osmosis/diffusion/active transport
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TRANSCRIPT
Diffusion and Osmosis
• Diffusion - the tendency of molecules to move from a higher concentration to a lower concentration until equilibrium is reached.
Higher concentration on the left
Equilizing outEqual on right & left
Fully diffused
Diffusion video
Passive Transport • 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 doesn’t open up, just goes through.
Only works with very small particles.
Osmosis VideoQuickTime™ and a
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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
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
Isotonic Solution
• Equal amount of water goes in and out of cell.
Video link
Effect on living cells
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Active Transport• Cell uses energy to move things in and out. Example:
food molecules• Cell membrane actually opens and closes.
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Active Transport Video
Exocytosis & Endocytosis
Endocytosis (substances “enter” the cell).
Ex: Food molecules
Exocytosis (molecules “exit” the cell.
Ex: Waste products