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Osmosis
Goal: I will be able to explain the
process of diffusion and osmosis as they
relate to cells.
Imagine
Have you ever gone to the ‘fridge’ and
notice the celery has gone limp?
What happened?
As the celery loses water
it becomes limp.
Water molecules are so small they travel
across cell membranes by diffusion.
When water diffuses across a selectively
permeable membrane it is called
Osmosis
Cells and concentrated
solutions
The movement of water in and out of
cells is vital to living things and is driven
by imbalances in concentrations.
Ideally solute concentration outside the
cell is equal to that inside the cell.
Usually in cells, sugars and salts are
common solutes, and water is the solvent
Isotonic Solutions: contain the same
concentration of solute as in another
solution (e.g. the cell's cytoplasm).
When a cell is placed in an isotonic
solution, the water diffuses into and out
of the cell at the same rate.
Hypotonic Solutions: contains a low concentration of solute relative to another solution (e.g. the cell's cytoplasm).
https://www.youtube.com/watch?v=OYoaLzobQmk
https://www.youtube.com/wa
tch?v=gWkcFU-hHUk
Hypertonic Solutions: contain a high
concentration of solute relative to another
solution (e.g. the cell's cytoplasm).
https://www.youtube.com/watch?v=lzDlGl3
b4is&feature=related