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The liquid components of the cytoplasm of the eukaryotic and prokaryotic cells are referred to as the cytosol ( ancient Greek κύτος kýtos 'cell' and Latin solvere, solutum ' to solve', 'to dissolve'), also called cytosol .

The cytosol consists of about 70% water as well as the ions dissolved in it , small molecules and larger water-soluble molecules such as proteins. The protein content of the cytosol is 20–30%. Depending on the cell type, 25–50% of the total amount of protein is in the cytosol. Part of protein biosynthesis , translation , takes place in the cytosol . In addition, glycolysis , many steps in protein breakdown and many reactions of the intermediate metabolism of the cell take place here. This includes, for example, the synthesis and degradation of nucleotides or amino acids .

In eukaryotes, the cytosol is traversed by a network of thread-like structures (filaments) such as actin filaments , intermediate filaments or microtubules , which in their entirety form the cell skeleton ( cytoskeleton ).

Organization of a typical eukaryotic animal cell:
1. Nucleolus (nuclear body)
2. Cell nucleus (nucleus)
3. Ribosomes
4. Vesicle
5. Rough (granular) ER (ergastoplasm)
6. Golgi apparatus
7. Microtubules
8. Smooth (agranular) ER
9 . mitochondria
10. lysosome
11. cytoplasm (cytosol with a liquid phase)
12. peroxisomes
13. centrioles

In prokaryotes , the DNA is freely present in the cytosol, since these have no compartmentalization . Due to the dense accumulation of macromolecules in the cytosolic aqueous saline solution, the cytosol is referred to as a gel rather than an actual solution.

Cytosol with the most important solutes:
microtubules (light blue)
actin filaments (blue)
ribosomes (yellow and blue)
soluble proteins (light blue)
kinesin (red)
small molecules (white)
RNA (pink)

Individual evidence

  1. K. Luby-Phelps: Cytoarchitecture and physical properties of cytoplasm: volume, viscosity, diffusion, intracellular surface area. In: International review of cytology. Volume 192, 2000, pp. 189-221, doi : 10.1016 / S0074-7696 (08) 60527-6 , PMID 10553280 (review).