Light dependant reaction

• Photolysis of water

  A photon of light provides energy o the water splitting enzyme to split h2o into

  • H+ ions which accumulate into the thylakoid space
  • 1/2 o2 which is released into the atmosphere
  • e- which is donated to photosystem 2 (reaction centre)
• Light dependant reaction

  Diagram

  
• Box 2 in diagram

  • a photon of light excites electrons in photosystem 2 to a higher energy state
  • The electron binds to an electron acceptor
• the electron transport chain

  • high energy electron are passed between a series of electro carries (PC and PQ)
  • a cytochrome complex harnesses energy from the e- to actively pump h+ ion from the stroma through the thylakoid membrane into the thylakoid space
  • this sets up a proton gradient in the thylakoid space
• What a the electron caries

  PQ and PC
• what is water broken down into by the water splitting enzyme

  H+ ions. 1/2 o2 and e-
• box 4 of diagram

  • low energy electron arrive at photosystem 1
  • photon of light excites electrons to a higher energy site
  • the electron binds onto an electron acceptor
• box 5 on diagram

  NADP reductase- reduces NADP using high energy electrons from ps1 to form NADPH which is a high energy electron carrying molecule

  ferredoxin provides electrons to NADP reductase
• what is NADPH

  a high energy electron carrying molecule
• chemiosmosis

  high h+ ions conc in thylakoid space compared to in the stroma

  they move from high to low concentration through atp synthase via facilitated diffusion into the stroma

  there movement results in the phosphorylation of ADP into ATP