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Hypotonic Environments

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Hypotonic Environments

Postby Bio_Girl015 » Fri Apr 14, 2006 3:51 am

How do bacteria and protozoa adapt to live in hypotonic environments? Don't the bacterial cells burst? If someone could please explain this to me i'd be very grateful because right now I am quite confused. Thank you in advance. :?:
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Postby kiekyon » Fri Apr 14, 2006 5:38 am

The question has to be addressed with an understanding that both hypertonic (such as salt water) and hypotonic solutions (such as freshwater) can be harmful to cells. The type of damage will depend to a large extent on the type of cell (i.e. eukaryotic or prokaryotic, with or without cell wall etc) and of course on the ability of the cell to compensate for osmotic effects.

Specifically, a typical mammalian cell can not withstand too much deviation from normal osmolarity (isotonic solution) because the cellular membrane is quite weak and can burst from increased internal pressure if the cell is exposed to hypotonic solutions. In hypertonic solutions, these cells shrink, causing severe disbalance in cytoplasm composition and also an overload of export-import molecular pumps and channels, which eventually leads to cell death.

For more hardy, walled cells such as many bacteria, plants, algae, etc. the increase in cell volume is controlled by the mechanical resistance of the cell wall. Walled bacteria can therefore withstand a lot harsher environments than 'naked' mammalian cells, for example. Certain organisms have adapted to living in extremely hypertonic environments - they compensate for volume loss by e.g. creating gas bubbles in the hytoplasm, increasing concentration of protective substances (e.g. sugars, etc.) and so forth.
Last edited by kiekyon on Tue Apr 18, 2006 12:59 pm, edited 3 times in total.
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Postby Bio_Girl015 » Mon Apr 17, 2006 6:36 pm

Thanks for your help on this.I totally understand now.Thanks again kiekyon!
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Postby kiekyon » Wed Apr 19, 2006 2:54 am

Bio_Girl015 wrote:Thanks for your help on this.I totally understand now.Thanks again kiekyon!


u r welcome :roll:
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