Light dependent reaction - Photosynthesis

    Cards (6)

    • Light energy is absorbed by chlorophyll molecules in the chloroplast, exciting electrons in these molecules which are emitted from the molecules in a process called photoionisation
    • Lost "high-energy" electrons move along carriers of an electron transfer chain in the thylakoid membranes of the chloroplast, releasing energy as they go
    • The released energy is used to actively pump protons from the stroma into the thylakoid space against the proton electrochemical gradient
    • Protons then move back to the stroma through a channel in an enzyme called ATP synthase by facilitated diffusion, providing energy for ATP synthesis from ADP and Pi in a process called chemiosmosis
    • Electrons are used to reduce a molecule called NADP, requiring protons from the stroma
    • Water is split by photolysis at the start of the process, producing three products:
      • Electrons from this process replace those lost by chlorophyll
      • Oxygen diffuses out of the plant as a waste product
      • Protons may contribute to chemiosmosis or be used to reduce NADP
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