photosynthesis autotrophic organisms photoautotrophs photoautotrophs chapter 14

Transcription

1 autotrophc organsms heterotroph autotrophs produce organc nutrents from and HS. Chemoautotrophs use energy from norganc. hotoautotrophs use radant energy to make organc compounds photosynthess chapter 4 photoautotrophs photoautotrophs photosynthess found n plants algae protsts some prokaryotes harvests energy from the sun carbohydrates photosynthess low energy electrons converted to hgh energy electrons used to chan carbon atoms together electron donors H S H cyanobactera

2 plant structure leaves photosynthetc organs eudcots two layers of mesophyll palsade spongy stomata chloroplasts plastds specal organelles found n plants nvolved n varous metabolc processes and storage develop from proplastds n merstem chloroplasts specalzed plastds nvolved n the process of photosynthess double outer nner Thylakod Stroma Granum Mesophyll Leaf cross secton s Stomata uter Inter Inner Mesophyll cell Ven 0 μm μm chloroplasts photosynthess outer nter nner stroma thylakod grana thylakod Stroma Granum Thylakod uter Inter Inner basc reacton aerobc respraton n reverse + H + energy C H + + H Reactants: roducts: C H H H becomes reduced μm Energy + + H C H + becomes oxdzed

3 photosynthess lght-dependent energy from sunlght absorbed stored as and lghtndependent converted to carbs uses energy from and H Reactons NAD + AD + [CH ] (sugar) harvestng lght wavelength shorter wavelength = hgher energy absorpton photon absorbed by molecule electron excted 0 5 nm 0 nm nm 0 nm 0 nm (09 nm) 0 m Gamma rays X-rays UV Infrared Mcro- waves Vsble lght Rado waves nm m Shorter wavelength Hgher energy Longer wavelength Lower energy harvestng lght chlorophyll structure porphyrn rng hydrocarbon tal hydrophobc carotenods accessory pgments absorb blue & green lght CH CH n chlorophyll a CH n chlorophyll b orphyrn rng Thylakod Chlorophyll STRMA hytol tal roten subunts THYLAKID SACE Structure of photosystem II

4 harvestng lght photosystems photosystems photosynthetc unt antenna reacton-center hoton - harvestng complexes hotosystem Reacton- center complex STRMA rmary electron photosystem II boosts electrons energy level to mdpont reacton center (80) photosystem I boosts electrons energy level above NAD + reacton center (700) Z scheme - rmary Thylakod Transfer of energy Specal par of chlorophyll a gment THYLAKID SACE (INTERIR F THYLAKID) 80 gment hotosystem II (S II) splttng water splttng water photosystem II lght-harvestng complex II contans most of the antenna pgments lght energy transmtted to core of S photosystem II transfers electron to pheophytn prmary electron pheo (powerful oxdzng agent) pheo- donates electron to plastoqunone wth next photon, plastoqunone reduced to plastoqunol (QH) photolyss requres 4 electrons ( for each atom)

5 producton of brdgng the gap QH -> cytochrome bf (multproten complex) electrons passed to plastocyann plastocyann passes electrons to Granum Thylakod producton of photosystem I LHC 700 transfers electron to A electron replaced by ncomng electron passed from lumen sde to stroma sde ferredoxns nteract wth ferredoxn NAD + reductase FAD group - accepts e - μm accountng of produced per released Mtochondron x H + + / H rmary q 4 Electron transport chan Cytochrome complex c rmary 700 Fd Electron transport chan 7 8 NAD + reductase NAD + + H + x MITCHNDRIN STRUCTURE Inter Inner Electron transport chan H+ Dffuson CHLRLAST STRUCTURE 80 5 Matrx synthase Stroma hotosystem II (S II) gment hotosystem I (S I) Key Hgher [H+ ] Lower [H+ ] AD + H+

6 powerng the C cycle STRMA (low H + concentraton) THYLAKID SACE (hgh H + concentraton) hotosystem II H / 4 H + + H + q Cytochrome complex 4 H + c hotosystem I Fd NAD + reductase NAD + + H + To photophosphorylaton producton of ph gradent establshed synthase pumps H + out of lumen noncyclc phosphoryaton cyclc phosphorylaton sometmes electrons from ferredoxn passed back to cytochrome complex pump H + nto lumen synthase AD STRMA (low H + concentraton) + H + Carbon fxaton C pathway / Calvn cycle three phases carbon fxaton reducton regeneraton of condensed wth RuB forms -carbon ntermedate Rbulose bsphosphate (RuB) splt nto -phosphoglycerate (GA) Input Rubsco (Enterng one at a tme) hase : Carbon fxaton Short-lved ntermedate -hosphoglycerate calvn cycle reducton GA reduced to GA used to make glucose, fructose, sucrose regeneraton of RuB Rbulose bsphosphate (RuB) AD hase : Regeneraton of the (RuB) 5 G Input Rubsco (Enterng one at a tme) hase : Carbon fxaton Short-lved ntermedate -hosphoglycerate,-bsphosphoglycerate AD NAD + Glyceraldehyde -phosphate hase : (G) Reducton G Glucose and (a sugar) other organc utput compounds

7 carbohydrate synthess GA exported nto cytoplasm exchanged for phosphate used to synthesze sucrose H can reman n chloroplast Reactons: hotosystem II Electron transport chan hotosystem I Electron transport chan NAD + AD + RuB -hosphoglycerate G Starch (storage) photorespraton when stomata are closed rubsco --> --> -carbon compound -phosphoglycolate consumes, releases - no sugars glycolate -> glycoxylate -> glycne ( released) perhaps evolutonary relc lmts buldup of damagng lght reacton products problem for plants when hot and dry Sucrose (export) C4 plants CAM plants adaptaton to hot clmate C4 pathway works well wth low combned wth E produce 4-carbon compounds passed to bundle sheath cell and calvn cycle manly found n monocots manly grasses corn, sorghum, sugar cane The C 4 pathway Mesophyll cell E carboxylase xaloacetate (4C) Bundle- sheath cell Malate (4C) E (C) AD mesophyll bundle yruvate sheath (C) cells Sugar Vascular tssue crassulacean acd metabolsm open stomata at nght fx close stomata durng day use from CAM pathway examples orchds, bromelads, pneapple ncorporated (carbon fxaton) released to the cycle CAM rganc acd Sugar Nght Day Temporal separaton of steps