Chapter 7: Membrane Structure and Function Flashcards
Movement of a substance across a membrane against its concentration or electrochemical gradient, meditated by a specific transport protein and requiring energy
Active Transport
Having a hydrophobic and hydrophilic region
Amphipathic
A channel protein in a cellular membrane that specifically facilitates osmosis, the diffusion of free water across the membrane
Aquaporin
A region along which the density of a chemical substance increases or decreases
Concentration Gradient
Coupling of the “downhill” diffusion of one substance to the “uphill” transport of another against its own gradient
Co-transport
Random thermal motion of particles of liquids, gases or solids. The net movement of a substance from a region where it is more concentrated to a region where it is less concentrated. (Electrochemical gradient)
Diffusion
Diffusion gradient of an ion, affected by both the concentration gradient of an ion across the membrane and the ion’s tendency to move relative to the membrane potential
Electrochemical Gradient
Active transport protein that generates a voltage across membrane while pumping ions
Electrogenic Pump
Cellular uptake of biological molecules and particular matter via formation of vesicles from the plasma membrane
Endocytosis
Cellular secretion of biological molecules by the fusion of vesicles containing them with the plasma membrane
Exocytosis
The passage of molecules or ion down their electrochemical gradient across a biological membrane with the assistance of specific transmembrane transport proteins, requiring no energy
Facilitated Diffusion
In a plant cell, lacking turgor in surroundings where there is a tendency for water to leave the cell. a walled cell if it has a higher water potential than its surrounding, resulting in loss of water
Flaccid
Accepted model of a 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 channel that opens or closes in response to a particular stimulus
Gated Channel
A lipid with one or more covalently attached carbohydrates
Glycolipid
A protein with one or more covalently attached carbohydrates
Glycoprotein
A solution, when surrounding a cell, will cause the cell to lose water
Hypertonic
A solution, surrounding a cell, will cause the cell to take up water
Hypotonic
A transmembrane protein channel that allows a specific ion to diffuse across the membrane down its concentration or electrochemical gradient
Ion Channel
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 aqueous solution on one or both sides of the membrane
Intergral Protein
A solution, when surrounding a cell, causes no net movement of water into or out of the cell
Isotonic
The difference in electrical charge across a cell’s plasma membrane due to the differential distribution of ions. Membrane potential affects the activity of excitable cells and the transmembrane movement of all charged substances
Membrane Potential
Regulation of solute concentrations and water balance by a cell or organism
Osmoregulation
The diffusion of free water across a selectively permeable membrane
Osmosis
The diffusion of a substance across a biological membrane with no expenditure of energy
Passive Transport
Protein loosely bound to the surface of a membrane or part of an integral protein and not embedded in the lipid bilayer
Peripheral Protein
A phenomenon in walled cells in which the cytoplasm shrivels and the plasma membrane pulls away from the cell wall; occurs when the cell loses water to a hypotonic environment
Plasmolysis
Active transport protein in membrane uses ATP to transport ion out of a cell against their concentration gradient, generating a membrane potential in the process
Proton Pump
A property of biological membranes that allows them to regulate the passage of substances across them
Selective Permeability
A transport protein in the plasma membrane of animal cells that actively transports sodium out of the cell and potassium into the cell
Sodium-Potassium Pump
Ability of a solution surrounding a cell to cause that cell to gain or lose water
Tonicity
A transmembrane protein that helps a certain substance or class of closely related substances to cross the membrane
Transport Protein
In plant cells, a walled cell becomes turgid if it has a lower water potential than its surrounding, resulting in entry of water
Turgid
