Active Transport

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Active Transport

• Cell Membrane Pumps and Vesicle Transport

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Active Transport

• Active transport - movement of materials AGAINST
  the concentration gradient from low concentration
  to high concentration
• Requires the cell to use energy (ATP)
• 2 kinds
• 1. membrane pumps
• 2. vesicle transports

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1. Cell Membrane Pumps

• Involve carrier proteins called cell membrane
  pumps to move materials against the concentration
  (UP concentration gradient)
• Similar to the steps of facilitated transport.
• Results in electrical impulses across nerve cells
• Ex. Sodium-Potassium Pump

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2. Vesicle Transport

• Some substances (ex. Food) are too BIG to pass
  through membrane
• OR
• large quantities need to pass through the cell
• These situations use vesicle transport
• Two kinds
• Endocytosis
• Exocytosis

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Endocytosis

• Cells ingest external fluid, macromolecules
  large particles (including other cells)
• External materials are enclosed by part of the
  cell, forming a pouch
• The pouch pinches off cell membrane becomes a
  membrane bound organelle called ? a vesicle
• Vesicles can fuse with lysosomes to digests
  contents.
• Two kinds of Endocytosis
• Phagocytosis movement of large particles or
  whole cells. Possible feeding method, or a
  method of defense to destroy bacteria/viruses
• Pinocytosis transport of solutes or liquids

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• Pinocytosis
• (cartoon animation)

• Phagocytosis (cartoon animation)

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Phagocytosis(taking place in cells under a
microscope)
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Endocytosis
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Exocytosis (Reverse of endocytosis)

• Vesicles in cytoplasm fuse with cell membrane and
  RELEASE their contents into the external
  environment OUTSIDE the cell
• Used to release large molecules such as proteins
  packaged by the golgi apparatus
• Used in nervous
• endocrine system to
• control activities in
• other cells.

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Exocytosis
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Endocytosis Exocytosis
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Endocytosis

• http//www.maxanim.com/physiology/Endocytosis20an
  d20Exocytosis/Endocytosis20and20Exocytosis.htm