Photosynthesis

Non-Cyclic Electron Flow

1) takes place in the thylakoid of the chloroplast, where cholorophyll is housed

2) sunlight is captured by chlorophyll and enzymes in the thyalkoid membrane, where it is turned into NADPH and ATP

3)inside the thylakoid we have PS2 which absorbs 680 lambda of light

4) this radiation splits the H2O (within the plant) into H+ and O2 resulting in free electrons and protons as O2 leaves the plant (photolysis)

5) charged electrons then travel to the PQ while the H+ stays in the lumen of the thylakoid (as electrons travel to PQ protons are pumped into the thylakoid lumen from the stroma)

6) as the electron travels to B6F more protons are pumped into the lumen through the stroma

7) the electron goes to PC then PS1

8) PS1 can absorb 700 lambda of light and it again excites the electron

9) the electron continues to shuttle as it enters FD and then FNR

10) Lastly the electron reduces NADP to NADPH

11) Because of the exessive H+ in the thylakoid lumen the protons must leave the lumen because it is very acidic

12) Protons go through chemiosmosis where ADP is reduced to become ATP through the ATPase.

Calvin Cycle

The ATP and NADPH is used for the production of glucose in the Calvin Cycle

13) Rubisco combines  RuBP ( P-C-C-C-C-C-P) x3 with CO2 x3 to form (P-C-C-C-C-C-C-P) x3

14) it is then split to 3-phosphoglycerate (P-C-C-C) x6

15) ATP x6 is used to add a phosphate onto 3-phosphoglycerate to make it more stable to become 1,3-biphosphoglycerate (P-C-C-C-P) x6

16) 1,3-biphosphoglycerate is then oxidized as NADPH takes the P to become G3P

17) One of the G3P leaves the cycle 

18) the remaining (C-C-C-P) x5 goes through a series of steps to become the original RuBP (regeneration)

19) 3 ATP is oxidized to make G3P become RuBP (P-C-C-C-C-C-P) x3

20) Calvin cycle must run twice for 1 glucose to be made C6H12O6 <-- 6 carbons, G3P only has 3 carbons

Cyclic Electron Flow

-sometimes electrons use PS1 only

-electron is ejected from PS1 and passes FD --> B6F--> PC-->and back to PS1

-this pathway generates a proton gradient for synthesis of ATP but does not generate NADPH.