BI110 Lecture Notes - Lecture 6: P680, Photosystem I, Photosystem
Document Summary
Module 30: photosynthesis ii: energy and sugars (lecture. Photosystem i: absorbs 700 nm light waves (p700) Photosystem ii: absorbs 680 nm light waves (p680) E- in p680 raised from ground state to excited state p680* P680* oxidized to p680* by primary e- acceptor pheophytin (pheo) P680 is reformed when p680* gains an e- from oxidation of h2: shuttles e- over to cytochrome complex, water splitting complex. Proton-motive force established across into stroma thylakoid membrane utilized to synthesize atp by chemiosmosis. Uses chloroplast atp synthase: h+ flows from thylakoid lumen. Photosystem i can also operate independently of photosystem ii by using cyclic electron flow. Electron transport from photosystem i to ferredoxin not followed by electron donation to the nadp+ reductase complex. Instead, reduced ferredoxin donates electrons back to the plastoquinone pool gets continually reduced and oxidized. Keeps moving protons across thylakoid membrane without involvement of photosystem ii.
