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Introduction to Membrane Transport definitions

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  • Biological Membrane
    A selectively permeable barrier that controls which molecules can enter or exit a cell based on specific properties.
  • Selective Permeability
    A property allowing only certain molecules to cross a membrane while restricting others, based on size, charge, and polarity.
  • Diffusion
    The movement of molecules from an area of high concentration to low concentration, which may or may not require facilitation.
  • Hydrophobic Molecule
    A nonpolar substance that can easily pass through membranes due to its lack of affinity for water.
  • Hydrophilic Molecule
    A polar or charged substance that cannot freely cross membranes and often requires protein assistance.
  • Molecular Transport
    The movement of small molecules across membranes, including both passive and active mechanisms.
  • Bulk Transport
    The movement of large molecules or particles across membranes, typically involving vesicle formation.
  • Passive Transport
    A process where molecules move across membranes without energy input, including diffusion and osmosis.
  • Active Transport
    A process requiring energy to move molecules across membranes, often against their concentration gradient.
  • Osmosis
    The passive movement of water molecules across a selectively permeable membrane.
  • Facilitated Diffusion
    A passive process where molecules cross membranes with the help of proteins, without energy input.
  • Endocytosis
    A bulk transport mechanism where cells engulf large particles or fluids by forming vesicles from the membrane.
  • Exocytosis
    A bulk transport process where cells expel large molecules or particles by fusing vesicles with the membrane.
  • Phagocytosis
    A type of endocytosis where cells engulf large particles, often referred to as cellular eating.
  • Pinocytosis
    A type of endocytosis where cells take in extracellular fluid, often described as cellular drinking.