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Membrane Structure and Transport in General Biology

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이 집합의 용어 (21)

  • What are the major components of biological membranes?
    Biological membranes are mainly composed of phospholipids, proteins, and cholesterol arranged in a phospholipid bilayer.
  • What is the Fluid Mosaic Model?
    The Fluid Mosaic Model describes biological membranes as a fluid phospholipid bilayer with a mosaic of embedded proteins that move laterally.
  • What are the two main types of membrane proteins?
    1) Integral membrane proteins span the bilayer. 2) Peripheral membrane proteins are attached to the membrane surface.
  • Name some functions of membrane proteins.
    Membrane proteins function in transport, signal transduction, cell recognition, anchoring cytoskeleton, and enzymatic activity.
  • Define concentration gradient.
    A concentration gradient is the difference in concentration of a substance between two areas, driving diffusion from high to low concentration.
  • What is diffusion?
    Diffusion is the passive movement of molecules from an area of high concentration to an area of low concentration.
  • What does selectively permeable mean in biological membranes?
    Selectively permeable membranes allow some molecules to cross while blocking others, controlling molecular traffic.
  • Which molecules freely diffuse across membranes without protein facilitation?
    Small, nonpolar molecules like O2 and CO2 freely diffuse across membranes without protein help.
  • What are the two general types of molecular transport across membranes?
    1) Passive transport moves molecules down their concentration gradient without energy. 2) Active transport moves molecules against the gradient using energy.
  • What is the difference between passive and active transport?
    Passive transport requires no energy and moves substances down gradients; active transport requires energy (usually ATP) to move substances against gradients.
  • What are uniporters, symporters, and antiporters?
    Uniporters transport one molecule in one direction; symporters transport two molecules in the same direction; antiporters transport two molecules in opposite directions.
  • Define osmosis.
    Osmosis is the passive diffusion of water across a semi-permeable membrane from a region of low solute concentration to high solute concentration.
  • What is the difference between hypotonic, isotonic, and hypertonic solutions?
    Hypotonic solutions have lower solute concentration; isotonic have equal; hypertonic have higher solute concentration compared to the cell.
  • What happens to cells in hypotonic environments?
    Water enters cells causing them to swell and possibly lyse; plant cells become turgid due to increased turgor pressure.
  • What is the difference between simple diffusion and facilitated diffusion?
    Simple diffusion is direct movement of small uncharged molecules; facilitated diffusion requires transport proteins to move charged or large molecules.
  • Name two types of transport proteins involved in facilitated diffusion.
    1) Channels/porins form pores for molecules. 2) Carriers/transporters undergo conformational changes to move molecules.
  • What is primary active transport?
    Primary active transport uses energy from ATP hydrolysis to move molecules against their concentration gradient.
  • Describe the sodium-potassium pump.
    It is a primary active antiporter that moves 3 Na+ ions out and 2 K+ ions into the cell using ATP energy.
  • What is secondary active transport?
    Secondary active transport uses the concentration gradient established by primary active transport to drive movement of other molecules.
  • What are endocytosis and exocytosis?
    Endocytosis is the process of engulfing large molecules into the cell via vesicles; exocytosis is vesicle fusion with the membrane to export molecules.
  • Name the three main types of endocytosis.
    1) Phagocytosis (cell eating), 2) Pinocytosis (cell drinking), 3) Receptor-mediated endocytosis (selective uptake via receptors).