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Chloroplasts, containing thylakoids, visible in the cells of Rosulabryum 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.
Chloroplasts also need to balance the ratios of photosystem I and II for the electron transfer chain. The redox state of the electron carrier plastoquinone in the thylakoid membrane directly affects the transcription of chloroplast genes encoding proteins of the reaction centers of the photosystems, thus counteracting imbalances in the electron ...
Ultrastructure (or ultra-structure) is the architecture of cells and biomaterials that is visible at higher magnifications than found on a standard optical light microscope. This traditionally meant the resolution and magnification range of a conventional transmission electron microscope (TEM) when viewing biological specimens such as cells ...
Chloroplasts are diverse in morphology and include many forms, including, cup-shaped (e.g. Chlamydomonas), or axial, or parietal and reticulate (e.g. Oedogonium). [ 2 ] In many species, there may be one or more storage bodies called pyrenoids (central proteinaceous body covered with a starch sheath) that are localised around the chloroplast. [ 5 ]
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 ...
Lichtenthaler’s research fields are the photosynthesis of green plants, the light adaptation, pigment composition, photosynthetic function and ultrastructure of chloroplasts, the regulation of the plants’ isoprenoid biosynthesis, as well as the laser-induced fluorescence imaging of photosynthetic activity and of stress-detection in plants. [2]
The plastids differ both in their pigmentation and in their ultrastructure. For example, chloroplasts in plants and green algae have lost all phycobilisomes , the light harvesting complexes found in cyanobacteria, red algae and glaucophytes, but instead contain stroma and grana thylakoids .
Two families of reaction centers in photosystems can be distinguished: type I reaction centers (such as photosystem I in chloroplasts and in green-sulfur bacteria) and type II reaction centers (such as photosystem II in chloroplasts and in non-sulfur purple bacteria). The two photosystems originated from a common ancestor, but have since ...