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Membrane Structure and Transport in General Biology

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Termini in questo insieme (20)

  • Fluid mosaic model
    Membranes are composed of a fluid bilayer of phospholipids with proteins embedded, forming a mosaic that carries out various functions.
  • Phospholipid bilayer structure
    Phospholipids have hydrophilic heads facing water on both sides and hydrophobic tails inside, forming a bilayer.
  • Amphipathic molecules
    Molecules like phospholipids and membrane proteins have both hydrophilic and hydrophobic regions.
  • Membrane fluidity factors
    Membrane fluidity is influenced by lipid composition, temperature, and cholesterol content.
  • Effect of unsaturated vs saturated fatty acids on membrane fluidity
    Unsaturated fatty acid tails increase fluidity by preventing tight packing; saturated tails decrease fluidity by packing tightly.
  • Role of cholesterol in membrane fluidity
    Cholesterol reduces fluidity at moderate temperatures by restraining phospholipid movement and prevents solidification at low temperatures by disrupting packing.
  • Peripheral vs integral membrane proteins
    Peripheral proteins are bound to membrane surfaces; integral proteins penetrate the hydrophobic core, with transmembrane proteins spanning the membrane.
  • Functions of membrane proteins
    Membrane proteins function in transport, enzymatic activity, signal transduction, cell-cell recognition, intercellular joining, and attachment to cytoskeleton and ECM.
  • Selective permeability of membranes
    Membranes allow some substances to cross more easily than others, mainly due to the lipid bilayer and specific transport proteins.
  • Passive transport
    Movement of molecules down their concentration gradient without energy input.
  • Active transport
    Movement of molecules against their concentration gradient requiring energy, usually from ATP.
  • Transport proteins: channel vs carrier
    Channel proteins provide hydrophilic tunnels; carrier proteins bind and change shape to shuttle molecules across membranes.
  • Aquaporins
    Special channel proteins that facilitate rapid water transport across membranes.
  • Osmosis
    Diffusion of free water molecules across a selectively permeable membrane from higher to lower free water concentration.
  • Tonicity
    The ability of a solution to cause a cell to gain or lose water based on solute concentration relative to the cell.
  • Isotonic solution
    Solution with solute concentration equal to that inside the cell; no net water movement.
  • Hypertonic solution
    Solution with higher solute concentration than the cell; water leaves the cell causing it to shrivel.
  • Hypotonic solution
    Solution with lower solute concentration than the cell; water enters the cell causing it to swell or burst.
  • Bulk transport
    Movement of large molecules via vesicles through exocytosis (out) or endocytosis (in).
  • Types of endocytosis
    Phagocytosis (cell eating), pinocytosis (cell drinking), and receptor-mediated endocytosis.