Light-dependent reaction

• Occurs on thylakoid membranes of chloroplasts.
• Photoionisation - First part of LDR - Light energy is absorbed by the chlorophyll raising electrons to a higher energy level. The electrons escape oxidising the chlorophyll
• Electron transfer chain - second part of LDR - Electrons loose energy as they move along carriers (oxidation-reduction of carriers). Energy is released and is used to actively transport hydrogen ions into the lumen of the thylakoid, establishing an electrochemical gradient. Electrons accepted by coenzyme NADP forming NADPH
• Facilitated diffusion of hydrogen ions via ATP synthase - Third part of LDR - condenses ADP + Pi into ATP. Electrons and hydrogen ions make NADPH in a reduction reaction

  ATP and NADPH are used in the light-independent reaction
• Photolysis: The absorption of light energy which causes a water molecule to split into an electron, hydrogen ion and an oxygen ion. The electrons reduce chlorophyll back to its original state to continue the process
• Products:

  • ATP
  • NADPH
  • Oxygen (waste product)
• Photophosphorylation: The production of ATP from the electrons and hydrogen ions from photoionisation and photolysis