7.3 Cell Transport

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7.3 Cell Transport
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Cell Membrane

• Remember! The cell membrane regulates what goes
  in and out of the cell.
• Made out of a lipid bilayer (two layers). Which
  makes it flexible and a strong barrier.
• Made of lipids which have a hydrophilic (water
  loving) heads and hydrophobic (water hating)
  fatty acid tails.

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Cell Membrane

• Cell membrane is selectively permeable
  (semipermeable). This means it only lets certain
  materials pass through.
• Permeable means it allows materials pass through.
• Proteins are embedded into the membrane to form
  channels and pumps to help move materials across
  the membrane.
• Known as the fluid mosaic model.

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Transport Across the Membrane

• One of the most important jobs of the cell
  membrane is to keep the cells internal
  environment stable. It does this by regulating
  what goes in and out of cell.
• There are several methods that allow materials to
  pass through a membrane.
• Passive Transport Movement across the membrane
  without using cellular energy
• Active Transport Movement across the membrane
  using cellular energy.

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Passive Transport

• Diffusion the process by which particles move
  from an area of high concentration to an area of
  lower concentration.

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Passive Transport

• Facilitated Diffusion molecules passing through
  protein channels because they cannot directly
  diffuse through the membrane. (It is fast and
  specific)
• Aquaporins water channel proteins that allow
  water to pass right through.

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Passive Transport

• Osmosis The diffusion of water through a
  selectively permeable membrane.
• Moves from high concentration to lower
  concentration

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How Osmosis Works
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Active Transport

• Moving materials against the concentration
  gradient.
• Requires energy!
• Protein Pumps- found on the membrane and pumps
  molecules across the membrane from low to high
  concentration.
• Move ions like sodium, potassium and calcium
  across the membrane.

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Active Transport

• Moving Large Molecules into and out of the cell.
• Endocytosis taking material into the cell the
  cell by folding and making pockets (vesicles)
  from the cell membrane into the cytoplasm
• Phagocytosis taking in a solid (usually food
  vacuole)
• Ameobas use this process to eat.
• Pinocytosis taking in a liquid
• Exocytosis releasing large amounts of material
  from a cell. A vesicle fuses with the plasma
  membrane to push the material out.

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Endo- Exo- cytosis
http//www.youtube.com/watch?vK7yku3sa4Y8