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Membrane Structure and Function

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이 집합의 용어 (20)

  • Fluid Mosaic Model
    The membrane is a mosaic of protein molecules bobbing in a fluid bilayer of phospholipids, allowing lateral movement of proteins and lipids.
  • Phospholipid Bilayer
    A double layer of phospholipids with hydrophilic heads facing outward and hydrophobic tails inward, forming the basic structure of membranes.
  • Amphipathic Molecules
    Molecules that have both hydrophilic (water-attracting) and hydrophobic (water-repelling) regions, like phospholipids.
  • Membrane Fluidity Factors
    Fluidity depends on temperature, saturation of fatty acid tails, and cholesterol content; unsaturated tails increase fluidity, cholesterol stabilizes it.
  • Integral vs Peripheral Proteins
    Integral proteins penetrate the hydrophobic core of the bilayer; peripheral proteins are loosely bound to the membrane surface.
  • Functions of Membrane Proteins
    Include transport, enzymatic activity, signal transduction, cell-cell recognition, intercellular joining, and attachment to cytoskeleton and ECM.
  • Selective Permeability
    Membranes allow some substances to cross more easily than others, typically nonpolar molecules cross freely, polar molecules require transport proteins.
  • Diffusion
    The movement of molecules from higher to lower concentration down their concentration gradient without energy input.
  • Osmosis
    Diffusion of water across a selectively permeable membrane from lower to higher solute concentration.
  • Facilitated Diffusion
    Passive transport of molecules across membranes via specific transport proteins, moving solutes down their concentration gradient.
  • Active Transport
    Energy-requiring process that moves molecules against their concentration gradient using transport proteins and ATP.
  • Sodium-Potassium Pump
    An active transport protein that pumps Na+ out and K+ into animal cells, maintaining membrane potential.
  • Cotransport
    Active transport driven by the concentration gradient of another molecule, e.g., glucose uptake coupled with Na+ movement.
  • Exocytosis
    Bulk transport process where large molecules are secreted out of the cell via vesicles fusing with the plasma membrane.
  • Endocytosis
    Bulk transport process where cells take in large molecules by forming vesicles from the plasma membrane.
  • Phagocytosis
    A type of endocytosis where large particles are engulfed by membrane extensions called pseudopodia, forming a phagosome.
  • Pinocytosis
    A type of endocytosis involving nonspecific uptake of extracellular fluid and solutes into small vesicles.
  • Receptor-Mediated Endocytosis
    Selective uptake of molecules using membrane receptors that cluster in coated pits forming vesicles.
  • Membrane Protein Mobility
    Proteins can move laterally within the membrane but some are immobilized by attachments to the cytoskeleton or ECM.
  • Role of Cholesterol in Membranes
    Cholesterol modulates membrane fluidity by reducing it at high temperatures and preventing solidification at low temperatures.