Passive Transport Diffusion Osmosis

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Passive TransportDiffusionOsmosis

• Biology
• Unit - Regulation

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Diffusion

• Involves the movement of molecules from an area
  of high concentration to an area of low
  concentration
• Does not require energy (ATP)

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Examples of Diffusion
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Diffusion

• The movement of a substance down its
  concentration gradient

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Equilibrium

• even at equilibrium the molecules move at random

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Equilibrium
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Osmosis

• Is
• all
• about
• the
• movement
• of
• WATER
• molecules

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Learning Osmosis

• Water molecules diffuse from an area of low
  solute concentration to an area of high solute
  concentration

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Learning Osmosis

• Water molecules diffuse from an area of high
  water concentration to an area of low water
  concentration

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Isotonic

• When the concentration of solutes outside and
  inside the cell are equal.

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Hypertonic

• When the concentration of solute molecules
  outside the cell is higher than the concentration
  in the cytosol
• The solution outside the cell is hypertonic to
• the cytosol

                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                             
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Hyper highHypertonic
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Hypotonic

• When the concentration of solute molecules
  outside the cell is lower than the concentration
  in the cytosol
• The solution outside the cell is hypotonic to
• the cytosol

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Hypo lowHypotonic
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Effect of  Solutions on Cells
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How do cells deal with Osmosis?

• 1) cells in hypotonic environment ?
  unicellular freshwater organisms (paramecium)
• water constantly diffuses in
• They require low concentration of water in
  cytosol
• need to get rid of excess
• water

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How do cells deal with Osmosis?

• do this with contractile vacuoles
• organelles that remove water
• collect water and pump it out of cell

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How do cells deal with Osmosis?

• 2) some cells cannot compensate for changes in
  solute concentration
• red blood cells ? lose their normal shape when
  placed in an environment that is not isotonic to
  their own

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Alright.

• Lets
• test
• your
• new
• knowledge.

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What has happened to this cell?

• Explain.