Cytosol
The cytosol is the internal fluid of the cell, and a portion of
cell metabolism occurs here.
Proteins within the cytosol play an important role in signal transduction pathways and
glycolysis. They also act as intracellular receptors and form part of the
ribosomes, enabling protein synthesis.
In prokaryotes, all chemical reactions take place in the cytosol. In
eukaryotes, the cytosol contains the cell
organelles; this is collectively called cytoplasm. In plants, the amount of cytosol can be reduced due to the large
tonoplast that takes up most of the cell interior volume.
Encyclopedia
The
cytosol is the internal fluid of the cell, and a portion of
cell metabolism occurs here.
Proteins within the cytosol play an important role in signal transduction pathways and
glycolysis. They also act as intracellular receptors and form part of the
ribosomes, enabling protein synthesis.
In prokaryotes, all chemical reactions take place in the cytosol. In
eukaryotes, the cytosol contains the cell
organelles; this is collectively called cytoplasm. In plants, the amount of cytosol can be reduced due to the large
tonoplast that takes up most of the cell interior volume.
The cytosol also surrounds the
cytoskeleton, which is made of fibrous proteins . In many organisms, the cytoskeleton maintains the shape of the cell, anchors organelles, and controls internal movement of structures .
The cytosol is not a "soup" with free-floating particles, but is highly organized on the molecular level. As the concentration of soluble molecules increases within the cytosol, an osmotic gradient builds up toward the outside of the cell. Water flows into the cell, making the cell larger. To prevent the cell from bursting apart, molecular pumps in the
plasma membrane, the cytoskeleton, the tonoplast or the
cell wall , are used to counteract the osmotic pressure.
Details
Cytosol mostly consists of water, dissolved ions, small molecules, and large water-soluble molecules . It contains about 20% to 30%
protein.
Normal human cytosolic
pH is 7.0 , whereas the
pH of the extracellular fluid is 7.4.
References
Life: The Science of Biology. Purves, Sadava, Orians, Heller. Sunderland, MA. Sinauer Associates, Inc. 2004. ISBN 0-7167-9856-5
