Cell Transport

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Cell Transport
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Cell Transport

• 2 kinds of transport
• Passive Transport
• Does NOT require energy
• Diffusion, Facilitated Diffusion, Osmosis
• Substances cross the membrane down their
  concentration gradient
• Active Transport
• REQUIRES energy
• Endocytosis and Exocytosis
• Substances cross the membrane against their
  concentration gradient

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Passive Transport Diffusion

• Does NOT use energy
• Things move from an area of high concentration to
  an area of low concentration

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Passive Transport Facilitated Diffusion

• Does not use energy
• Uses transport proteins to move large molecules
  thru the membrane
• Moves molecules from areas of high concentration
  to areas of low concentration

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Osmosis

• Diffusion of water across a membrane
• Moves from HIGH concentration to LOW concentration

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Cells in Solutions

• In Hypotonic Solutions, the inside has less
  solute than the outside so water will move IN to
  the cell
• In Hypertonic Solutions, the inside has more
  solute than the outside so water moves OUT of the
  cell
• In Isotonic Solutions, the amount of solutes is
  equal on both sides of the membrane, so water
  does not move at all

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Effects of Osmosis

• When cells are in a hypotonic solution, they will
  swell
• Cell wall in plants keep cells from bursting
• Swelling causes the stems and leaves to be rigid
• In an isotonic environment, plants wilt

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Active Transport

• REQUIRES energy or ATP
• Moves materials against their concentration
  gradient
• From an area of low concentration to an area of
  high concentration

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Active Transport

• Large molecules need help moving into and out of
  the cell or against their concentration gradient
• Movement of large molecules OUT of the cell is
  exocytosis
• Movement of large molecules into the cell is
  endocytosis

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Endocytosis

• The movement of large molecules into the cell
• Cell membrane forms a pouch around the substance
  and the pouch pinches off to form a vessicle
  inside of the cell

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Exocytosis

• The opposite of endocytosis
• Large molecules that are made inside the cell are
  transported outside of the cell membrane
• Vesicles form inside the cell and fuse with the
  membrane. The contents of the vesicle are
  released outside of the cell