Question

From where energy is provided for the synthesis of ATP in PS II?

Answer 1

Photosystem II:

1. Photosystems are light-absorbing pigments organized in functional arrays on thylakoid or bacterial membranes.
2. Chlorophyll and accessory pigments make up the majority of the pigments in the photosystem.
3. Chlorophyll's primary role is to collect light energy in the form of photons in order to perform photosynthesis, whereas accessory pigments, as their name suggests, work as secondary light-absorbing pigments that improve chlorophyll's overall effectiveness. Carotenoids are an example of an accessory pigment.
4. Photosystem II absorbs light at a wavelength of 680nm, thus the photosystem is abbreviated as PS II.
5. Chlorophyll molecules at the reaction centre, pheophytin (pheo), plastoquinone (PQ), cytochrome-b6f complex (cyt b6f), and plastocyanin are the primary elements of PSII.
6. The oxygen-evolving complex is linked to PSII.
7. $2{\mathrm{H}}_2\mathrm{O}\to 4{\mathrm{H}}^{+}+{\mathrm{O}}_2+4{\mathrm{e}}^{-}$
8. Because this reaction occurs on the inner side of the thylakoid membrane, the protons produced are trapped in the thylakoid lumen.
9. Protons are transferred across the membrane as electrons flow through photosystems.
10. This gradient is significant because its breakdown results in energy release.
11. Proton gradient provides energy for the synthesis of ATP in PS II.