photosynthess chapter 14 autotrophc organsms heterotroph autotrophs produce organc nutrents from Chemoautotrophs use energy from norganc molecules. hotoautotrophs use radant energy to make organc compounds photoautotrophs photosynthess found n plants algae protsts some prokaryotes harvests energy from the sun carbohydrates photoautotrophs photosynthess low energy electrons converted to hgh energy electrons used to chan carbon atoms together electron donors HS H cyanobactera
plant structure leaves eudcots two layers of palsade spongy stomata monocots sngle layer of monocot palsade spongy eudcot 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 Thylakod Mesophyll 1 μm Leaf cross secton s Ven Stomata uter Inter Inner Mesophyll cell 0 μm chloroplasts photosynthess outer nter nner stroma thylakod grana thylakod Stroma Thylakod Granum Thylakod uter Inter Inner basc reacton aerobc respraton n reverse 6 + 1 H + energy C 6 H 1 6 + 6 + 6 H Reactants: 6 1 H roducts: C H 6 1 6 6 H 6 becomes reduced 1 μm Energy + 6 + 6 H C H + 6 6 1 6 becomes oxdzed
photosynthess lght-dependent energy from sunlght absorbed stored as AT and NADH lght-ndependent converted to carbs uses energy from AT and NADH H Reactons NAD+ AD + AT NADH [CH ] (sugar) harvestng lght wavelength shorter wavelength = hgher energy absorpton photon absorbed by molecule electron excted 10 5 nm 10 nm 1 nm 10 nm 106 nm (109 nm) 10 m Gamma rays X-rays UV Infrared Vsble lght Mcro- waves 1 m Rado waves 80 450 500 550 600 650 700 750 nm Shorter wavelength Hgher energy Longer wavelength Lower energy harvestng lght 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 photosystems photosynthetc unt antenna reacton-center hoton - harvestng complexes hotosystem Reacton- center complex e STRMA rmary electron acceptor hytol tal Thylakod Transfer of energy Specal par of chlorophyll a molecules gment molecules THYLAKID SACE (INTERIR F THYLAKID)
1 photosystems rmary acceptor e 680 photosystem II boosts electrons energy level to mdpont reacton center (680) photosystem I boosts electrons energy level to above NAD + reacton center (700) Z scheme - splttng water photosystem II lght-harvestng complex II contans most of the antenna pgments lght energy transmtted to core of S gment molecules hotosystem II (S II) splttng water photosystem II transfers electron to pheophytn prmary electron acceptor pheo + 680+ (powerful oxdzng agent) pheo- donates electron to plastoqunone wth next photon, plastoqunone reduced to plastoqunol (QH) photolyss requres 4 electrons ( for each atom) producton of NADH brdgng the gap QH -> cytochrome b6f (multproten complex) electrons passed to plastocyann plastocyann passes electrons to 700 + Thylakod Granum Thylakod 1 μm
producton of NADH photosystem I LHC1 700 transfers electron to A0 700 + electron replaced by ncomng electron passed from lumen sde to stroma sde ferredoxns nteract wth ferredoxn NAD + reductase FAD group - accepts e - NADH powerng the C cycle STRMA (low H+ concentraton) THYLAKID SACE (hgh H+ concentraton) STRMA (low H+ concentraton) hotosystem II H 1 1/ 4 H+ + H+ q Thylakod Cytochrome complex 4 H+ c AT synthase hotosystem I AD + H+ Fd AT NAD+ reductase NADH NAD+ + H+ To Fgure 10.17 Mtochondron MITCHNDRIN STRUCTURE CHLRLAST STRUCTURE actual locatons SI and S II are not located n the same areas SII s located n the stacked grana SI s located outsde stacked grana Inter H+ Dffuson Thylakod Inner Electron transport chan Thylakod Matrx AT synthase Stroma Key Hgher [H+ ] AD + H+ AT Lower [H+ ] GRANA
photophosphorylaton producton of AT ph gradent establshed AT synthase pumps H + out of lumen noncyclc phosphoryaton cyclc photophosphorylaton sometmes electrons from ferredoxn passed back to cytochrome complex pump H + nto lumen Regeneraton of acceptor AD x Rbulose bsphosphate (RuB) Co (one at a tme) 1 Rubsco x short-lved ntermedate CALVIN CYCLE x6 Carbon fxaton -hosphoglycerate x6 6 AT 6 AD 1,-bsphosphoglycerate AT x5 Glyceraldehyde - phosphate (G) x6 Glyceraldehyde - phosphate (G) 6 NADH 6 NAD + 6 Glyceraldehyde - phosphate (G) Reducton carbohydrate synthess GA molecules exported nto cytoplasm exchanged for phosphate H used to synthesze sucrose can reman n chloroplast Reactons: hotosystem II Electron transport chan hotosystem I Electron transport chan NAD+ AD + RuB -hosphoglycerate 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 AT NADH G Starch (storage) Sucrose (export)
C4 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 AT bundle yruvate sheath (C) cells CAM plants crassulacean acd metabolsm open stomata at nght fx close stomata durng day use from CAM pathway examples orchds, bromelads, pneapple, ferns, cycads, some dcots ncorporated 1 (carbon fxaton) CAM rganc acd Nght Sugar released to the cycle Day Vascular tssue Sugar Temporal separaton of steps