Osmosis

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Osmosis

• A Special Case of Diffusion

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Osmosis is the passive transport of water.

• Osmosis the diffusion of water molecules across
  a selectively permeable membrane.
• In large part, the cell is made of solution
  water mixed with different solids.
• This water can easily move across the cells
  membrane.
• Water will move from areas of high concentration
  (of water) to areas of low concentration.

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Osmosis is the passive transport of water.

• Stated in other terms, water will travel down its
  concentration gradient (from high to low).
• Once the water has moved across a membrane and
  diffuses no more it is at equilibrium.

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Osmosis is the passive transport of water.

• The concentration of a solution is made of two
  parts
• A solvent is the liquid (water) part of a
  solution.
• A solute is the particle (salt, sugar, etc) that
  floats (dissolved) in the liquid solvent.

(6 solutes)
(13 solutes)
Solvent (water)
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The results show that water diffused from the
left to the right.
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Water balance between cells and their
surroundings is important.
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Water balance between cells and their
surroundings is important.
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Water balance between cells and their
surroundings is important.
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Water balance between cells and their
surroundings is important.
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• Hypertonic Solution
• The concentration of solutes in the cell is less
  than the concentration solutes outside the cell.
• The concentration of water in the cell is greater
  than outside the cell.
• Effect shriveling of cell

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• Hypotonic Solution
• The concentration of solutes in the cell is
  greater than the concentration of solutes outside
  the cell.
• The concentration of water in the cell is less
  than outside the cell.
• Effect swelling of cell

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• Isotonic Solution
• The concentration of solutes in the cell is the
  same as the concentration of solutes outside the
  cell.
• The concentration of water in the cell is the
  same outside the cell.
• Effect No change in cell shape or size.

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Complete the scenarios (1-5)

• 5 points per scenario (problem)
• Determine what the percentages of water and
  solute are.
• State which direction the water will diffuse.
• Draw arrow that shows the water concentration
  gradient.
• Identify if cell is hyper-, hypo-, or isotonic.
• What will the effect be for the cell?
• Lets do scenario 1 together!