ELECTRON TRANSPORT Flashcards
Photosystem
light-harvesting complex and reaction center
Light-harvesting complex
pigments molecules bonded to proteins
Reaction center
special pair of chlorophyll a
electron acceptor
Location of PSII and PSI
Thylakoid membranes
Z-scheme
cooperation of PSII and PSI in the transfer of electrons from water to NADP+
Proton hits chlorophyll (excited) and then loss electron (oxidized chlorophyll) (ground state) H+ and O2
PSII
P680+ is strong oxidant
strong enough to pull electrons from H2O
PSI
P700 is strong reductant
strong enough to donate electrons to NADP+
Special pair of chlorophyll a
P680 and P700
What connects PSI and PSII
electron transport chain
Plastoquinone (PQ)
small molecule and mobile electron carrier (chemical)
PSII to Cyt bef
Plastocyanin (PC)
small protein and mobile electron carrier
Cyt bef to PSI
Linear electron transport
PSII –> Cyt bef –> PSI
LCH complex
PSII surrounded by LCHII complex
PSI surrounded by LCHI complex
Oxygen evolving complex*
PSII luminal surface
generates O2
Mn
nutrients*
Nitrogen and magnesium- chlorophyll synthesis
Mn- oxygen evolving complex
Fe- enzyme activity in chlorophyll synthesis and
Electron transfer in PSII
Light converts reaction chlorophyll P680 to P680
Electron leaves P680 forming P680+
The electron is transferred to Pheophytin forming Pheo-
Pheo- passes electron to Qa to produce Qa-
Qa- passes the electron to Qb to produce Qb-
First electron acceptor in PSII*
Pheophytin
Plastoquinone –> plastoquinol
PQ2- binds to protons from the stroma to from PQH2
First half Q cycle
PQH2 delivers two protons (H+) to lumen*, one electron to PC. PQ returns to PSII
Second half Q cycle
another PQH2 delivers two protons to lumen, one electron to PC. PQ, two electrons and two protons regenerate PQH2 which cycles agin
Ferrodoxin*
transfers electrons via ferredoxin: NADP+ reductase (FNR)
NADP+ and NADPH
ATP synthase
movement of protons form inside the lumen to the stroma across the thylakoid membrane
Synthesis of ATP from ADP and Pi
Appressed thylakoids
PSII mainly found in appressed regions
Cyt b6f