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Ch.5 Cell Membrane Structure & Transport Processes

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Terms in this set (21)

  • Phospholipid structure
    Phospholipids have a hydrophilic phosphate head and two hydrophobic fatty acid tails, forming the basic structure of cell membranes.
  • Phospholipid bilayer
    Cell membranes consist of a phospholipid bilayer with hydrophilic heads facing outward and hydrophobic tails facing inward.
  • Fluid mosaic model
    Describes the plasma membrane as a fluid combination of phospholipids, cholesterol, and proteins that move laterally.
  • Integral membrane proteins
    Proteins embedded within the membrane with hydrophilic and hydrophobic regions, often forming channels or carriers.
  • Peripheral membrane proteins
    Proteins attached to the membrane surface, not embedded, often involved in signaling or structural support.
  • Cholesterol role in membranes
    Cholesterol in animal membranes provides flexibility and stability by preventing tight packing of phospholipids.
  • Selective permeability
    The plasma membrane allows some molecules to pass while blocking others based on size, charge, and polarity.
  • Diffusion
    Passive movement of molecules from high to low concentration without energy input.
  • Osmosis
    The diffusion of water across a selectively permeable membrane from low to high solute concentration.
  • Isotonic solution
    A solution with equal solute concentration compared to the cell, causing no net water movement.
  • Hypertonic solution
    A solution with higher solute concentration than the cell, causing water to leave the cell and shrink.
  • Hypotonic solution
    A solution with lower solute concentration than the cell, causing water to enter the cell and swell.
  • Facilitated diffusion
    Passive transport of polar or charged molecules across membranes via specific transport proteins.
  • Active transport
    Energy-requiring process where molecules move against their concentration gradient using transport proteins and ATP.
  • Exocytosis
    Process where cells export large molecules by vesicles fusing with the plasma membrane.
  • Endocytosis
    Process where cells engulf large molecules by forming vesicles from the plasma membrane.
  • Phagocytosis
    A type of endocytosis where the cell engulfs large particles or cells ('cell eating').
  • Receptor-mediated endocytosis
    Selective uptake of molecules using receptors on the cell surface that trigger vesicle formation.
  • Concentration gradient
    Difference in molecule concentration across a space or membrane driving diffusion.
  • Role of transport proteins
    Transport proteins assist in moving substances that cannot diffuse freely through the lipid bilayer.
  • Effect of tonicity on plant cells
    In hypotonic solutions, plant cells become turgid; in hypertonic, they plasmolyze; isotonic causes flaccidity.