Require light in the visible range spectrum, convert light energy to chemical energy, produce ATP & NADPH+H, by product: O2
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Light independent reactions
Don't require light, must be preceded by the light reactions, use ATP and NADPH+H from the light reactions, carbon fixation takes place, sugars/ carbohydrates are produced
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Stroma
Aqueous layer where both light independent reactions and carbon fixation occurs
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Envelope
2 membranes with inter-membrane space, inner membrane is impermeable to most ions/ molecules
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Thylakoid disks and grana
Disk-like structures stacked into grana, centre of each thylakoid is the lumen
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Thylakoid membrane
Where light dependant reactions occur
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How is the light captured?
By pigments
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Photosystem 1
Reaction centre: Chl a, primary e- acceptor: Fe-S protein, final e- acceptor: Ferredoxin, responsible for photo reduction
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Photosystem 2
Reaction centre: Chl a, primary e- acceptor: Pheophytin, final e- acceptor: Plastocyanin, responsible for photolysis (photooxidation) and photophosphorylation
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Describe photooxidation
Pheophytin accepts e- from P680* (PS2) oxidising it to P680+, then e- passed down ETC, P680+ (oxidised PS2) is a strong oxidant and pulls e- from H2O, H2O split and 1H and 1O2 is released into the lumen
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What molecule is the e- from pheophytin passed go in order for it to enter the ETC?
Plastoquinone
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Plastoquinone
Bound to P680 (PS2) until 2H+ are pumped from the stroma (reducing it to plastoquinol) making it dissociate and able to physically carry the 2H+ and the 2e- through the thylakoid membrane
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After the plastoquinol has diffused through the thylakoid membrane, what happens?
The 2e- are passed to Cytb6F and the 2H+ are released into the lumen, at the same time more H+ are been pumped into lumen, Cytb6F passes 2e- to plastocyanin which is a mobile e- carrier and takes it to P700 (PS1)
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Where has the build up of H+ in the lumen during the ETC come from?
Pumped from stroma into lumen with the plastoquinone and the Cytb6F and also from being released into the lumen from photolysis
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What does this build up of H+ allow?
Creates a proton gradient from stroma to lumen, excess H+ return to stroma via ATP synthase, producing ATP, creating at least 2ATP molecules from 1H+ ion (chemiosmotic synthesis of ATP)
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What happens once the P700 receives the 2e- from plastocyanin?
P700 becomes reduced and electrons are accepted by Fx and passed to ferredoxin, reduced ferredoxin passed e- to NADP+, product: NADPH+H+
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Other cards in this set
Card 2
Front
Light independent reactions
Back
Don't require light, must be preceded by the light reactions, use ATP and NADPH+H from the light reactions, carbon fixation takes place, sugars/ carbohydrates are produced
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