BRAINCAKENon-cyclic Photophosphorylation
Non-cyclic photophosphorylation involves both PSI and PSII. The chlorophyll molecules at the reaction centres absorb light. Electrons are passed to electron carriers. A proton gradient is set up between the stroma and the inside of the thylakoid by actively transporting hydrogen ions into the thylakoid space using the energy from the electrons. The proton gradient is used to synthesise ATP by chemiosmosis.
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Key terms in this lesson
- ATP
- Adenosine triphosphate, the universal energy currency of cells, which releases energy for cellular reactions when hydrolysed to ADP and inorganic phosphate.
- Thylakoid
- A flattened, membrane-bound disc within a chloroplast, stacked into grana, where the light-dependent reactions of photosynthesis occur.
- Stroma
- The fluid matrix of the chloroplast in which the light-independent reactions (Calvin cycle) of photosynthesis take place.
- Chlorophyll
- The main photosynthetic pigment, which absorbs light energy, exciting electrons that are used in the light-dependent reactions.
- Chemiosmosis
- The synthesis of ATP by ATP synthase using the energy of a proton (hydrogen ion) gradient across a membrane.
More in Energy for Biological Processes
- ATP
- Chloroplasts
- Photosynthetic pigments
- Photosystems
- Cyclic Photophosphorylation
- Chemiosmosis
- Calvin Cycle
All 8 lessons in Energy for Biological Processes · All OCR A-level Biology topics