raction chlorophyll a cntr P 680 = absorbs 680nm wavlngth rd light Photosystm I chlorophyll b P 700 = absorbs 700nm wavlngth rd light antnna pigmnts 9

10 chlorophyll a Photosystm II chlorophyll b Photosystm I sun 1 Photosystm II P680 chlorophyll a 10

11 Inhal, baby! chloroplast H+ H+ + H+ thylakoid H+ H+ + H+ Plants SPLIT watr! 2 1 O H O H H H - - +H fill th vacancy Photosystm II P680 chlorophyll a chloroplast H+ H+ + H+ thylakoid H+ H+ + H H H+ + H+ to Calvin Cycl nrgy to build carbohydrats Photosystm II P680 chlorophyll a ADP + P i 11

12 sun 5 Photosystm II P680 chlorophyll a Photosystm I P700 chlorophyll b lctron carrir 6 5 sun Photosystm II P680 chlorophyll a Photosystm I P700 chlorophyll b $$ in th bank rducing powr! 12

13 sun sun split H 2 O O H + H + to Calvin Cycl ETC uss light nrgy to produc & NADPH go to Calvin cycl PS II absorbs light xcitd lctron passs from chlorophyll to primary lctron accptor nd to rplac lctron in chlorophyll nzym xtracts lctrons from H 2 O & supplis thm to chlorophyll splits H 2 O O combins with anothr O to form O 2 O 2 rlasd to atmosphr and w brath asir! 13

14 Exprimntal vidnc Whr did th O 2 com from? radioactiv tracr = O 18 Exprimnt 1 6CO + 2 6H 2 O + light C 6 H 12 O 6 6O nrgy + 2 Exprimnt 2 6CO + 2 6H 2 O + light C 6 H 12 O 6 6O nrgy + 2 Provd O 2 cam from H 2 O not CO 2 = plants split H 2 O! Noncyclic Photophosphorylation Light ractions lvat lctrons in 2 stps (PS II & PS I) PS II gnrats nrgy as PS I gnrats rducing powr as NADPH 14

15 Cyclic photophosphorylation If PS I can t pass lctron to NADP it cycls back to PS II & maks mor, but no NADPH coordinats light ractions to Calvin cycl Calvin cycl uss mor than NADPH NADPH 1 C 6 H 12 O 6 Photophosphorylation cyclic photophosphorylation NADP NONcyclic photophosphorylation 15

16 Photosynthsis summary Whr did th nrgy com from? Whr did th lctrons com from? Whr did th H 2 O com from? Whr did th O 2 com from? Whr did th O 2 go? Whr did th com from? Whr did th com from? What will th b usd for? Whr did th NADPH com from? What will th NADPH b usd for? stay tund for th Calvin cycl You can grow if you Ask Qustions!

17 Ghosts of Lcturs Past (storag) Stomats 17