Light Dependent Reaction Flashcards
What are the stages of the light Dependent reaction?
There are photosystems all over the thylakoid membranes, absorbing light energy
* They are arranged in pairs; PSIl comes first, then PSI
* In non-cyclic photophosphorylation, the following happens;
* When the chl-a in the reaction centre of PSII absorbs light, e are “excited” to a higher energy level, where they are passed along an electron transport chain (ETC)
* The carriers are iron-containing proteins attached to the thylakoids
* When they accept e, they are REDUCED & when they pass them on, they are
OXIDISED
* The energy released as the e pass along is used to phosphorylate ADP
ADP + Pi -> ATP. This is photophosphorylation
* The e that left PSIl are replaced by the splitting of nearby water molecules
(PHOTOLYSIS)
- PSI is also absorbing light, and e are being excited (replaced by the ones arriving from PSIl)
* Again, these e- pass along an ETC
At the end, a substance called ferredoxin (iron protein complex) passes the e, along with the Ht from the water, to a substance called NADP
* This causes the NADP to become reduced (“Reduced NADP”/NADPH/NADPH2)
