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13.3 The light-dependent stage of photosynthesis - Coggle Diagram
13.3 The light-dependent stage of photosynthesis
ATP and NADPH are transferred to light-independent stage
Cyclic photophosphorylation
Only involves photosystem I
ATP is formed
No NADPH is formed
Light energy is absorbed by photosystem I and passed to reaction centre
This light energy excites an electron in chlorophyll a to a higher level and the e- is emitted from chlorophyll molecule - photoactivation
Electron is captured by electron acceptor in thylakoid membrane
Electron is passed down electron transport chain via electron carriers in a series of redox reactions
Electron loses/releases energy as it is passed down
This released energy is used to pump H+ from stroma into thylakoid lumen and establish proton gradient
Protons flow back into stroma and power ATP synthase
Non-cyclic photophosphorylation
Energy from electron emitted from photosystem II is used to form ATP, and electron is passed to photosystem I
Energy from electron emitted from photosystem I is passed to NADP to form NADPH
Photosystem II gains back its lost electron from photolysis of water
Photolysis of water
Photosystem II contains an oxygen-evolving complex
H2O --> 2H+ + 2e- + 1/2 O2
Oxygen diffuses out of the chloroplast as a waste product
NADPH is formed from two of the electrons emitted from photosystem I and two H+ from photolysis combined with NADP