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{{Short description|All of the contents of a eukaryotic cell except the nucleus |
{{Short description|All of the contents of a eukaryotic cell except the nucleus}} |
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{{Use dmy dates|date=July 2020}} |
{{Use dmy dates|date=July 2020}} |
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{{Organelle diagram}} |
{{Organelle diagram}} |
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⚫ | In [[cell biology]], the '''cytoplasm''' describes all material within a [[eukaryote|eukaryotic]] [[Cell (biology)|cell]], enclosed by the [[cell membrane]], except for the [[cell nucleus]]. The material inside the nucleus and contained within the [[nuclear envelope|nuclear membrane]] is termed the [[nucleoplasm]]. The main components of the cytoplasm are the [[cytosol]] (a gel-like substance), the [[organelle]]s (the cell's internal sub-structures), and various [[cytoplasmic inclusion]]s. The cytoplasm is about 80% water and is usually colorless.<ref>{{cite book | vauthors = Shepherd VA | title = The cytomatrix as a cooperative system of macromolecular and water networks | volume = 75 | pages = 171–223 | date = 2006 | pmid = 16984813 | doi = 10.1016/S0070-2153(06)75006-2 | isbn = 9780121531751 | series = Current Topics in Developmental Biology }}</ref> |
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In [[cell biology]], the '''cytoplakak |
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The submicroscopic ground cell substance or cytoplasmic matrix |
The submicroscopic ground cell substance, or cytoplasmic matrix, that remains after the exclusion of the cell [[organelle]]s and particles is [[groundplasm]]. It is the [[hyaloplasm]] of light microscopy, a highly complex, polyphasic system in which all resolvable cytoplasmic elements are suspended, including the larger organelles such as the [[ribosome]]s, [[mitochondria]], plant [[plastid]]s, [[lipid]] droplets, and [[vacuole]]s. |
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Many cellular activities take place within the cytoplasm, such as many [[metabolic pathway]]s, including [[glycolysis]], [[photosynthesis]], and processes such as [[cell division]]. The concentrated inner area is called the [[endoplasm]] and the outer layer is called the [[cell cortex]], or [[ectoplasm (cell biology)|ectoplasm]]. |
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Movement of [[calcium ion]]s in and out of the cytoplasm is a [[Recognition signal|signaling]] activity for [[metabolic]] processes.<ref>{{cite book | last = Hogan | first = C. Michael | date = 2010 | chapter-url = http://www.eoearth.org/article/Calcium?topic=49557 | chapter = Calcium | archive-url = https://web.archive.org/web/20120612123626/http://www.eoearth.org/article/Calcium?topic=49557 | archive-date=12 June 2012 | title = Encyclopedia of Earth | veditors = Jorgensen A, Cleveland C | publisher = National Council for Science and the Environment }}</ref> |
Movement of [[calcium ion]]s in and out of the cytoplasm is a [[Recognition signal|signaling]] activity for [[metabolic]] processes.<ref>{{cite book | last = Hogan | first = C. Michael | date = 2010 | chapter-url = http://www.eoearth.org/article/Calcium?topic=49557 | chapter = Calcium | archive-url = https://web.archive.org/web/20120612123626/http://www.eoearth.org/article/Calcium?topic=49557 | archive-date=12 June 2012 | title = Encyclopedia of Earth | veditors = Jorgensen A, Cleveland C | publisher = National Council for Science and the Environment }}</ref> |
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==Physical nature== |
==Physical nature== |
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It remains uncertain how the various components of the cytoplasm interact to allow movement of [[organelle]]s while maintaining the cell's structure. The flow of cytoplasmic components plays an important role in many cellular functions which are dependent on the [[Semipermeable membrane|permeability]] of the cytoplasm.<ref>{{cite book |chapter=Spatial Modeling of Cell Signaling Networks |pmc=3519356 |pmid=22482950 |doi=10.1016/B978-0-12-388403-9.00008-4 |volume=110 |year=2012 |pages=195–221 |vauthors=Cowan AE, Moraru II, Schaff JC, Slepchenko BM, Loew LM |
It remains uncertain how the various components of the cytoplasm interact to allow movement of [[organelle]]s while maintaining the cell's structure. The flow of cytoplasmic components plays an important role in many cellular functions which are dependent on the [[Semipermeable membrane|permeability]] of the cytoplasm.<ref>{{cite book |chapter=Spatial Modeling of Cell Signaling Networks |pmc=3519356 |pmid=22482950 |doi=10.1016/B978-0-12-388403-9.00008-4 |volume=110 |year=2012 |pages=195–221 |vauthors=Cowan AE, Moraru II, Schaff JC, Slepchenko BM, Loew LM |isbn=9780123884039 |title=Computational Methods in Cell Biology}}</ref> An example of such function is [[cell signalling]], a process which is dependent on the manner in which signaling molecules are allowed to [[diffuse]] across the cell.<ref>{{cite journal | vauthors = Holcman D, Korenbrot JI | title = Longitudinal diffusion in retinal rod and cone outer segment cytoplasm: the consequence of cell structure | journal = Biophysical Journal | volume = 86 | issue = 4 | pages = 2566–82 | date = April 2004 | pmid = 15041693 | pmc = 1304104 | doi = 10.1016/S0006-3495(04)74312-X | bibcode = 2004BpJ....86.2566H }}</ref> While small signaling molecules like [[calcium ions]] are able to diffuse with ease, larger molecules and subcellular structures often require aid in moving through the cytoplasm.<ref name="autogenerated1">{{cite journal | vauthors = Parry BR, Surovtsev IV, Cabeen MT, O'Hern CS, Dufresne ER, Jacobs-Wagner C | title = The bacterial cytoplasm has glass-like properties and is fluidized by metabolic activity | journal = Cell | volume = 156 | issue = 1–2 | pages = 183–94 | date = January 2014 | pmid = 24361104 | pmc = 3956598 | doi = 10.1016/j.cell.2013.11.028 | bibcode = 2014APS..MARJ16002P }}</ref> The irregular dynamics of such particles have given rise to various theories on the nature of the cytoplasm. |
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===As a sol-gel=== |
===As a sol-gel=== |
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There has long been evidence that the cytoplasm behaves like a [[sol-gel]].<ref>{{cite journal|title=The contractile vacuole in Euplotes: An example of the sol-gel reversibility of cytoplasm| doi=10.1002/jez.1400370302 |volume=37 |issue=3 |journal=Journal of Experimental Zoology |pages=259–289 |year=1923 |vauthors=Taylor CV}}</ref> It is thought that the component molecules and structures of the cytoplasm behave at times like a disordered [[colloidal]] solution (sol) and at other times like an integrated network, forming a solid mass (gel). This theory thus proposes that the cytoplasm exists in distinct fluid and solid phases depending on the level of interaction between cytoplasmic components, which may explain the differential dynamics of different particles observed moving through the cytoplasm. A papers suggested that at [[length scale]] smaller than 100 [[nanometer|nm]], the cytoplasm acts like a liquid, while in a larger length scale, it acts like a gel.<ref>{{cite journal |last1=Kwapiszewska |first1=Karina |last2=Szczepański |first2=Krzysztof |title=Nanoscale Viscosity of Cytoplasm Is Conserved in Human Cell Lines |journal=[[The Journal of Physical Chemistry Letters]] |date=31 July 2020 |volume=11 |issue=16 |pages=6914–6920 |doi=10.1021/acs.jpclett.0c01748 |pmid=32787203 |pmc=7450658 |display-authors=1|doi-access=free }}</ref> |
There has long been evidence that the cytoplasm behaves like a [[sol-gel]].<ref>{{cite journal|title=The contractile vacuole in Euplotes: An example of the sol-gel reversibility of cytoplasm| doi=10.1002/jez.1400370302 |volume=37 |issue=3 |journal=Journal of Experimental Zoology |pages=259–289 |year=1923 |vauthors=Taylor CV| bibcode=1923JEZ....37..259T }}</ref> It is thought that the component molecules and structures of the cytoplasm behave at times like a disordered [[colloidal]] solution (sol) and at other times like an integrated network, forming a solid mass (gel). This theory thus proposes that the cytoplasm exists in distinct fluid and solid phases depending on the level of interaction between cytoplasmic components, which may explain the differential dynamics of different particles observed moving through the cytoplasm. A papers suggested that at [[length scale]] smaller than 100 [[nanometer|nm]], the cytoplasm acts like a liquid, while in a larger length scale, it acts like a gel.<ref>{{cite journal |last1=Kwapiszewska |first1=Karina |last2=Szczepański |first2=Krzysztof |title=Nanoscale Viscosity of Cytoplasm Is Conserved in Human Cell Lines |journal=[[The Journal of Physical Chemistry Letters]] |date=31 July 2020 |volume=11 |issue=16 |pages=6914–6920 |doi=10.1021/acs.jpclett.0c01748 |pmid=32787203 |pmc=7450658 |display-authors=1|doi-access=free }}</ref> |
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===As a glass=== |
===As a glass=== |
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It has been proposed that the cytoplasm behaves like a [[glass]]-forming liquid approaching the [[glass transition]].<ref name="autogenerated1"/> In this theory, the greater the concentration of cytoplasmic components, the less the cytoplasm behaves like a liquid and the more it behaves as a solid glass, freezing more significant cytoplasmic components in place (it is thought that the cell's metabolic activity can fluidize the cytoplasm to allow the movement of such more significant cytoplasmic components).<ref name="autogenerated1"/> A cell's ability to vitrify in the absence of metabolic activity, as in dormant periods, may be beneficial as a defense strategy. A solid glass cytoplasm would freeze subcellular structures in place, preventing damage, while allowing the transmission of tiny proteins and metabolites, helping to kickstart growth upon the cell's revival from [[dormancy]].<ref name="autogenerated1"/> |
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===Other perspectives=== |
===Other perspectives=== |
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{{main|Cytosol}} |
{{main|Cytosol}} |
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The cytosol is the portion of the cytoplasm not contained within membrane-bound organelles. Cytosol makes up about 70% of the cell volume and is a complex mixture of [[cytoskeleton]] filaments, dissolved molecules, and water. The cytosol's filaments include the [[protein filament]]s such as [[actin filament]]s and [[microtubule]]s that make up the cytoskeleton, as well as soluble [[protein]]s and small structures such as [[ribosome]]s, [[proteasome]]s, and the mysterious [[Vault (organelle)|vault complexes]].<ref>{{cite journal | vauthors = van Zon A, Mossink MH, Scheper RJ, Sonneveld P, Wiemer EA | s2cid = 21196262 | title = The vault complex | journal = Cellular and Molecular Life Sciences | volume = 60 | issue = 9 | pages = 1828–37 | date = September 2003 | pmid = 14523546 | doi = 10.1007/s00018-003-3030-y }}</ref> The inner, granular and more fluid portion of the cytoplasm is referred to as endoplasm.[[File:Localisations02eng.jpg|thumb|right|250px|Proteins in different [[cellular compartment]]s and structures [[Protein tag#Protein tags|tagged]] with [[green fluorescent protein]]]] |
The cytosol is the portion of the cytoplasm not contained within membrane-bound organelles. Cytosol makes up about 70% of the cell volume and is a complex mixture of [[cytoskeleton]] filaments, dissolved molecules, and water. The cytosol's filaments include the [[protein filament]]s such as [[actin filament]]s and [[microtubule]]s that make up the cytoskeleton, as well as soluble [[protein]]s and small structures such as [[ribosome]]s, [[proteasome]]s, and the mysterious [[Vault (organelle)|vault complexes]].<ref>{{cite journal | vauthors = van Zon A, Mossink MH, Scheper RJ, Sonneveld P, Wiemer EA | s2cid = 21196262 | title = The vault complex | journal = Cellular and Molecular Life Sciences | volume = 60 | issue = 9 | pages = 1828–37 | date = September 2003 | pmid = 14523546 | doi = 10.1007/s00018-003-3030-y | pmc = 11138885 }}</ref> The inner, granular and more fluid portion of the cytoplasm is referred to as endoplasm.[[File:Localisations02eng.jpg|thumb|right|250px|Proteins in different [[cellular compartment]]s and structures [[Protein tag#Protein tags|tagged]] with [[green fluorescent protein]]]] |
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Due to this network of fibres and high concentrations of dissolved [[macromolecule]]s, such as [[protein]]s, an effect called [[macromolecular crowding]] occurs and the cytosol does not act as an [[ideal solution]]. This crowding effect alters how the components of the cytosol interact with each other. |
Due to this network of fibres and high concentrations of dissolved [[macromolecule]]s, such as [[protein]]s, an effect called [[macromolecular crowding]] occurs and the cytosol does not act as an [[ideal solution]]. This crowding effect alters how the components of the cytosol interact with each other. |
Cell biology | |
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Animal cell diagram | |
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Incell biology, the cytoplasm describes all material within a eukaryotic cell, enclosed by the cell membrane, except for the cell nucleus. The material inside the nucleus and contained within the nuclear membrane is termed the nucleoplasm. The main components of the cytoplasm are the cytosol (a gel-like substance), the organelles (the cell's internal sub-structures), and various cytoplasmic inclusions. The cytoplasm is about 80% water and is usually colorless.[1]
The submicroscopic ground cell substance, or cytoplasmic matrix, that remains after the exclusion of the cell organelles and particles is groundplasm. It is the hyaloplasm of light microscopy, a highly complex, polyphasic system in which all resolvable cytoplasmic elements are suspended, including the larger organelles such as the ribosomes, mitochondria, plant plastids, lipid droplets, and vacuoles.
Many cellular activities take place within the cytoplasm, such as many metabolic pathways, including glycolysis, photosynthesis, and processes such as cell division. The concentrated inner area is called the endoplasm and the outer layer is called the cell cortex, or ectoplasm.
Movement of calcium ions in and out of the cytoplasm is a signaling activity for metabolic processes.[2]
Inplants, movement of the cytoplasm around vacuoles is known as cytoplasmic streaming.
The term was introduced by Rudolf von Kölliker in 1863, originally as a synonym for protoplasm, but later it has come to mean the cell substance and organelles outside the nucleus.[3][4]
There has been certain disagreement on the definition of cytoplasm, as some authors prefer to exclude from it some organelles, especially the vacuoles[5] and sometimes the plastids.[6]
It remains uncertain how the various components of the cytoplasm interact to allow movement of organelles while maintaining the cell's structure. The flow of cytoplasmic components plays an important role in many cellular functions which are dependent on the permeability of the cytoplasm.[7] An example of such function is cell signalling, a process which is dependent on the manner in which signaling molecules are allowed to diffuse across the cell.[8] While small signaling molecules like calcium ions are able to diffuse with ease, larger molecules and subcellular structures often require aid in moving through the cytoplasm.[9] The irregular dynamics of such particles have given rise to various theories on the nature of the cytoplasm.
There has long been evidence that the cytoplasm behaves like a sol-gel.[10] It is thought that the component molecules and structures of the cytoplasm behave at times like a disordered colloidal solution (sol) and at other times like an integrated network, forming a solid mass (gel). This theory thus proposes that the cytoplasm exists in distinct fluid and solid phases depending on the level of interaction between cytoplasmic components, which may explain the differential dynamics of different particles observed moving through the cytoplasm. A papers suggested that at length scale smaller than 100 nm, the cytoplasm acts like a liquid, while in a larger length scale, it acts like a gel.[11]
It has been proposed that the cytoplasm behaves like a glass-forming liquid approaching the glass transition.[9] In this theory, the greater the concentration of cytoplasmic components, the less the cytoplasm behaves like a liquid and the more it behaves as a solid glass, freezing more significant cytoplasmic components in place (it is thought that the cell's metabolic activity can fluidize the cytoplasm to allow the movement of such more significant cytoplasmic components).[9] A cell's ability to vitrify in the absence of metabolic activity, as in dormant periods, may be beneficial as a defense strategy. A solid glass cytoplasm would freeze subcellular structures in place, preventing damage, while allowing the transmission of tiny proteins and metabolites, helping to kickstart growth upon the cell's revival from dormancy.[9]
Research has examined the motion of cytoplasmic particles independent of the nature of the cytoplasm. In such an alternative approach, the aggregate random forces within the cell caused by motor proteins explain the non-Brownian motion of cytoplasmic constituents.[12]
The three major elements of the cytoplasm are the cytosol, organelles and inclusions.
The cytosol is the portion of the cytoplasm not contained within membrane-bound organelles. Cytosol makes up about 70% of the cell volume and is a complex mixture of cytoskeleton filaments, dissolved molecules, and water. The cytosol's filaments include the protein filaments such as actin filaments and microtubules that make up the cytoskeleton, as well as soluble proteins and small structures such as ribosomes, proteasomes, and the mysterious vault complexes.[13] The inner, granular and more fluid portion of the cytoplasm is referred to as endoplasm.
Due to this network of fibres and high concentrations of dissolved macromolecules, such as proteins, an effect called macromolecular crowding occurs and the cytosol does not act as an ideal solution. This crowding effect alters how the components of the cytosol interact with each other.
Organelles (literally "little organs") are usually membrane-bound structures inside the cell that have specific functions. Some major organelles that are suspended in the cytosol are the mitochondria, the endoplasmic reticulum, the Golgi apparatus, vacuoles, lysosomes, and in plant cells, chloroplasts.
The inclusions are small particles of insoluble substances suspended in the cytosol. A huge range of inclusions exist in different cell types, and range from crystals of calcium oxalateorsilicon dioxide in plants,[14][15] to granules of energy-storage materials such as starch,[16] glycogen,[17]orpolyhydroxybutyrate.[18] A particularly widespread example are lipid droplets, which are spherical droplets composed of lipids and proteins that are used in both prokaryotes and eukaryotes as a way of storing lipids such as fatty acids and sterols.[19] Lipid droplets make up much of the volume of adipocytes, which are specialized lipid-storage cells, but they are also found in a range of other cell types.
The cytoplasm, mitochondria, and most organelles are contributions to the cell from the maternal gamete. Contrary to the older information that disregards any notion of the cytoplasm being active, new research has shown it to be in control of movement and flow of nutrients in and out of the cell by viscoplastic behavior and a measure of the reciprocal rate of bond breakage within the cytoplasmic network.[20]
The material properties of the cytoplasm remain an ongoing investigation. A method of determining the mechanical behaviour of living cell mammalian cytoplasm with the aid of optical tweezers has been described.[21]
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Structures of the cell / organelles
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Endomembrane system |
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Cytoskeleton |
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Endosymbionts |
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