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Simple and Facilitated Diffusion definitions

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  • Passive Transport
    Movement of molecules across cell membranes without energy input, following concentration gradients.
  • Concentration Gradient
    Difference in the concentration of a substance across a space, driving passive transport.
  • Simple Diffusion
    Direct movement of small uncharged molecules through the cell membrane without protein assistance.
  • Facilitated Diffusion
    Transport of charged molecules across cell membranes with the help of transport proteins.
  • Transport Proteins
    Proteins that assist in moving substances across cell membranes in facilitated diffusion.
  • Porins
    Channel-forming proteins that create membrane-spanning tunnels for molecule passage.
  • Channels
    Membrane-spanning tunnels formed by proteins to allow molecule movement across membranes.
  • Aquaporins
    Specialized porins that facilitate rapid water transport across cell membranes.
  • Transporters
    Carrier proteins that undergo conformational changes to move molecules across membranes.
  • Carriers
    Proteins that transport molecules by changing shape, open to one side of the membrane at a time.
  • Osmosis
    Diffusion of water across a semipermeable membrane, often facilitated by aquaporins.
  • Ion Channels
    Channels that allow ions to pass through the membrane, facilitating their diffusion.
  • Conformational Change
    Structural alteration in a protein that enables it to transport molecules across membranes.
  • Phospholipids
    Molecules forming the cell membrane, allowing small uncharged molecules to pass through.