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During the development/ differentiation of proplastids to chloroplasts—and when plastids are differentiating from one type to another—nucleoids change in morphology, size, and location within the organelle. The remodelling of plastid nucleoids is believed to occur by modifications to the abundance of and the composition of nucleoid proteins.
Chloroplasts probably evolved following an endosymbiotic event between an ancestral, photosynthetic cyanobacterium and an early eukaryotic phagotroph. [17] This event (termed primary endosymbiosis) is at the origin of the red and green algae (including the land plants or Embryophytes which emerged within them) and the glaucophytes, which together make up the oldest evolutionary lineages of ...
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. Chloroplasts have a high concentration of chlorophyll pigments which capture the energy from sunlight and convert it to chemical energy and release oxygen.
Photosystem I [1] is an integral membrane protein complex that uses light energy to catalyze the transfer of electrons across the thylakoid membrane from plastocyanin to ferredoxin. Ultimately, the electrons that are transferred by Photosystem I are used to produce the moderate-energy hydrogen carrier NADPH . [ 2 ]
[1] 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 ...
Euglena chloroplasts contain pyrenoids, used in the synthesis of paramylon, a form of starch energy storage enabling Euglena to survive periods of light deprivation. The presence of pyrenoids is used as an identifying feature of the genus, separating it from other euglenoids, such as Lepocinclis and Phacus .
Along with red algae [1] and cyanobacteria, they harvest light via phycobilisomes, structures consisting largely of phycobiliproteins. The green algae and land plants have lost that pigment. [ 11 ] Like red algae, and in contrast to green algae and plants, glaucophytes store fixed carbon in the cytosol .
The ochrophytes are mostly photosynthetic. As such, they may possess one or more photosynthetic plastids (chloroplasts) per cell. [14] Some groups contain species with leucoplasts, chloroplasts that have lost photosynthetic capacity and pigments but presumably continue to play a role in the synthesis of amino acids, lipids and heme groups. [10]