THE OVERALL EQUATION OF PHOTOSYNTHESIS AND THE SOURCE OF MOLECULAR OXYGEN: TUTORIAL ANALYSIS OF THE FORMAL PARADOX

Cover Page

Cite item

Full Text

Open Access Open Access
Restricted Access Access granted
Restricted Access Subscription Access

Abstract

In the article, we discuss the seeming paradox associated with molecular oxygen being evolved during photosynthesis. After van Niel's work in the early 1930s, it became clear that in oxygenic photosynthesis, molecular oxygen originates from the water oxygen atoms rather than those of carbon dioxide. At the same time, one can see from the overall equation of photosynthesis, n CO2 + n H2O —  hν → (C H2O)n + n O2, that the amount of photosynthetically produced oxygen exceeds the amount that could be provided by the water molecules involved in the reactions. This paradox can be resolved by a detailed (although not going beyond the basic course of biochemistry) analysis of the light and dark reactions of photosynthesis leading to the incorporation of a carbon from dioxide molecule into a carbohydrate and the formation of molecular oxygen. However, despite this paradox can be solved simply enough, it is not widely discussed, and the solution does not seem quite evident. Among the reasons for this, the fact that the dark reactions of photosynthesis are commonly written schematically both in scientific and educational literature, without carefully specifying all the components included in the reactions, may play a role. We believe that the analysis of this paradox and the underlying physico-chemical principles of photosynthesis can be useful for students specializing in biochemistry as a spectacular educational and methodological example.

About the authors

V. V Ptushenko

Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University; Emanuel Institute of Biochemical Physics, Russian Academy of Sciences

Email: ptush@belozersky.msu.ru
Moscow, Russia; Moscow, Russia

References

  1. Ожегов, С. И. (2012) Толковый словарь русского языка. Ленинградское издательство, Санкт-Петербург.
  2. (2022) Парадокс. Большая российская энциклопедия: научно-образовательный портал, URL: https://bigenc.ru/c/paradoks-1a2c58/?v=4527101 (обращение 12.09.2025).
  3. De Saussure, N. T. (1804) Chemical research on vegetation [in French], Nyon.
  4. Van Niel, C. B. (1949) The comparative biochemistry of photosynthesis. Am Sci, 37, 371-383.
  5. Ruben, S., Randall, M., Kamen, M., and Hyde, J. L. (1941) Heavy oxygen (O18) as a tracer in the study of photosynthesis, J. Am. Chem. Soc., 63, 877-879, https://doi.org/10.1021/ja01848a512.
  6. Ленинджер А. (1976) Биохимия: молекулярные основы структуры и функции клетки, Мир, Москва.
  7. Эллиот В., Эллиот Д. (2002) Биохимия и молекулярная биология, МАИК Наука/Интерпериодика, Москва.
  8. Voet, D., and Voet, J. G. (2011) Biochemistry, John Wiley & Sons.
  9. Пасечник В. В., Каменский А. А., Криксунов Е. А., Швецов Г. (2018) Биология. Введение в общую биологию. 9 класс. Дрофа, М.
  10. Baeyer, A. (1870) On water removal and its significance for plant life and fermentation [in German], Berichte Dtsch. Chem. Gesellschaft, 3, 63-75.
  11. Spoehr, H. A. (1916) The theories of photosynthesis in the light of some new facts, Plant World, 19, 1-16.
  12. Butlerow, A. (1861) Formation of a sugar-like substance by synthesis [in German], Justus Liebigs Ann. Chem., 120, 295-298, https://doi.org/10.1002/jlac.18611200308.
  13. Van Niel, C. B., and Muller, F. M. (1931) On the purple bacteria and their significance for the study of photosynthesis, Recl. Des Trau. Bot Neerlandais, 28, 245-274.
  14. Виноградов А., Тейс Р. (1941) Изотопный состав кислорода разного происхождения (кислород фотосинтеза, воздуха, CO2, H2O), Докл. Акад. Наук СССР, 497-501.
  15. Brown, A. H., and Frenkel, A. W. (1953) Photosynthesis, Annu. Rev. Plant Biol., 4, 23-58, https://doi.org/10.1146/annurev.pp.04.060153.000323.
  16. Arnon, D. I. (1971) The light reactions of photosynthesis, Proc. Natl. Acad. Sci. USA, 68, 2883-2892, https://doi.org/10.1073/pnas.68.11.2883.
  17. Junge, W. (2019) Oxygenic photosynthesis: history, status and perspective, Q. Rev. Biophys., 52, e1, https://doi.org/10.1017/S0033583518000112.
  18. Davis, G. A. and Kramer, D. M. (2020) Optimization of ATP synthase c-rings for oxygenic photosynthesis, Front. Plant Sci., 10, 1778, https://doi.org/10.3389/fpls.2019.01778.
  19. Munekage, Y., Hashimoto, M., Miyake, C., Tomizawa, K.-I., Endo, T., Tasaka, M., and Shikanai, T. (2004) Cyclic electron flow around photosystem I is essential for photosynthesis. Nature, 429, 579, https://doi.org/10.1038/nature02598.
  20. Breyton, C., Nandha, B., Johnson, G. N., Joliot, P., and Finazzi, G. (2006) Redox modulation of cyclic electron flow around photosystem I in C3 plants, Biochemistry, 45, 13465-13475, https://doi.org/10.1021/bi061439s.
  21. Tikhonov, A. N. (2015) Induction events and short-term regulation of electron transport in chloroplasts: an overview, Photosynth. Res., 125, 65-94, https://doi.org/10.1007/s11120-015-0094-0.
  22. Renger, G. (2007) Overview of primary processes of photosynthesis, Prim. Process Photosynth. Part, 1, 5-35, https://doi.org/10.1039/9781847558152-00001.
  23. Bassham, J. A., Benson, A. A., Kay, L. D., Harris, A. Z., Wilson, A. T., and Calvin, M. (1954) The path of carbon in photosynthesis. XXI. The cyclic regeneration of carbon dioxide acceptor, J. Am. Chem. Soc., 76, 1760-1770, https://doi.org/10.1021/ja01636a012.
  24. Sharkey, T. D. (2019) Discovery of the canonical Calvin-Benson cycle, Photosynth. Res., 140, 235-252, https://doi.org/10.1007/s11120-018-0600-2.
  25. Кнорре А. Ф., Мызина С. А. (1998) Биологическая химия: Учеб. для хим., биол. и мед. спец. вузов. Высшая школа.
  26. Whitmarsh, J., and Govindjee. (1999) The photosynthetic process, Concepts Photobiol. Photosynth. Photomorphogenes, Springer, p. 11-51, https://doi.org/10.1007/978-94-011-4832-0_2.
  27. Stirbet, A., Lazár, D., Guo, Y., and Govindjee, G. (2020) Photosynthesis: basics, history and modelling, Ann. Bot., 126, 511-537, https://doi.org/10.1093/aob/mcz171.
  28. Bassham, J. A., and Krause, G. H. (1969) Free energy changes and metabolic regulation in steady-state photosynthetic carbon reduction, Biochim. Biophys. Acta, 189, 207-221, https://doi.org/10.1016/0005-2728(69)90048-6.
  29. Govindjee, Bassham, H., and Bassham, S. (2016) Remembering James Alan Bassham (1922-2012), Photosynth. Res., 128, 3-13, https://doi.org/10.1007/s11120-015-0201-2.

Supplementary files

Supplementary Files
Action
1. JATS XML
Download

Copyright (c) 2025 Russian Academy of Sciences

Согласие на обработку персональных данных

 

Используя сайт https://journals.rcsi.science, я (далее – «Пользователь» или «Субъект персональных данных») даю согласие на обработку персональных данных на этом сайте (текст Согласия) и на обработку персональных данных с помощью сервиса «Яндекс.Метрика» (текст Согласия).