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Chloroplasts, containing thylakoids, visible in the cells of Ptychostomum capillare, a type of moss. A chloroplast (/ ˈ k l ɔːr ə ˌ p l æ s t,-p l ɑː s t /) [1] [2] is a type of organelle known as a plastid that conducts photosynthesis mostly in plant and algal cells.
Each photosystem has two parts: a reaction center, where the photochemistry occurs, and an antenna complex, which surrounds the reaction center. The antenna complex contains hundreds of chlorophyll molecules which funnel the excitation energy to the center of the photosystem. At the reaction center, the energy will be trapped and transferred to ...
In Chlamydomonas, the eyespot is part of the chloroplast and takes on the appearance of a membranous sandwich structure. It is assembled from chloroplast membranes (outer, inner, and thylakoid membranes) and carotenoid -filled granules overlaid by plasma membrane .
Like mitochondria, chloroplasts have a double-membrane envelope, called the chloroplast envelope, but unlike mitochondria, chloroplasts also have internal membrane structures called thylakoids. Furthermore, one or two additional membranes may enclose chloroplasts in organisms that underwent secondary endosymbiosis , such as the euglenids and ...
Chloroplasts have their own genome, which encodes a number of thylakoid proteins. However, during the course of plastid evolution from their cyanobacterial endosymbiotic ancestors, extensive gene transfer from the chloroplast genome to the cell nucleus took place. This results in the four major thylakoid protein complexes being encoded in part ...
Plastids function to store different components including starches, fats, and proteins. [9] All plastids are derived from proplastids, which are present in the meristematic regions of the plant. Proplastids and young chloroplasts typically divide by binary fission, but more mature chloroplasts also have this capacity.
Currently structures of the S1 state and the S3 state's have been published almost simultaneously from two different groups, showing the addition of an oxygen molecule designated O6 between Mn1 and Mn4, [13] [14] suggesting that this may be the site on the oxygen evolving complex, where oxygen is produced.
Location of the psa genes in the chloroplast genome of Arabidopsis thaliana.The 21 protein-coding genes involved in photosynthesis are displayed as green boxes. Photosystem I (PSI, or plastocyanin–ferredoxin oxidoreductase) is one of two photosystems in the photosynthetic light reactions of algae, plants, and cyanobacteria.