The process of osmosis and its importance to living organisms
Osmosis is the process by which there is a net movement of water through a semi permeable membrane from an area of high water potential to an area of low water potential. Within a cell, osmosis has the following effect. If the water potential of the cell is lower than that around the cell water will move across a concentration gradient into the cell. If this is the case, the increase in water in the cell, may cause the cell to swell, which could consequently lead to the cell bursting. If the concentration of water is the same both inside the cell and surrounding the cell there will be a dynamic equilibrium between the number of water molecules entering and leaving the cell, hence the cell does not change size. For example, red blood cells in the blood plasma retain their shape because of the isotonic nature of the plasma. If the concentration of water is higher within the cell then that of outside the cell, there will be a net movement of water out of the cell, this will cause the cell to shrink and shrivel.
Within animal cells there is no cell wall therefore when there is a higher water potential outside the cell to inside the cell, water diffuses into the cell, and as there is no cell wall to prevent it from bursting, the cell swells and bursts and the cell cannot become turgid. However when an animal cell is in danger of bursting, organelles within the cell pump water out of the cell to prevent this from happening. When a cell contains excess fluid it causes the membrane to split and the cell to burst, when this happens due to an over abundance of fluid, it is known as lysis. It is therefore very important to maintain an osmotic balance within animal cells. Like with all cells when the water potential inside the cell is higher than that outside the cell water moves out of the cell, causing the cell to shrink in size. Therefore it is necessary for animal cells to be always surrounded by an...
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