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Introduction to Membrane Transport definitions

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  • Biological Membranes
    Structures that are selectively permeable, allowing certain molecules to cross based on size, charge, and polarity.
  • Selectively Permeable
    Characteristic of membranes that allows selective passage of substances while blocking others.
  • Passive Transport
    Movement of molecules across membranes without energy input, including osmosis and diffusion.
  • Active Transport
    Energy-requiring process that moves molecules across a membrane against a concentration gradient.
  • Osmosis
    Passive transport of water molecules across a selectively permeable membrane.
  • Simple Diffusion
    Movement of small, nonpolar molecules across a membrane without assistance.
  • Facilitated Diffusion
    Passive transport of molecules across a membrane via specific transport proteins.
  • Endocytosis
    Bulk transport process where cells engulf external substances into vesicles.
  • Exocytosis
    Process by which cells expel materials in vesicles to the extracellular environment.
  • Phagocytosis
    Type of endocytosis where cells ingest large particles or cells, often called 'cell eating.'
  • Pinocytosis
    Type of endocytosis where cells ingest extracellular fluid, often called 'cell drinking.'
  • Receptor-mediated Endocytosis
    Selective uptake of molecules into a cell via receptor binding and vesicle formation.
  • Hydrophobic
    Describes molecules that repel water and are typically nonpolar.
  • Hydrophilic
    Describes molecules that attract water and are typically polar.
  • Macromolecules
    Large complex molecules such as proteins, nucleic acids, and polysaccharides.