Similarities between photophosphorylation and oxidative phosphorylation e-e- Proton pump ATP synthase H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ ADP+Pi ATP

Differences between photophosphorylation and oxidative phosphorylation e-e- Proton pump ATP synthase H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ ADP+Pi ATP NADH FADH 2 NADP + NADPH O2O2 H2OH2O

p723

Photosynthesis: The light reactions (photophosphorylation)

 Chlorophyll (or other pigments) absorbs light energy and conserve it as ATP and NADPH.  Not all photosynthetic organisms use H 2 O as electron donor in photosynthesis; thus not all of them produce O 2 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).

p724

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

p729 Chloroplast has photosystems with closely arranged chlorophyll

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

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

p726 The accessory pigment in bacteria and algae

p725 The spectrum of electromagnetic radiation

p727 Chlorophylls can cover part of the spectrum – blue and red

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

Accessory pigment: the red-orange  -carotene p726

Accessory pigment: lutein (the red-orange isoprenoid)

 -carotene and lutein can help plant absorb more light

Phycoerythrin and phycocyanin can absorb light that other pigments cannot absorb

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

p733 The Z scheme of oxygenic photosynthesis Purple bacteria type Green bacteria type (pheophytin) (plastoquinone)

(A1)(A1)

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

Granal stacking by LHCII is regulated by light intensity

p737 Cytochrome b 6 f complex

p738 Oxidative phosphorylation and photophosphorylation has something in common in cyanobacteria

p739 Oxygen-evolving complex (water-splitting complex) can only accept one electron at a time In protein subunit D1 of the PSII reaction center; the immediate electron donor to P680 Loses one electron and proton at a time to P680; electrically neutral Tyr free radical (Tyr) is generated tyr then regain its electron and proton by oxidizing four Mn in the water splitting complex; each transfer corresponds to one photon absorption Here the Mn complex takes four electrons from a pair of water molecules; releasing 4H + and O 2 Goes to lumen

p741 P N

p742 N N N

p744 bacteriorhodopsin

All-trans-retinal13-cis-retinol Proton transport

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