Photophosphorylation is the process of creating ATP using a Proton gradient created by the Energy gathered from sunlight. The process of creating the Proton gradient resembles that of the electron transport chain of Respiration. But since formation of this proton gradient is light-dependent, the process is called Photophosphorylation.
Chemiosmosis - Chemiosmosis is the process of using Proton movement to join ADP and Pi. This is accomplished by enzymes called ATP synthases or ATPases. The CF1-ATPase of the Thylakoid membrane is shown on the left. As protons pass through this enzyme ADP and Pi are joined to make ATP. The movement of the Protons through this enzyme provides the Energy needed to make ATP.
Noncyclic Photophosphorylation really refers to the ATP generated by Protons moved across the Thylakoid membranes during the Z-scheme. The Cytb6-f complex acts as an electron transport chain. As the electrons lose Energy (during a series of re/dox reactions) Protons are moved into the Thylakoid space. This Proton gradient can be used to generate ATP chemiosmotically.
During Cyclic Photophosphorylation the electrons are recycled, hence the name cyclic photophosphorylation. The excited electrons resulting from the absorption of light in photosystem I are received by the primary electron acceptor and then transferred to the cytb6-f complex which acts as an electron transport chain. The electrons return back to the reaction center of Photosystem I, where the cycle is ready to start all over. The electrons are using to translocate Protons which the ATPase uses to synthesize ATP. No reduction of NADP+ occurs in Cyclic Photophosphorylation.
During the movement of electrons shown in red, H+ moves across the membrane.
The movement of electrons "drives" the reactions shown in blue.