Light-dependent reactions of photosynthesis

The light-dependent reactions of photosynthesis

In the light-dependent reactions of photosynthesis, the energy of the light is converted into chemical energy. Living beings gain portable and short-term storable chemical energy by building up units of the universal "energy currency" ATP and storing reduction equivalents in the form of NADPH.


The light-dependent reactions take place in the thylakoid.

  • The proteins involved are stored in the thylakoid membrane.
  • The separation of a thylakoid compartment allows the proton concentration in the lumen to increase.
  • Sunlight and water enable the proteins of the thylakoid membrane to build up ATP and NADPH.
  • 1.25 molecules of ATP are formed per absorbed photon (if you convert NADPH to ATP in a ratio of 1: 3).
  • An important by-product of this reaction is oxygen.

Related Links:

  • The light reactions of photosynthesis
  • Photosystem I and II and the Light Reaction


Senior, A. E .; Nadanaciva, S .; Weber, J. (2002):The molecular mechanism of ATP synthesis by F1F0-ATP synthase. In: Biochim. Biophys. Acta. 1553, 188-211
Hervas, M .; Navarro, J. A .; De La Rosa, M. A. (2003):Electron transfer between membrane complexes and soluble proteins in photosynthesis. In: Acc. Chem. Res.. 36, 798-805
Moser, C. C .; Page ,, C. C .; Cogdell, R. J .; Barber, J .; Wraight, C. A .; Dutton, P. L. (2003):Length, time, and energy scales of photosystems. In: Adv. Protein Chem.. 61, 71-109

Video: Calvin Cycle (January 2022).