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General Biology: Cell Membranes and Transport

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Termini in questo insieme (17)

  • Structural components of membranes
    Membranes are mainly composed of a phospholipid bilayer, proteins, cholesterol, and carbohydrates.
  • Functional benefits of membrane-bound compartments
    They allow specialization of cellular processes and maintain distinct environments for different biochemical reactions.
  • Roles of proteins in membranes
    Membrane proteins function in transport, signal transduction, cell recognition, and structural support.
  • Membrane permeability for polar vs nonpolar molecules
    Nonpolar molecules pass easily through membranes, while polar molecules require specific transport proteins.
  • Movement of molecules from high to low concentration
    This passive movement is called diffusion and occurs down the concentration gradient.
  • Diffusion vs osmosis
    Diffusion is the movement of solutes; osmosis is the diffusion of water across a selectively permeable membrane.
  • Hypotonic solution effect on animal cells
    Water enters the cell, causing it to swell and possibly burst (lysis).
  • Isotonic solution effect on cells
    Water moves in and out at equal rates, so cell size remains stable.
  • Hypertonic solution effect on plant cells
    Water leaves the cell, causing the cell membrane to pull away from the cell wall (plasmolysis).
  • Active transport across membranes
    Active transport uses energy to move substances against their concentration gradient.
  • Energy requirements: passive vs active transport
    Passive transport requires no energy; active transport requires ATP or another energy source.
  • Active transport of large vs small substances
    Small molecules use protein pumps; large substances use vesicle-mediated processes like endocytosis.
  • Role of the extracellular matrix (ECM) in animal cells
    The ECM provides structural support and influences cell behavior and communication.
  • Adhesion junctions in animal cells
    They connect the cytoskeletons of adjacent cells, providing mechanical stability.
  • Tight junctions in animal cells
    They create a seal that prevents leakage of extracellular fluid between cells.
  • Gap junctions in animal cells
    They allow direct communication by permitting the passage of ions and small molecules.
  • Cell-to-cell junctions in plants vs animals
    Plants have plasmodesmata for communication; animals have adhesion, tight, and gap junctions.