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General Biology: Membrane Transport and Cell Signaling

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Termini in questo insieme (40)

  • Phospholipids
    Molecules with a hydrophilic head and two hydrophobic tails that form the basic structure of cell membranes.
  • Bilayer
    Two layers of phospholipids arranged tail-to-tail forming the fundamental structure of membranes.
  • Fluid Mosaic
    Model describing the membrane as a fluid combination of phospholipids, cholesterol, and proteins.
  • Selective permeability
    Property of membranes allowing some substances to cross more easily than others.
  • Homeostasis
    The maintenance of stable internal conditions despite external changes.
  • Electro-chemical gradient
    Combined effect of chemical and electrical forces that drive ion movement across membranes.
  • Amphipathic
    Molecules having both hydrophilic and hydrophobic regions, like phospholipids.
  • Saturated vs Unsaturated fatty acids
    Saturated fatty acids have no double bonds and pack tightly; unsaturated have one or more double bonds causing kinks.
  • Cholesterol in membranes
    A lipid that stabilizes membrane fluidity by preventing tight packing of phospholipids.
  • Membrane proteins / Integral proteins
    Proteins embedded in the membrane that assist in transport, signaling, and structural support.
  • Major functions of membrane proteins
    Transport, enzymatic activity, signal transduction, cell-cell recognition, intercellular joining, and attachment to cytoskeleton.
  • Glycoproteins and glycolipids
    Membrane molecules with carbohydrate chains important for cell recognition and signaling.
  • Gradient
    A difference in concentration or charge that drives movement of substances across membranes.
  • Osmosis
    Diffusion of water across a selectively permeable membrane from low to high solute concentration.
  • Osmoregulation
    Control of water balance within a cell or organism to maintain homeostasis.
  • Tonicity: hypertonic, hypotonic
    Hypertonic solutions cause cells to lose water; hypotonic solutions cause cells to gain water.
  • Diffusion
    Passive movement of molecules from high to low concentration.
  • Passive vs active transport
    Passive transport requires no energy; active transport requires energy to move substances against gradients.
  • Channel proteins, pores, carrier proteins, gated ion channels
    Membrane proteins that facilitate selective transport of ions and molecules.
  • Electrogenic pumps
    Transport proteins that generate voltage across membranes by moving ions.
  • Sodium-potassium pump
    An electrogenic pump that moves 3 Na+ out and 2 K+ into the cell using ATP.
  • Proton pump
    An electrogenic pump that moves H+ ions across membranes to create a proton gradient.
  • Membrane potential
    Voltage difference across a membrane due to ion distribution.
  • Cotransport
    Coupled transport of two substances across a membrane by one protein.
  • Uniporter, symporter, antiporter
    Uniporter transports one molecule; symporter transports two in the same direction; antiporter transports two in opposite directions.
  • Bulk transport: endocytosis and exocytosis
    Processes that move large molecules or particles into (endocytosis) or out of (exocytosis) the cell.
  • Phagocytosis and pinocytosis
    Phagocytosis engulfs large particles; pinocytosis takes in fluids and dissolved substances.
  • Intercellular vs intracellular signaling
    Intercellular signaling occurs between cells; intracellular signaling occurs within a cell.
  • Autocrine signaling
    Cells respond to signals they themselves release.
  • Paracrine signaling
    Signals affect nearby cells.
  • Synaptic signaling
    Neurons release neurotransmitters to signal adjacent cells across synapses.
  • Endocrine signaling
    Hormones travel through the bloodstream to distant target cells.
  • Signal transduction
    Process by which a signal is converted into a cellular response.
  • Ligands and receptors
    Ligands are signaling molecules that bind to specific receptors to initiate signaling.
  • G protein-coupled receptors
    Membrane receptors that activate G proteins to relay signals inside the cell.
  • Intracellular receptors
    Receptors located inside the cell that bind ligands that cross the membrane.
  • Signal amplification
    Process where a small signal triggers a large cellular response.
  • Phosphorylation, kinase, phosphatase
    Kinases add phosphate groups to proteins; phosphatases remove them, regulating activity.
  • Second messengers
    Small molecules like cyclic AMP that relay signals inside the cell.
  • Cyclic AMP
    A common second messenger that activates protein kinase A to propagate signals.