Solution to PS 5 #3
a) Yes. When DCMU blocks electron flow, PII in the P680*
state will not be reoxidized to the P680+ state, which is equired
as an acceptor of electrons from H2O. if H2O is not oxidized by P680+ then
no O2 will be produced. in the absence of elecetron flow to the Cytochrome
bf complex, no protons will be translocated across the membrane.
Without a pH gradient no ATP synthesis will be possible.
b) External electron acceptors for PSII will permit P680 to be reoxidized
to P680+ and will restore O2 evolution. No electrons will flow through
the cytochrome bf complex, however, so that no photophosphorylation will
occur.
Return to Problem Set #5