Active/Passive Transport

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Active/Passive Transport
2015-01-25 18:57:52
BIO 183,Exam I,Cells I
Trasnportin' all sorts of stuff
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  1. Diffusion
    • spontaneous movement of ions or molecules along a concentration gradient 
    • From an area of high concentration to an area of low concentration
    • No energy required
  2. Osmosis
    Diffusion of water through a semi-permeable membrane
  3. Facilitated Diffusion
    Passive diffusion aided by proteins
  4. Channel Proteins
    • have a hydrophilic channel that certain molecules or ions can use as a tunnel through the membrane
    • Can open or close if needed
    • e.g Aquaporins (for water), ion channels
  5. Carrier Proteins
    bind to molecules and change shape to shuttle them across the membrane
  6. Types of Carrier Proteins
    • Uniporter
    • Symporter
    • Antiporter
  7. Uniporter
    single solute moves in 1 direction
  8. Symporter
    two solutes move in same direction
  9. Antiporter
    two solutes move in opposite direction
  10. Active Transport
    • Uses energy to pump ions or molecules against their concentration gradient
    • Performed by specific proteins embedded in the membranes
    • Requires energy
    • e.g. Sodium Potassium Pump
  11. Electrochemical Gradient
    the two combined forces that drive the diffusion of ions across a membrane
  12. Membrane Potential
    • Voltage across a membrane
    • Inside of the cell is negative compared to the outside
    • Potential favors passive transport of cations into the cell and anions out of the cell
  13. Electrogenic Pumps
    • generate the voltage gradient across a membrane
    • helps put cells back to rest after ATP
  14. Secondary Active Transport
    Mechanism where an ATP-powered pump that transports one solute can indirectly drive the active transport of several other solutes