Cytosol+-+Plant

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====**Cytosol-** The fluid portion of a cell's cytoplasm, which lies outside the organelles and other insoluble components of the cytoplasm. Cytosol contains water, free proteins, and a variety of other substances; yet, far from being a complex biochemical broth, it is actually highly organized at the molecular level. Most importantly, it is where a major part of cellular metabolism takes place. The proteins within cytosol play an important role in glycolysis, serve as intracellular receptors, and form part of ribosomes, enabling protein synthesis. Cytosol also contains the cytoskeleton. http://www.daviddarling.info/encyclopedia/C/cytosol.html ====

==== The cytosol of a plant cell is The fluid portion of the cytoplasm, outside the organelles. Cytosol contains water, free proteins, and a variety of other substances; yet, far from being a complex biochemical broth, it is actually highly organized at the molecular level. Most importantly, it is where a major part of cellular metabolism takes place. The proteins within cytosol play an important role in glycolysis, serve as intracellular receptors, and form part of ribosomes, enabling protein synthesis. Cytosol also contains the cytoskeleton. In prokaryotes, all chemical reactions take place in the cytosol. In eukaryotes, the cytosol forms the surrounding environment of organelles. In plants, the amount of cytosol can be reduced due to the large tonoplast (central vacuole) that takes up most of the cell interior volume. ====
 * Cytosol : The cytosol is the "soup" within which all the other cell organelles reside and where most of the cellular metabolism occurs. Though mostly water, the cytosol is full of proteins that control cell metabolism including signal transduction pathways, glycolysis, intracellular receptors, and transcription factors. Cytoplasm is a collective term for the cytosol plus the organelles suspended within the cytosol.Cytosol**

The cytosol is the "soup" within which all the other cell organelles reside and where most of the cellular metabolism occurs. Though mostly water, the cytosol is full of proteins that control cell metabolism including signal transduction pathways, glycolysis, intracellular receptors, and transcription factors. Cytoplasm is a collective term for the cytosol plus the organelles suspended within the http://www.cellsalive.com/cells/membrane.htm The cytosol or **intracellular fluid** (or **cytoplasmic matrix**) is the liquid found inside cells. In eukaryotes this liquid is separated by cell membranes from the contents of the organelles suspended in the cytosol, such as the mitochondrial matrix inside the mitochondrion. The entire contents of a eukaryotic cell, minus the contents of the cell nucleus, are referred to as the cytoplasm. In prokaryotes, most of the chemical reactions of metabolism take place in the cytosol, while a few take place in membranes or in the periplasmic space. In eukaryotes, while many metabolic pathways still occur in the cytosol, others are contained within organelles. The cytosol is a complex mixture of substances dissolved in water. Although water forms the large majority of the cytosol, its structure and properties within cells is not well understood. The concentrations of ions such as sodium and potassium are different in the cytosol than in the extracellular fluid; these differences in ion levels are important in processes such as osmoregulation and cell signaling. The cytosol also contains large amounts of macromolecules, which can alter how molecules behave, through macromolecular crowding. Although once thought to be a simple solution of molecules, multiple levels of organization exist in the cytosol. These include concentration gradients of small molecules such as calcium, large complexes of enzymes that act together to carry out metabolic pathways, and protein complexes such as proteasomes and carboxysomes that enclose and separate parts of the cytosol. A cDNA library was constructed with mRNA isolated from heat-stressed cell cultures of Funaria hygrometrica (Bryophyta, Musci, Funariaceae). cDNA clones encoding six cytosolic small heat shock proteins (sHSPs) were identified using differential screening. Phylogenetic analysis of these sHSP sequences with other known sHSPs identified them as members of the previously described higher plant cytosolic class I and II families. Four of the F. hygrometrica sHSPs are members of the cytosolic class I family, and the other two are members of the cytosolic class II family. The presence of members of the cytosolic I and II sHSP families in a bryophyte indicates that these gene families are ancient, and evolved at least 450 MYA. This result also indicates that the plant sHSP gene families duplicated much earlier than did the well-studied phytochrome gene family. Members of the cytosolic I and II sHSP families are developmentally regulated in seeds and flowers in higher plants. Our findings show that the two cytosolic sHSP families evolved before the appearance of these specialized structures. Previous analysis of angiosperm sHSPs had identified class- or family-specific amino acid consensus regions and determined that rate heterogeneity exists among the different sHSP families. The analysis of the F. hygrometrica sHSP sequences reveals patterns and rates of evolution distinct from those seen among angiosperm sHSPs. Some, but not all, of the amino acid consensus regions identified in seed plants are conserved in the F. hygrometrica sHSPs. Taken together, the results of this study illuminate the evolution of the sHSP gene families and illustrate the importance of including representatives of basal land plant lineages in plant molecular evolutionary studies.


 * Cytosol**: liquid part of the cytoplasm.



Cytosol : The cytosol is the "soup" within which all the other cell organelles reside and where most of the cellular metabolism occurs. Though mostly water, the cytosol is full of proteins that control cell metabolism including signal transduction pathways, glycolysis, intracellular receptors, and transcription factors. Cytoplasm is a collective term for the cytosol plus the organelles suspended within the cytosol. http://www.cellsalive.com/cells/membrane.htm



The cytosol is a complex mixture of substances dissolved in water. Although water forms the large majority of the cytosol, its structure and properties within cells is not well understood. The concentrations of ions such as sodium and potassium are different in the cytosol than in the extracellular fluid; these differences in ion levels are important in processes such as osmoregulation and cell signaling. The cytosol also contains large amounts of macromolecules, which can alter how molecules behave, through macromolecular crowding. Although once thought to be a simple solution of molecules, multiple levels of organization exist in the cytosol. These include concentration gradients of small molecules such as calcium, large complexes of enzymes that act together to carry out metabolic pathways, and protein complexes such as proteasomes and carboxysomes that enclose and separate parts of the cytosol. In the early 20th century the sum total of the contents of the cell (the //protoplasm//) were commonly classified into the contents of the nucleus (the //nucleoplasm//) and the remainder of the cell contents, the //cytoplasm.// The cytoplasm was further classified into solid structures, such as organelles and the cytoskeleton, and a liquid component that was variously called the cell sap, enchylema, hyaloplasm, paramitone, interfilar substance, or ground substance. The term //cytosol// was first introduced in 1965 by H.A. Lardy, and initially referred to the liquid that was produced by breaking cells apart and pelleting all the insoluble components by ultracentrifugation. Such a soluble cell extract is not identical to the soluble part of the cell cytoplasm and is usually called a //cytoplasmic fraction//. The term //cytosol// is now used to refer to the liquid phase of the cytoplasm in an intact cell, this excludes any part of the cytoplasm that is contained within organelles. Due to the possibility of confusion between the use of the word //cytosol// to refer to both extracts of cells and the soluble part of the cytoplasm in intact cells, the phrase //aqueous cytoplasm// has been used to describe the liquid contents of the cytoplasm of living cells.[|[][|3]] The proportion of cell volume that is cytosol varies: for example while this compartment forms the bulk of cell structure in bacteria, in plant cells the main compartment is the large central vacule  The cytosol consists mostly of water, dissolved ions, small molecules, and large water-soluble molecules (such as proteins). The majority of these non-protein molecules have a molecular molecule  of less than 300 DA   .This mixture of small molecules is extraordinarily complex, as the variety of molecules that are involved in metabolism (the metabolis   ) is immense. For example up to 200,000 different small molecules might be made in plants, although not all these will be present in the same species, or in a single cell. Indeed, estimates of the number of metabolites in single cells such as //E. coli// and bakers yeast  predict that under 1,000 are made.[|[10]][|[11][|]] Most of the cytosol is water, which makes up about 70% of a typical cell by volume.Normal human cytosolic pH ranges between 7.3 - 7.5, depending on the cell type involved, whereas the pH of the extracellular fluid is 7.4.The viscosity of cytoplasm is roughly the same as pure water, although diffusion of small molecules through this liquid is about four-fold slower than in pure water, due mostly to collisions with the large numbers of macromolecules in the cytosol. Studies in the brine shrimp have studied how water affects cell functions; these found that reducing the amount of water in a cell below 80% of the normal level inhibits metabolism, with this decreasing progressively as the cell dries out and all metabolism halting at a water level about 30% of normal. Although water is known to be vital for life, the structure of this water in the cytosol is not well understood. This is mostly due to the fact that methods such as nuclear magnetic resonance only give information on the average structure of water, and cannot measure local variations at the microscopic scale. Even the structure of pure water is poorly-understood, due to the ability of water to form structures such as water clusters through hydrogen bonds.The classic view of water in cells is that about 5% of this water is strongly bound in by solutes or macromolecules as water of solvation, while the majority has the same structure as pure water. This water of solvation is not active in osmosis and may have different solvent properties, so that some dissolved molecules are excluded, while others become concentrate. However, others argue that the effects of the high concentrations of macromolecules in cells extend throughout the cytosol and that water in cells behaves very differently from the water in dilute solutions. These ideas include the proposal that cells contain zones of low and high-density water, which could have widespread effects on the structures and functions of the other parts of the cell.