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ATP synthesis is driven by H+ gradient H+ gradient formation H+ H+ H+

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Presentation on theme: "ATP synthesis is driven by H+ gradient H+ gradient formation H+ H+ H+"— Presentation transcript:

1 Similarities between photophosphorylation and oxidative phosphorylation
ATP synthesis is driven by H+ gradient H+ gradient formation H+ H+ H+ H+ H+ e- Proton pump e- e- ATP synthase Energy from electrons is used for H+ translocation ATP H+ ADP+Pi

2 Differences between photophosphorylation and oxidative phosphorylation
Energy source: electrons NADH FADH2 Energy source: light H+ H+ H+ H+ H+ e- Proton pump NADP+ NADPH O2 H2O ATP synthase ATP H+ H+ By-product: water ADP+Pi By-product: electrons

3

4 (photophosphorylation)
Photosynthesis: The light reactions (photophosphorylation)

5 Chlorophyll (or other pigments) absorbs light energy and conserve it as ATP and NADPH.
Not all photosynthetic organisms use H2O as electron donor in photosynthesis; thus not all of them produce O2 while they produce ATP and NADPH. There are two types of photosynthesis: oxygenic (producing oxygen) photosynthesis and anoxygenic (not producing oxygen) photosynthesis. Only organisms with two photosystems can do oxygenic photosynthesis. At lease half of the photosynthsis in this world is done by microorganisms (algae, photosynthetic eukaryotes and photosynthetic bacteria).

6 p724

7 Outer membrane Thylakoid membrane (lamellae) Inner membrane grana lumen stroma

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9 Chloroplast has photosystems with closely arranged chlorophyll

10 Cyanobacteria & red algae also contain similar structures called phycobilisome to facilitate light absorption p727

11 The major light absorbing pigment in higher plants
Alternating single and double bonds give strong absorption in the visible light p726

12 The accessory pigment in bacteria and algae

13 What wavelength of light chlorophyll absorbs?

14 Chlorophylls can cover part of the spectrum – blue and red

15 The part of spectrum covered by chlorophylls coincides with the action spectrum of photosynthesis

16 Accessory pigment: the red-orange -carotene

17 Accessory pigment: lutein (the red-orange isoprenoid)

18 b-carotene and lutein can help plant absorb more light

19 Phycoerythrin and phycocyanin can absorb light that other pigments cannot absorb

20 Anoxygenic photosynthesis
(ferredoxin) (pheophytin) (restore RC to original state) (restore RC to original state) (PSII) (PSI) p731

21 The Z scheme of oxygenic photosynthesis
(special form of chlorophyll) (phylloquinone) (pheophytin) (plastoquinone) Green bacteria type Purple bacteria type p733

22 (A1)

23 PSI and PSII on thylakoid membrane are separated to prevent Excition Larceny
LHCII holds grana together p736

24 Granal stacking by LHCII is regulated by light intensity
High light [PQH2] [PQ] Low light [PQH2] [PQ] ATP Protein PPase Protein kinase LHCII -Thr-OH -Thr- P ADP Pi nonappressed appressed

25 Cytochrome b6f complex p737

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27 Oxidative phosphorylation and photophosphorylation has something in common in cyanobacteria

28 Oxygen-evolving complex (water-splitting complex)
D2 D1 QA QB Fe Pheo Pheo P680 e e e e Tyr e e e e Mn e e Mn 4H+ O2 e e e e e Mn e Mn 2H2O Oxygen-evolving complex (water-splitting complex) p739

29 N P p741

30 N N N p742

31 bacteriorhodopsin p744

32 All-trans-retinal 13-cis-retinol Proton transport

33 Chloroplast from higher plants is probably evolved from endosymbiotic bacteria (prochlorophytes)
Chloroplast from red algae is probably evolved from cyanobacteria p1062

34 p723


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