Endocytosis

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Endoctosis is a vesicular method of transport in which a cell can ingest molecules from the plasma membrane. This method of transport is widely used throughout all of the bodies cells as it allows the uptake of both macromolecules and particulate substances. Endocyosis begins with the material to be ingested being confined by the plasma membrane, once confined it buds off forming an endocytic vesicle which can then be released in to the cell to carry out its function.
A special type of endocytosis is Phagocytosis, this mechanism involves the ingestion and consumption of large particles, these can include dead cells and microorganims. This type of endocytosis is uses large vesicles, known as phagosomes. These phagosomes are genreally larger than 250 nm in diameter. It should be noted that Phagocytosis is not only used for nutrition, it is used as a defence mechanism against infection by ingesting invading microorganisms.
Another method of endocytosis is pinocytosis. This uses much smaller vesicles than Phagocytosis, around 100 nm in diameter. These vesicles are called pinocytic vesicles and are used in the ingestion of fluid and solute into the cell. Pinocytosis is more frequently used in eukaryotic cells, however it is more efficient for the uptake of large molecules to use specialised phagocytic cells.

The opposite of Endocytosis is Exocytosis [1].

References

  1. Alberts, B et al. (2008). Molecular Biology of the Cell. 5th ed. US: Garland Science. 1268 (Page 746)
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