Photosynthesis occurs in the chloroplasts of the plant cells.
Photosystem I (PSI), Photosystem II (PSII), and ATP Synthase.
Photosynthetic Inhibitors control many broadleaf and some grass weeds. In general, these herbicides inhibit photosynthesis by binding to D1 proteins of the photosystem II complex in chloroplast thylakoid membranes. Herbicide binding at this protein blocks electron transport and stops CO2 fixation and production of energy needed for plant growth. The death of plants, however, does not occur primarily from photosynthates depletion but rather from an indirect effect on other processes. Blocking electron transport in PSII systems promotes the formation of highly reactive molecules that initiate a chain of reactions causing lipid and protein membrane destruction that results in membrane leakage allowing cells and cell organelles to dry and rapidly disintegrate. In addition, some PSII Inhibitors affect other plant processes such as carotenoid biosynthesis and synthesis of anthocyanin, RNA, and proteins.
PSI and PSII absorb light through pigments (explained below).
ATP synthase (ATPase)
3--Bacteria that carry out oxygenic photosynthesis have 2 photosystems(PSI and PSII) with 2 reaction centers (RCI and RCII).
The new structures of PSI and PSII from ..
Determination of efficient (photosynthetically speaking) light sources is important for several reasons. Economy in the costs of maintaining a coral reef aquarium certainly is a concern, but the health of zooxanthellae and hence their animal host should be of primary importance. Aesthetic concerns, such as the promotion of coral coloration through expression of fluorescent proteins and non-fluorescent chromoproteins, are of interest to many.
Difference between Photosystem I and Photosystem II ..
In contrast, at room temperature, energy transfer processesbetween the various photosynthetic complexes result in very similarfluorescence emissions, which mainly consist of fluorescence photonsemitted by PSII hindering a discrimination based on spectral ROIs(regions of interest).