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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.
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. The glaucocystophycean plastid—in contrast to chloroplasts and rhodoplasts—is still surrounded by the remains of the ...
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 ...
In plants and algae, photosynthesis takes place in organelles called chloroplasts. A typical plant cell contains about 10 to 100 chloroplasts. The chloroplast is enclosed by a membrane. This membrane is composed of a phospholipid inner membrane, a phospholipid outer membrane, and an intermembrane space.
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 ...
The chloroplast is derived from a cyanobacterial primary endosymbiosis that began over one billion years ago. An oxygenic, photosynthetic free-living cyanobacterium was engulfed and kept by a heterotrophic protist and eventually evolved into the present intracellular organelle.
A digestive tubule cell of the sea slug Elysia clarki, packed with chloroplasts taken from green algae. C = chloroplast, N = cell nucleus. Electron micrograph: scale bar is 3 μm. Kleptoplasty or kleptoplastidy is a process in symbiotic relationships whereby plastids, notably chloroplasts from algae, are sequestered by the host
Ochrophyte chloroplasts contain chlorophylls a and c as photosynthetic pigments, in addition to fucoxanthin. [13] Chlorophyll a binds to thylakoids, while the c pigment is present in the stroma. [10] The most frequent accessory pigment in ochrophytes is the yellow β-carotene.