Download Bell Work: The cell membrane is selectively permeable, what does

passivetransport.notebook
September 26, 2013
Friday, September 27
Bell Work:
The cell membrane is selectively permeable, what does that mean?
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passivetransport.notebook
September 26, 2013
Passive Transport­ Movement of molecules across a cell membrane without energy input from the cell.
­Small lipids, CO2 and O2 easily diffuse across the membrane.
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passivetransport.notebook
September 26, 2013
Diffusion­ movement of molecules in a fluid or gas from a region of higher concentration to a region of lower concentration.
Concentration Gradient­ Differences in concentration of a substance from one location to another.
­Molecules diffuse from an area of higher concentration to an area of lower concentration.
Dynamic Equilibrium­ Concentration is equal but molecules are still moving.
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passivetransport.notebook
September 26, 2013
Facilitated Diffusion­ diffusion of molecules across a membrane through transport proteins.
­transport proteins make it easier for the molecules to enter and exit the cell.
­Still requires no energy
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passivetransport.notebook
September 26, 2013
Monday, September 30
Bell Work:
What is facilitated diffusion? How is it different from diffusion?
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passivetransport.notebook
September 26, 2013
Osmosis­ movement of water across a membrane from an area of higher water concentration to an area of lower water concentration.
Isotonic
Hypotonic
(Equal (Under
Pressure) Pressure)
Hypertonic
(Over
Pressure)
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passivetransport.notebook
September 26, 2013
Isotonic
• The solution a cell is in has the same concentration of dissolved particles as the cell itself.
• H2 O moves in and out of the cell at an equal rate.
• Cell's size remains constant
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September 26, 2013
Isotonic
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Hypotonic
• A solution has a lower concentration of dissolved particles than the cell.
• Water diffuses into the cell
• If too much water enters the cell membrane could burst.
• Some animals and single­celled organisms have adaptations to survive hypotonic envrionments
• Cells increase in size.
• Grocery stores mist water on produce.
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September 26, 2013
Hypotonic
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September 26, 2013
Hypertonic
• A solution has a higher concentration of dissolved particles than the cell.
• Water flows out of the cell
• Animal cells shrivel and die
• Cells decrease in size
• Plant cells plasma membrane and cytoplasm shrink away from the cell wall
• Causing wilting of plants.
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September 26, 2013
Hypertonic
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