Cytoplasm
Animal cell diagram | |
|---|---|
 Components of a typical animal cell:
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In
The submicroscopic ground cell substance, or cytoplasmic matrix, that remains after the exclusion of the cell
.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
In plants, movement of the cytoplasm around vacuoles is known as cytoplasmic streaming.
History
The term was introduced by
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]
Physical nature
It remains uncertain how the various components of the cytoplasm interact to allow movement of
As a sol-gel
There has long been evidence that the cytoplasm behaves like a
As a glass
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]
Other perspectives
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
Constituents
The three major elements of the cytoplasm are the
Cytosol
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
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
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
Cytoplasmic inclusions
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 oxalate or silicon dioxide in plants,[14][15] to granules of energy-storage materials such as starch,[16] glycogen,[17] or polyhydroxybutyrate.[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.
Controversy and research
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]
See also
- Amoeboid movement – Mode of locomotion in eukaryotic cells
- Cytoplasmic streaming – Flow of the cytoplasm inside the cell
- Protoplasm – Alternative term for cytoplasm or cytoplasm and nucleoplasm
- Syncytium – Type of multinucleate cell
References
- PMID 16984813.
- ^ Hogan CM (2010). "Calcium". In Jorgensen A, Cleveland C (eds.). Encyclopedia of Earth. National Council for Science and the Environment. Archived from the original on 12 June 2012.
- ^ von Kölliker R (1863). "4. Auflage". Handbuch der Gewebelehre des Menschen. Leipzig: Wilhelm Engelmann.
- ISBN 9781400853410.)
{{cite book}}: CS1 maint: location missing publisher (link - ISBN 9780323153010.
- from the original on 27 August 2017.
- PMID 22482950.
- PMID 15041693.
- ^ PMID 24361104.
- .
- PMID 32787203.
- PMID 25126787.
- S2CID 21196262.
- .
- S2CID 24520433.
- PMID 14502990.
- PMID 12179957.
- PMID 2087222.
- PMID 11470496.
- S2CID 9782043.
- PMID 28827333.
External links
- Luby-Phelps K (2000). "Cytoarchitecture and physical properties of cytoplasm: volume, viscosity, diffusion, intracellular surface area". Microcompartmentation and Phase Separation in Cytoplasm (PDF). International Review of Cytology. Vol. 192. pp. 189–221. PMID 10553280. Archived from the original (PDF) on 11 September 2008.)
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