Plasmolysis

Plasmolysis

Plasmolysis is the contraction of cells due to the loss of water through osmosis in plants and bacteria. Osmosis is the net diffusion of water across a selectively permeable membrane, such as a cell membrane, from an area with a high water potential to an area with a low water potential. [cite web
url=http://www3.interscience.wiley.com/journal/119265683/abstract?CRETRY=1&SRETRY=0
title=Wiley InterScience :: JOURNALS :: New Phytologist
publisher=www3.interscience.wiley.com
accessdate=2008-09-11
last=
first=]

Turgidity

A plant cell in a more dilute salt solution will absorb water by endosmosis, so that the increased volume of water in the cell will increase pressure, making the protoplasm push against the cell wall, a condition known as turgor. Turgor makes plant cells push against each other in the same way and is the main method of support in non-woody plant tissue. Plant cell walls resist further water entry after a certain point, known as full turgor, which stops plant cells from bursting as animal cells do in the same conditions.

Plasmolysis

If a plant cell is placed in a more concentrated salt (hypertonic) solution, the plant cell loses water and hence turgor pressure, making the plant cell flaccid. Plants with cells in this condition wilt. Further water loss causes plasmolysis: pressure decreases to the point where the protoplasm of the cell peels away from the cell wall, leaving gaps between the cell wall and the membrane. Eventually cytorrhysis – the complete collapse of the cell wall – can occur. There is no mechanism in plants to prevent excess water loss in the same way as excess water gain, but plasmolysis can be reversed if the cell is placed in a weaker solution (hypotonic solution). The equivalent process in animal cells is called crenation. The liquid content of the cell leaks out due to diffusion. The cell collapse and cell membrane pulls away from the cell wall

Plasmolysis only occurs in extreme conditions and rarely happens in nature. It is induced in the laboratory by immersing cells in strong saline or sugar solutions to cause exosmosis, often using Elodea plants or onion epidermal cells, which have coloured cell sap so that the process is clearly visible.

ee also

*Crenation
*Cytolysis, where the cell bursts rather than shrinks.

References

External links

* [http://www.pgjr.alpine.k12.ut.us/science/whitaker/Cell_Chemistry/Plasmolysis.html Pictures of plasmolysis in Elodea and onion skin]
* [http://3e.plantphys.net/article.php?ch=3&id=31 Wilting and plasymolysis]


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Look at other dictionaries:

  • plasmolysis — (n.) 1883, from Fr. plasmolysis (1877), from plasmo (see PLASMA (Cf. plasma)) + Gk. lysis a loosening (see LYSIS (Cf. lysis)) …   Etymology dictionary

  • plasmolysis — plasmolysis. См. плазмолиз. (Источник: «Англо русский толковый словарь генетических терминов». Арефьев В.А., Лисовенко Л.А., Москва: Изд во ВНИРО, 1995 г.) …   Молекулярная биология и генетика. Толковый словарь.

  • plasmolysis — [plaz mäl′i sis] n. [ModL: see PLASMO & LYSIS] Biol. a shrinking of the protoplasm of a living cell due to loss of water by osmosis …   English World dictionary

  • plasmolysis — Shrinking of plant cells by osmotic loss of cytoplasmic water. SYN: protoplasmolysis. [plasmo + G. lysis, dissolution] * * * plas·mol·y·sis plaz mäl ə səs n shrinking of the cytoplasm away from the wall of a living cell due to water loss by… …   Medical dictionary

  • plasmolysis — n. a process occurring in bacteria and plants in which the protoplasm shrinks away from the rigid cell wall when the cell is placed in a hypertonic solution. Plasmolysis is due to withdrawal of water from the cell by osmosis …   The new mediacal dictionary

  • plasmolysis — noun Etymology: New Latin Date: 1883 shrinking of the cytoplasm away from the wall of a living cell due to outward osmotic flow of water • plasmolytic adjective …   New Collegiate Dictionary

  • plasmolysis — (plaz mol ī sis) The process in which water osmotically leaves a cell, which causes the cytoplasm to shrivel up and pull the plasma membrane away from the cell wall …   Dictionary of microbiology

  • plasmolysis — Process by which the plant cell protoplast shrinks, so that the plasma membrane becomes partly detached from the wall. Occurs in solutions of high osmotic potential, due to water moving out of the protoplast by osmosis …   Dictionary of molecular biology

  • plasmolysis — plasmolytic /plaz meuh lit ik/, adj. plasmolytically, adv. /plaz mol euh sis/, n. Bot. contraction of the protoplasm in a living cell when water is removed by exosmosis. [1880 85; PLASMO + LYSIS] * * * …   Universalium

  • plasmolysis — noun the shrinking of protoplasm away from the cell wall of a plant or bacterium due to water loss …   Wiktionary

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