Chapter 5 Vocab Flashcards
a property of biological membranes that allows them to regulate the passage of substances across them
selective permeability
having both a hydrophilic region and a hydrophobic region
amphipathic
the currently accepted model of cell membrane structure, which envisions the membrane as a mosaic of protein molecules drifting laterally in a fluid bilayer of phospholipids.
fluid mosaic model
a transmembrane protein with hydrophobic regions that extend into and often completely span the hydrophobic interior of the membrane and with hydrophilic regions in contact with the aqueous solution on one or both sides of the membrane (or lining the channel in the case of a channel protein).
integral protein
a protein loosely bound to surface of a membrane or to part of an integral protein and not embedded in the lipid bilayer
peripheral protein
a lipid with one or more covalently attached carbohydrates
glycolipid
a protein with one or more covalently attached carbohydrates
glycoprotein
a transmembrane protein that helps a certain substance or class of closely related substances to cross the membrane
transport protein
a channel protein in the plasma membrane of a plant, animal or microorganism cell that specifically facilitates osmosis, the diffusion of free water across the membrane
aquaporin
the spontaneous movement of a substance down its concentration or electrochemical gradient, from a region where it is more concentrated to a region where it is less concentrated.
diffusion
a region along which the density of a chemical substance increases or decreases.
concentration gradient
the diffusion of a substance across a biological membrane with no expenditure of energy
passive transport
the diffusion of free water across a selectively permeable membrane
osmosis
the ability of a solution surrounding a cell to cause that cell to gain or loose water.
tonicity
referring to a soultion that, when surrounding a cell, causes no net movement of water into or out of a cell
isotonic
referring to a solution that, when surrounding a cell, will cause the cell to lose water
hypertonic
referring to a solution that, when surrounding a cell, will cause the cell to take up water.
hypotonic
regulation of solute concentrations and water balance by a cell or organism
osmoregulation
swollen or distended, as in plant cells. (A walled cell becomes turgid if it has a lower water potential then its surroundings, resulting in entry of water.
turgid