Movement Through Cell Boundaries

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Movement Through Cell Boundaries

• Active and Passive Transport

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Diffusion
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Osmosis is a form of diffusion, the movement of
molecules from an area of greater concentration
to an area of lesser concentration
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But osmosis is the movement of water molecules
through a membrane.
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Osmosis and Cell Turgor

• How cells move water to stay firm (that is called
  cell turgor) or not (that is called wilting)

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Add Salt Water

• Water moves by osmosis from an area of greater
  concentration (inside the cell) to an area of
  lesser concentration (out of the cell) and the
  membrane collapses

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Add Distilled Water

• Water moves by osmosis from an area of greater
  concentration (outside the cell) to an area of
  lesser concentration (cell interior) causing an
  expansion

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Facilitated Diffusion

• Special channels
• Specific to certain molecules
• Help speed their diffusion

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Since the energy of the molecules does all the
work, and no work is required by the cell,
diffusion and osmosis are called forms ofPASSIVE
TRANSPORT
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ACTIVE TRANSPORT is when the cell must actively
work and use its own energy to move molecules
around, as well as in and out of the cell.
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Endocytosis-pockets form and engulf particles
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Endocytosis
Exocytosis
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Pinocytosis

• Take in liquids
• Otherwise the same as other forms of endocytosis

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Phagocytosis

• Cell eating
• Cell extends around particles/engulfs them
• Uses less energy than it acquires
• Amoeba