biology unit 4 [photosynthesis]

Light dependent reaction [grana/thylakoids]

• light energy excites the electron in the chlorophyll and raises its energy level
• electron passes down an electron transfer chain and goes through a series of redox reactions
• as this happens, energy is released which is used to make ATP from ADP+Pi
• electron lost from chlorophyll needs to be replaced
• water is split by light energy in photolysis into 2H⁺+ 2e^-+ 1/2O₂
• the electrons replace the ones lost from the chlorophyll, the hydrogen and an associated electron are used to reduce a hydrogen carrier NADP to make a reduced NADP
• the oxygen is given off as a useful waste product

Light independent reaction [stroma]

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