Chapter 5 Vocab Flashcards
the selectively permeable surface membrane that encloses the cell contents and through which all materials entering or leaving the cell must pass
Plasma Membrane
a molecule containing both hydrophobic and hydrophilic regions
Amphipathic Molecules
the currently accepted model of the plasma membrane and other cell membranes, in which protein molecules “float” in a fluid phospholipid bilayer
Fluid Mosaic Model
a protein that is tightly associated with the lipid bilayer of a biological membrane; a transmembrane integral protein spans the bilayer
Integral Membrane Proteins
an integral membrane protein that spans the lipid bilayer
Transmembrane Proteins
a protein associated with one of the surfaces of a biological membrane
Peripheral Membrane Proteins
a protein with covalently attached carbohydrates
Glycoproteins
a membrane that allows some substances to cross it more easily than others. Biological membranes are generally permeable to water but restrict the passage of many solutes
Selectively Permeable Membranes
any form of transport across a membrane that uses a membrane-bound transport protein with a binding site for a specific substance; includes both facilitated diffusion and carrier-mediated active transport
Carrier-Mediated Transport
ATP-binding cassette transporters; use ATP energy to transport certain ions, sugars, and polypeptides across cell membranes
ABC Transporters
one of a family of transport proteins located in the plasma membrane that facilitate the rapid movement of water molecules into or out of cells
Aquaporins
the net movement of particles (atoms, molecules, or ions) from a region of higher concentration to a region of lower concentration
Diffusion
a difference in the concentration of a substance from one point to another, as for example, across a cell membrane
Concentration Gradient
the condition of a chemical reaction when the rate of change in one direction is exactly the same as the rate of change in the opposite direction, and the difference in free energy between reactants and products is zero
Dynamic Equilibrium
small, non-polar, solute molecules move directly through the membrane down the concentration gradient
Simple Diffusion
a term applied to solutions that have identical concentrations of solute molecules and hence the same osmotic pressure
Isotonic
the net movement of water by diffusion through a selectively permeable membrane from a higher concentration of water to a lower concentration of water
Osmosis
the pressure that must be exerted on the hypertonic side of a selectively permeable membrane to prevent diffusion of water from the side containing pure water
Osmotic Pressure
a term referring to a solution having an osmotic pressure greater than that of the solution with which it is compared
Hypertonic
a term of referring to a solution having an osmotic pressure less than that of the solution with which it is compared
Hypotonic
hydrostatic pressure that develops within a walled cell and presses outward against the plasma membrane
Turgor Pressure
the shrinkage of cytoplasm and the pulling away of the plasma membrane from the cell wall when a plant cell loses water, usually in a hypertonic environment
Plasmolysis
the passive transport of ions or molecules by a specific carrier protein in a membrane
Facilitated Diffusion
transport of a substance across a membrane that does not rely on the potential energy of a concentration gradient for the substance being transported and therefore requires an additional energy source
Active Transport
