Goals of photosynthesis
- convert light energy to chemical energy (ATP)
- produce reducing equivalents (NADPH)
- convert CO2 to sugar (Carbon Fixation)
what is the source of electrons?
water
antenna pigments
capable of absorbing light but cannot convert it to chemical energy - pass it on to chlorophyll a pair
Photosystem I
energizes and transfers e- that are donated to NADP+
Photosystem II
oxidizes water molecules and donates the energized e- to e- carriers that eventually reduce PSI
cytochrome b6f complex
passes e- from PSII to PSI
Z scheme reaction
H2O -> PSII ->PQ -> cyt bf -> PC -> PSI -> Fd -> FNR -> NADP+
how many steps are there in water-oxidizing clock
5 oxidation states
Manganese Cluster
stabilizer protein that allows for series of oxidation to occur next to PSII
first and last e- carriers?
first: chlorophyll a
last: ferredoxin (2 pathways)
Noncyclic e- transport
FNR to make NADPH
Cyclic e- transport
PQR drives ATP synthesis without making NADPH