Membrance Structure and Function Flashcards

1284170440	Aquaporins	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.	0
1284170441	concentration gradient	A region along which the density of a chemical substance increases or decreases.	1
1284170442	cotransport	The coupling of the "downhill" diffusion of one substance to the "uphill" transport of another against its own concentration gradient.	2
1284170443	diffusion	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.	3
1284170444	electrochemical gradient	The diffusion gradient of an ion, which is affected by both the concentration difference of an ion across a membrane (a chemical force) and the ion's tendency to move relative to the membrane potential (an electrical force).	4
1284170445	endocytosis	Cellular uptake of biological molecules and particulate matter via formation of vesicles from the plasma membrane.	5
1284170446	exocytosis	The cellular secretion of biological molecules by the fusion of vesicles containing them with the plasma membrane.	6
1284170447	electrogenic pump	An active transport protein that generates voltage across a membrane while pumping ions.	7
1284170448	flaccid	Limp. Lacking turgor (stiffness or firmness), as in a plant cell in surroundings where there is a tendency for water to leave the cell. (A walled cell becomes flaccid if it has a higher water potential than its surroundings, resulting in the loss of water.)	8
1284170449	glycoprotein	A protein with one or more covalently attached carbohydrates.	9
1284170450	hypertonic	Referring to a solution that, when surrounding a cell, will cause the cell to lose water.	10
1284170451	hypotonic	Referring to a solution that, when surrounding a cell, will cause the cell to take up water.	11
1284170452	ion channel	A transmembrane protein channel that allows a specific ion to diffuse across the membrane down its concentration or electrochemical gradient.	12
1284170453	membrane potential	The difference in electrical charge (voltage) 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.	13
1284170454	osmoregulation	Regulation of solute concentrations and water balance by a cell or organism.	14
1284170455	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. I.e. elodea leaf in salt water.	15
1284170456	selective permeability	A property of biological membranes that allows them to regulate the passage of substances across them.	16
1284170457	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.	17
1284170458	turgid	Swollen or distended, as in plant cells. (A walled cell becomes turgid if it has a lower water potential than its surroundings, resulting in entry of water.)	18