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Passive Transport: Diffusion and Osmosis definitions

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  • Passive Transport
    Movement of molecules across membranes without energy input, typically from high to low concentration, maintaining equilibrium.
  • Diffusion
    Unassisted movement of molecules toward equilibrium, favoring small, uncharged, non-polar substances across membranes.
  • Simple Diffusion
    Direct passage of small, non-polar molecules through membranes, driven by concentration gradients and lipid solubility.
  • Facilitated Diffusion
    Assisted movement of molecules across membranes via proteins, still following concentration gradients without energy use.
  • Channel Protein
    Membrane protein forming a passageway for specific molecules or ions to cross without conformational changes.
  • Carrier Protein
    Membrane protein that binds molecules and undergoes shape changes to transport them across membranes.
  • Transport Protein
    General class of membrane proteins enabling movement of substances across cell membranes, including channels and carriers.
  • Uniport
    Transport mechanism moving a single type of molecule across a membrane, typically the fastest facilitated diffusion method.
  • Symport
    Transport system moving two different molecules simultaneously in the same direction across a membrane.
  • Antiport
    Transport system moving two different molecules in opposite directions across a membrane, crucial for cellular regulation.
  • GLUT1
    A glucose transporter functioning as a uniport, essential for glucose uptake in cells like those of the gut and intestines.
  • Sodium-Calcium Antiporter
    Membrane protein exchanging sodium and calcium ions in opposite directions, vital for muscle contraction regulation.
  • Osmosis
    Diffusion of water across semipermeable membranes, driven by differences in solute concentration.
  • Osmotic Pressure
    Pressure required to halt water movement across a membrane, determined by solute concentration differences.
  • Aquaporin
    Channel protein facilitating rapid water movement across membranes via hydrogen bonding, without shape changes.