Diffusion and Osmosis

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Diffusion and Osmosis
Cell Processes
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• Diffusion - the tendency of molecules to move
  from a higher concentration to a lower
  concentration until equilibrium is reached.

Equal on right left Fully diffused
Higher concentration on the left
Equilizing out
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Diffusion video
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Passive Transport

Types of Movement in the Cell

• Diffusion across a semi-permeable membrane (ex
  cell membrane).
• Cell does not use any energy for diffusion. It
  goes through the cell membrane without it opening
  up.
• Examples water, alcohol, O2 and CO2,

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• Osmosis - The diffusion of water
• Cell membrane doesnt open up, just goes through.
  Only works with very small particles.

Osmosis Video
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Hypertonic Solution

• Solution with a higher concentration of solute
  and a lower concentration of water.
• Makes the cell shrivel. Example adding salt
  water

Video Link
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Hypotonic Solution

• Solution with a lower solute concentration and a
  higher water concentration.
• More water moves in than out. Cell bloats.
  Example Being in the bath too long causes
  wrinkled fingers.

Video link
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Isotonic Solution

• Equal amount of water goes in and out of cell.

Video link
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Effect on living cells
Animal
Plant
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Active Transport

• Cell uses energy to move things in and out.
  Example food molecules
• Cell membrane actually opens and closes.

Active Transport Video
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Exocytosis Endocytosis
Exocytosis (molecules exit the cell. Ex Waste
products

• Endocytosis (substances enter the cell).
• Ex Food molecules