Chapter 5 (Membrane Structure And Funciton) Vocab Quiz Flashcards
Amphipathic molecule
A molecule having both hydrophilic and hydrophobic regions
Aquaporin
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
COncentration gradient
A region along which the density of a chemical substance increases or decreases
Diffusion
The random thermal motion of particles of liquids, gases or solids. In the resented of a concentration or electrochemical gradient, diffusion results in the net movement of a substance from a region where it is less concentrated.
Endocytosis
Cellular uptake of biological molecules and particulate matter via formation of vesicles from the plasma membrane
Exocytosis
The cellular secretion of biological membranes by the fusion of vesicles containing them with the plasma membrane
Facilitated diffusion
The passage of molecules or ions down their electrochemical gradient across a biological membrane with the assistance of specific transmembrane transport proteins, requiring no energy expenditure.
Flaccid
Limp, lacking turbot, as in a plant cell in surroundings where there is a tendency for water to leave the cell
Fluid mosaic model
The currently accepted model of cell membrane structure, which envisions the membrane as a mosaic of protein molecules drifting laterally in a fluid belayer of phospholipids.
Gated channel
A tranembrane protein channel that opens or closes in response to a particular stimulus
Glycolipid
A lipid with one or more covalently attached carbohydrates
Glycoprotein
A protein with one or more covalently attached carbohydrates
Hypertonic
Referring to a solution that, when surrounding a cell will cause the cell to lose water
Hypotonic
Referring to a solution that, when surrounding a cell, will cause the cell to take up water
Integral protein
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 Aquaeous solution on one or both sides of the membrane
Ion channel
A transmembrane protein channel that allows a specific ion to diffuse across the membrane down its concentration or electrochemical gradient
Isotonic
Referring to a solution that, when surrounding a cell, causes no net movement of water into or out of the cell
Ligand
A molecule that binds specifically to another molecule, usually a larger one
Membrane potential;
The difference in electrical charge across a cells plasma membrane die to the differential distribution of ions membrane potential affects the activity of excitable cells and the transmembrane movement of all charged substances
Osmoregulation
Regulation of solute concentrations and water balance by a cell or organisms
Osmosis
The diffusion of free water molecules across a selectively permeable membrane
Passive transport
The dffusion of a substance across a biological membrane with no expenditure of energy
Peripheral protein
A protein loosely bound to the surface of a membrane or to part of an intergalactic protein and not embedded in the lipid belayer
Phagocytosis
A type of endocytosis in which large particulate substances or small organisms are taken up by a cell. It is carried out by some protists and by certain immune cells of animals
Pinocytosis
A type of endocytosis in which the cell ingests extracellular fluid and its dissolved salutes
Plasmolysis
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 hypertonic environment
Proton pump
An active transport protein in a cell membrane that uses ATP to transport hydrogen ions out of a cell against their concentration gradient, generating a membrane potential in the process
Receptor mediated endocytosis
The movement of specific olecules into a cell by the inward budding of vesicles containing proteins with receptor sites specific to the molecules being taken in, enables a cell to acquire bulk quantities of specific substances
Selective permeability
A property of biological membranes that allows them to regulate the passage of substances across them
Sodium potassium pump
A transport protein in the plasma membrane of animal cells that actively transports sodium out of the cell and potassium into the cell
Tonicity
The ability of a solution surrounding a cell to cause that cell to gain or lose water
Transport protein
A transmembrane protien that helps a certain substance or class of closely related substances to cross the membrane
Turgid
Swollen or distended as in plant cells
