BIOL380 Week 5 Transport Across Membranes

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  1. What type of molecules pass directly through phospholipid membranes?
    • Many Hydrophobic molecules (steroids)
    • Water only in very small amounts
    • Some small hydrophilic molecules (ethanol)
  2. What type of molecules DO NOT pass through the membranes?
    • Most hydrophilic molecules
    • Ions
    • Hydrophobic molecules attached to hydrophilic components
  3. Molecules that cannot pass directly through the membrane need what 3 kinds of assistance?
    • Channels
    • Transporters
    • Pumps
  4. What kinds of proteins comprise Channels?
    Transmembrane Proteins
  5. Are Channels selective or nonselective for specific ions or molecules?
  6. How many ions/molecules do Channels allow to pass per unit of time?
    10 million ions/molecules per second
  7. Transporters are comprised of what?
  8. How do Transporters work?
    Specific ions/molecules bind to Binding Sites and cause a conformation in the Trasnporter
  9. How many ions/molecules do Transporters allow to pass per unit time?
    10,000 per second
  10. What are Pumps comprised of?
  11. How do Pumps work?
    • Has binding sites for specific Ions/Molecules
    • Has an ATP binding site
    • Requires ATP to pump molecules across the membrane
  12. How many ions/molecules do Pumps allow to pass per unit time?
    1000 per second
  13. When do Chemical Gradients occur?
    When each side of the membrane has a different concentration of the ions or molecules to be transported.
  14. What do Electrical Gradients occur?
    When the charge on one side of the membrane is different than the charge on the other side.
  15. Na+ and Cl- are concentrated where? Intracellular or Extracellular?
  16. K+ and Multiple Anions are concentrated where? Extracellular or Intracellular?
  17. When an ion/molecule is more concentrated on one side of the membrane, it is said to have what?
    A Concentration/Chemical Gradient
  18. Membranes are non-permeable, semi-permeable, completely permeable?
  19. If possible, concentration gradients will try to equalize by moving ions/molecules across the membrane by moving which direction in the concentration gradient?
    Movement down the concentration gradient
  20. Molecules with no charge will pass through the membrane until they have equal what?
    Concentrations on each side of the membrane
  21. What is the Equilibirum Charge or Resting Charge of the Cell normally?
  22. Movement of molecules/ions will occur without the input of energy as long as they are moving which direction along the concentration or electric gradients?
    Moving down
  23. Movement against the concentration or electrical gradient required what?
  24. What are two types of Channels?
    Passive and Gated
  25. K+ will move through the Passive Channel down its concentration gradient until the movement is opposed by what?
    The Electrical Gradient
  26. Gated Channels are normally closed or open?
  27. What is required for a Gated Channel to open temporarily?
  28. What are 3 Stimuli that could open a Gated Channel?
    • Chemicals/Ligand
    • Voltage
    • Mechanical Stimuli
  29. Gated channels alternate between what (3) states?
    • Open
    • Closed and Incapable of Opening temporarily - allowing time to reset itself
    • Closed and Capable of Opening
  30. What are the 3 types of Transporters?
    • Uniporter
    • Symporter
    • Antiporter
  31. What is the function of the Uniporter and what is its restriction?
    • Trasnporters one molecular type across the membrane.
    • Restriction is that molecules must move down their concentration gradient.
  32. What is the function of the Symporter and what is its restriction?
    • Transporters at least two types of molecules across the membrane.
    • Restriction is that both molecule types must be moved in the same direction across the membrane.
  33. What is the function of the Antiporter and what is its restriction?
    • Transporters at least two types of molecules across the membrane.
    • Restriction is that molecule types are moved in opposite directions across the membrane.
  34. For Symporters and Antiporters, at least one molecule type must move in what direction?
    Move down its electrochemical gradient

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BIOL380 Week 5 Transport Across Membranes
2011-10-02 02:12:59
BIOL380 Week Transport Across Membranes

BIOL380 Week 5 Transport Across Membranes
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