|MadSci Network: Botany|
When exposed to salt water, fresh water Elodea cells lose water, and the cell membrane pulls away from the cell wall. This is termed plasmolysis. The underlying process is diffusion of water from a higher concentration within the cell membrane to a lower concentration outside the cell membrane. Diffusion of water across a selectively permeable cell membrane is termed osmosis. The membrane is selectively permeable because virtually none of the salt crosses the membrane while the water passes freely across. In ocean plants, the cell membrane allows salt to enter the cell and accumulate in the cell vacuole. This allows the cells to accumulate a higher salt concentration than the salt concentration in the sea water. Their cells do not plasmolyze. Scientists have recently isolated a single gene that allows salt to cross the cell membrane. When the gene was transferred into a tomato plant, it made the tomato salt tolerant. References Elodea Plasmolysis Plasmolysis Plasmolysis in Elodea Plant Cells Gene Makes Tomatoes Tolerate Salt
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