Diffusion

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Explain what is happening in this clip.
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Objective You will be able to explain how
molecules move across a semi-permeable membrane
due to a concentration gradient.Diffusion
Osmosis
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Diffusion

• The movement of molecules from an area in which
  they are highly concentrated to an area in which
  they are less concentrated.

4
See an animation of diffusion here

• http//lewis.eeb.uconn.edu/lewishome/applets/Diffu
  sion/diffusion.html

5
How did the lab illustrate diffusion? Explain or
draw a diagram
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Osmosis

• The diffusion of water across a selectively
  permeable membrane.

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Osmosis

•  
• Water moves from a high concentration of water
  (less salt or sugar dissolved in it) to a low
  concentration of water (more salt or sugar
  dissolved in it).  This means that water would
  cross a selectively permeable membrane from a
  dilute solution (less dissolved in it) to a
  concentrated solution (more dissolved in it).

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What happens when the concentration of water
differs on both sides of a membrane?
http//www.usd.edu/bgoodman/Osmos.htm
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See an animation of osmosis here

• http//lewis.eeb.uconn.edu/lewishome/applets/Osmos
  is/osmosis.html

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Animal cells in WATER

• In this picture a red blood cell is put in a
  glass of distilled water (all water with no salt
  or sugar in it).  Because there is a higher
  concentration of water outside the cell, water
  enters the cell by OSMOSIS.  In this case too
  much water enters and the cell swells to the
  point of bursting open.  In the end pieces of
  cell membrane are left in the water.

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Isotonic cells
Hypotonic cells
Hypertonic cells
Normal
Distilled water
Salt water
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Define selectively permeable membrane
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Selectively permeable membrane

• A membrane that allows only certain materials to
  cross it
• Materials pass through pores in the membrane

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For more information on diffusion osmosis,
click here

• http//edtech.clas.pdx.edu/osmosis_tutorial/defaul
  t.html

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Why are osmosis diffusion important?
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Why are osmosis diffusion important?

• All living things have certain requirements they
  must satisfy in order to remain alive maintain
  homeostasis
• These include exchanging gases (usually CO2 and
  O2), taking in water, minerals, and food, and
  eliminating wastes.
• These tasks happen at the cellular level.
• Molecules move through the cell membrane by
  diffusion

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Why are osmosis diffusion important?

• All living things have certain requirements they
  must satisfy in order to remain alive. These
  include exchanging gases (usually CO2 and O2),
  taking in water, minerals, and food, and
  eliminating wastes. These tasks ultimately occur
  at the cellular level, and require that molecules
  move through the membrane that surrounds the
  cell.

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Why are osmosis diffusion important?

• This membrane is a complex structure that is
  responsible for separating the contents of the
  cell from its surroundings, for controlling the
  movement of materials into and out of the cell,
  and for interacting with the environment
  surrounding the cell.