In non-cyclic photophosphorylation (the Zscheme), electrons travel from Photosystem I to Ferredoxin and then to FNR to reduce NADP+ into NADPH. In cyclic photophosphorylation, electrons are cycled back from Ferredoxin to the Cytochrome B6f complex; therefore, FNR is not involved in the cyclic pathway. The stroma lamellae membranes possess PS I but lack PS II and the NADP reductase enzyme (FNR). FNR is not the primary electron acceptor from PS II, but is associated with the end of the electron transport chain after Photosystem I