Photosynthesis

Non-Cyclic Electron Flow: (light reaction)

• Photosystem II begins the reaction once the photons hit the reaction centre where it causes H20 to split into its elements (photolysis – by z protein) 
• H+ remains while the electrons travel to PQ in the process of a redox reaction;
• PQ  pumps in protons into the lumen
• Electrons then go to b6f, whereby more protons are pumped into lumen 
• Electrons then go to PC before going to Photosystem I
• Photosystem I  excites the electron before passing it on to Ferredoxin (Fd) 
• At Fd the electrons reduce NADP to become NADPH, before attaching to FNR (ferredoxin-NADP reductase)
•  Since a large number of protons are present in the thylakoid lumen, chemiosmosis, must take place in order to move the protons to the chloroplast stroma – a process in which ATP is synthesized form ADP.

Cyclic Electron Flow

• Occurs when there is not enough light
• It starts at PSI and when light hits it electrons travel through to Fd, B6F, PC, and then back to PSI
• ATP is made in this process

Calvin Cycle: (dark reaction)

• The production of glucose in the production of carbon fixation.
• RuBP (Rubulose Biphosphate), a 5-carbon sugar, gets CO2 from the atmosphere to form a 6-carbon sugar 
• Thereafter the 6-carbon sugar divides to form a 3-carbon sugar also known as 3-Phosphoglycerate.
• The 3-Phosphoglycerate is reduced, as an ATP molecule loses a phosphate to form 1,3 -Biphosphoglycerate 
• 1,3 Biphosphoglycerate is oxidized by an NADPH to for G3P (Glyceraidehyde-3-phosphate) 
•  One G3P leaves cycle in order to form glucose (2 G3P needed per glucose molecule)
• The remaining 5 G3P continue along the cycle in order to RuBP which is the initial molecule in this cycle