Editing Vacuole (section)

== Function ==
The function and significance of vacuoles varies greatly according to the type of cell in which they are present, having much greater prominence in the cells of plants, fungi and certain protists than those of animals and bacteria. In general, the functions of the vacuole include:

* Isolating materials that might be harmful or a threat to the cell
* Containing waste products
* Containing water in plant cells
* Maintaining internal [[hydrostatic pressure]] or [[turgor]] within the cell
* Maintaining an [[acid]]ic internal [[pH]]
* Containing small molecules
* Exporting unwanted substances from the cell
* Allowing plants to support structures such as leaves and flowers due to the pressure of the central vacuole
* By increasing in size, allowing the germinating plant or its organs (such as leaves) to grow very quickly and through using up mostly just water.<ref name="pmid190429152">{{cite journal|vauthors=Okubo-Kurihara E, Sano T, Higaki T, Kutsuna N, Hasezawa S|date=January 2009|title=Acceleration of vacuolar regeneration and cell growth by overexpression of an aquaporin NtTIP1;1 in tobacco BY-2 cells|journal=Plant & Cell Physiology|volume=50|issue=1|pages=151–60|doi=10.1093/pcp/pcn181|pmid=19042915|doi-access=free}}</ref>
* In seeds, storing proteins needed for germination (these are kept in 'protein bodies', which are modified vacuoles).<ref>{{cite book|last=Matile|first=Phillipe|title=Discoveries in Plant Biology|date=1993|publisher=World Scientific Publishing Co Pte Ltd|volume=1|chapter=Chapter 18: Vacuoles, discovery of lysosomal origin|name-list-style=vanc}}</ref>

Vacuoles also play a major role in [[autophagy]], maintaining a balance between [[biogenesis]] (production) and degradation (or turnover), of many substances and cell structures in certain organisms. They also aid in the [[lysis]] and recycling of misfolded proteins that have begun to build up within the cell. Thomas Boller<ref>[http://plantbiology.unibas.ch/people/boller/boller.htm Thomas Boller] {{Webarchive|url=https://web.archive.org/web/20131206010355/http://plantbiology.unibas.ch/people/boller/boller.htm|date=2013-12-06}}. Plantbiology.unibas.ch. Retrieved on 2011-09-02.</ref> and others proposed that the vacuole participates in the destruction of invading [[bacteria]] and [[Robert B. Mellor]] proposed organ-specific forms have a role in 'housing' symbiotic bacteria. In protists,{{efn|For example the [[Food vacuole|food vacuole in ''Plasmodium'']].}} vacuoles have the additional function of storing food which has been absorbed by the organism and assisting in the digestive and waste management process for the cell.<ref>{{cite journal|vauthors=Jezbera J, Hornák K, Simek K|date=May 2005|title=Food selection by bacterivorous protists: insight from the analysis of the food vacuole content by means of fluorescence in situ hybridization|journal=FEMS Microbiology Ecology|volume=52|issue=3|pages=351–63|doi=10.1016/j.femsec.2004.12.001|pmid=16329920|doi-access=free}}</ref>

In animal cells, vacuoles perform mostly subordinate roles, assisting in larger processes of [[exocytosis]] and [[endocytosis]].

Animal vacuoles are smaller than their plant counterparts but also usually greater in number.<ref name="Becker2">{{cite book|author=Becker B|url=https://archive.org/details/internationalrev0000unse_w6f2/page/1|title=Function and evolution of the vacuolar compartment in green algae and land plants (Viridiplantae)|year=2007|isbn=9780123742636|series=International Review of Cytology|volume=264|pages=[https://archive.org/details/internationalrev0000unse_w6f2/page/1 1–24]|doi=10.1016/S0074-7696(07)64001-7|pmid=17964920}}</ref> There are also animal cells that do not have any vacuoles.<ref>[http://www.biology-online.org/11/1_plant_cells_vs_animal_cells.htm Plant cells vs. Animal cells] {{Webarchive|url=https://web.archive.org/web/20190201065519/https://www.biology-online.org/11/1_plant_cells_vs_animal_cells.htm|date=2019-02-01}}. Biology-Online.org</ref>

Exocytosis is the extrusion process of proteins and lipids from the cell. These materials are absorbed into secretory granules within the [[Golgi apparatus]] before being transported to the cell membrane and secreted into the extracellular environment. In this capacity, vacuoles are simply storage vesicles which allow for the containment, transport and disposal of selected proteins and lipids to the extracellular environment of the cell.

Endocytosis is the reverse of exocytosis and can occur in a variety of forms. [[Phagocytosis]] ("cell eating") is the process by which bacteria, dead tissue, or other bits of material visible under the microscope are engulfed by cells. The material makes contact with the cell membrane, which then invaginates. The [[invagination]] is pinched off, leaving the engulfed material in the membrane-enclosed vacuole and the cell membrane intact. [[Pinocytosis]] ("cell drinking") is essentially the same process, the difference being that the substances ingested are in solution and not visible under the microscope.<ref name="Ganong20032">{{cite book|author=William F. Ganong, MD|title=Review of medical physiology|year=2003|edition=21st}}</ref> Phagocytosis and pinocytosis are both undertaken in association with [[lysosomes]] which complete the breakdown of the material which has been engulfed.<ref>{{cite book|author=Reggiori F|title=Current Topics in Developmental Biology Volume 74|year=2006|isbn=9780121531744|volume=74|pages=1–30|chapter=Membrane Origin for Autophagy|doi=10.1016/S0070-2153(06)74001-7|pmc=7112310|pmid=16860663}}</ref>

''[[Salmonella]]'' is able to survive and reproduce in the vacuoles of several [[mammal]] species after being engulfed.<ref>{{cite journal|vauthors=Knodler LA, Steele-Mortimer O|date=September 2003|title=Taking possession: biogenesis of the Salmonella-containing vacuole|journal=Traffic|volume=4|issue=9|pages=587–99|doi=10.1034/j.1600-0854.2003.00118.x|pmid=12911813|s2cid=25646573|doi-access=free}}</ref>

The vacuole probably evolved several times independently, even within the [[Viridiplantae]].<ref name="Becker2" />