Chapter 5.txt

  1. active transport
    Pumping of a specific solute across a cell membrane against its concentration gradient, through the interior of a transport protein. Requires energy input, as from ATP.
  2. adhesion proteins
    Of multicelled species, a plasma membrane protein that helps cells stick together in tissues and to extracellular matrixes such as basement membrane.
  3. biofilms
    Large microbial populations that anchored themselves to epithelium, rocks, or other surfaces by their own secretions.
  4. bulk flow
    The mass movement of one or more substances in the same direction, most often in response to pressure.
  5. calcium pump
    Active transport protein; pumps calcium ions across a cell membrane against their concentration gradient.
  6. communication proteins
    A membrane protein that helps form an open channel between the cytoplasm of adjoining cells.
  7. concentration gradient
    Difference in the number of molecules or ions of any one substance between two adjoining regions.
  8. diffusion
    Net movement of like ions or molecules from a region where they are most concentrated to an adjoining region where they are less concentrated; they move down their concentration gradient.
  9. electric gradient
    A difference in electric charge between adjoining regions.
  10. endocytosis
    Cell uptake of substances by forming vesicles from patches of plasma membrane. Three modes are receptor-mediated endocytosis, phagocytosis, and the bulk transport of extracellular fluid.
  11. exocytosis
    Fusion of a cytoplasmic vesicle with the plasma membrane; as it becomes part of the membrane, its contents are released to extracellular fluid.
  12. fluid mosaic model
    A cell membrane has a mixed composition (mosaic) of lipids and proteins, the interactions and motions of which impart fluidity to it.
  13. hydrostatic pressure
    Pressure exerted by a volume of fluid against a cell wall, membrane, or some other structure that contains it; also called turgor pressure.
  14. hypertonic solution
    Of two fluids, the one with the higher solute concentration.
  15. hypotonic solution
    Of two fluids, the one with the lower solute concentration.
  16. isotonic solution
    Any fluid having the same solute concentration as another fluid to which it is being compared.
  17. lipid bilayer
    Structural basis of all cell membranes; mainly phospholipids arranged tail-to-tail in two layers, with hydrophilic heads of one dissolved in cytoplasmic fluid and heads of the other in extracellular fluid.
  18. osmosis
    Diffusion of water across a selectively permeable membrane from a region where the water concentration is higher to a region where it is lower.
  19. osmotic pressure
    The amount of pressure which, when applied to a hypertonic fluid, will stop osmosis from occurring across a semipermeable membrane.
  20. passive transport
    Diffusion of a solute across a cell membrane, through the interior of a transport protein.
  21. phagocytosis
    [Gk. phagein, to eat] �Cell eating,� a common endocytic pathway by which various cells engulf food bits, microbes, and cellular debris.
  22. phospholipid
    A lipid with a phosphate group in its hydrophilic head. The main constituent of cell membranes.
  23. pressure gradient
    Difference in pressure between two adjoining regions.
  24. recognition proteins
    One of a class of glycoproteins or glycolipids that project above the plasma membrane and that identify a cell as nonself (foreign) or self (belonging to one�s own body tissue).
  25. selective permeability
    Built-in capacity of a cell membrane to prevent or allow specific substances from crossing it at certain times, in certain amounts.
  26. sodium-potassium pump
    Cotransporter that, when energized, actively transports sodium out of a cell and helps potassium passively diffuse into it at the same time.
  27. tonicity
    Relative solute concentrations of two fluids.
  28. transport proteins
    Membrane protein that passively or actively assists specific ions or molecules into or out of a cell. The solutes move through the protein�s interior.
Card Set
Chapter 5.txt
Chapter 5