Chapter 7 Flashcards
The coupling of the “downhill” diffusion of one substance to the “uphill” transport of another against its own concentration gradient.
Cotransport
A molecule that binds specifically to another molecule, usually a larger one.
Ligands
A type of endocytosis in which large particulate substances are taken up by a cell.
Phagocytosis
The cellular secretion of biological molecules by the fusion of vesicles containing them with the plasma membrane.
Exocytosis
An ion transport protein that generates voltage across a membrane.
Electrogenic Pump
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
A transmembrane protein channel that allows a specific ion to flow across the membrane down its concentration gradient.
Ion Channels
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.
Plasmolysis
Swollen or distended, as in plant cells. (A walled cell becomes _____ if it has a greater solute concentration that its surroundings, resulting in the entry of water.)
Turgid
Referring to a solution that, when surrounding a cell, will cause the cell to take up water.
Hypotonic
Referring to a solution that, when surrounding a cell, has no effect on the passage of water into or out of the cell.
Isotonic
The diffusion of a substance across a biological membrane with no expenditure of energy.
Passive Transport
The spontaneous movement of a substance down its concentration gradient, from a region where it is more concentrated to a region where it is less concentrated.
Diffusion
A transmembrane protein that helps a certain substance or class of closely related substances to cross the membrane.
Transport Proteins
A lipid with covalently attached carbohydrates.
Glycolipids
Typically 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 either side of the membrane (or lining the channel in the case of a channel protein).
Integral Proteins
Having both a hydrophilic region and a hydrophobic region.
Amphipathic
A property of biological membranes that allows them to regulate the passage of substances.
Selective Permeability
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 protein loosely bound to the surface of a membrane or part of an integral protein and not embedded in the lipid bilayer.
Peripheral Proteins
A protein with one or more carbohydrates covalently attached to it.
Glycoproteins
A channel protein in the plasma membrane of a plant, animal, or microorganism cell that specifically facilitates osmosis, the diffusion of water across the membrane.
Aquaporins
A region along which the density of a chemical substance increases or decreases.
Concentration Gradient
The diffusion of water across a selectively permeable membrane.
Osmosis
Referring to a solution that, when surrounding a cell, will cause the cell to lose water.
Hypertonic
Regulation of solute concentrations and water balance by a cell or organism.
Osmoregulation
Limp. Lacking in stiffness or firmness, as in a plant cell in surroundings where there is no tendency for water to enter the cell.
Flaccid
The spontaneous passage of molecules or ions across a biological membrane with the assistance of specific transmembrane transport proteins.
Facilitated Diffusion
The movement of a substance across a cell membrane, with an expenditure of energy, against its concentration or electrochemical gradient; mediated by specific transport proteins.
Active Transport
The diffusion gradient of an ion, which is affected by both the concentration difference of the ion across a membrane (a chemical force) and the ion’s tendency to move relative to the membrane potent ion (an electrical force).
Electrochemical Gradient
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.
Proton Pump
Cellular uptake of biological molecules and particulate matter via formation of new vesicles from the plasma membrane.
Endocytosis
A type of endocytosis in which the cell ingests extracellular fluid and its dissolved solutes.
Pinocytosis
A transmembrane protein channel that opens or closes in response to a particular stimulus.
Gated Channels
