Chapter 5 Membrane Structure and Function Vocab Flashcards
Having both a hydrophilic and hydrophobic region
Amphipathic Molecule
A channel protein in the plasma membrane of a plant, animal, or microorganism cell that specifically facilitates osmosis.
Aquaporin
A region along which the density of a chemical substance increases or decreases.
Concentration Gradient
The random thermal motion of particles of liquids, gases, or solids.
Diffusion
Cellular uptake of biological molecules and particulate matter via formation of vesicles from the plasma membrane.
Endocytosis
The cellular secretion of biological molecules by the fusion of vesicles containing them with the plasma membrane.
Exocytosis
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.
Facilitated Diffusion
Lacking tugor, as in a plant cell in surroundings where there is a tendency for water to leave the cell.
Flaccid
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 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 carbs
Glycoprotein
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 lose water.
Hypotonic
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
An atom or group of atoms that has gained or lost one or more electrons, thus acquiring a charge.
Ion channel
Referring to a solution that, when surrounding a cell, causes no net movement of water into or out of the cell.
Isotonic
A molecule that binds specifically to another molecule,, usually a larger one.
Ligand
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.
Membrane Potential
Regulation of solute concentrations and water balance by a cell or organism.
Osmoregulation
The diffusion of free water molecules across a selectively permeable membrane.
Osmosis
The diffusion of a substance across a biological membrane with no expenditure of energy.
Passive Transport
A protein loosely bound to the surface of a membrane or to a part of an integral protein and not embedded in the lipid bilayer.
Peripheral Protein
A type of endocytosis in which large particular substances or small organisms are taken up by a cell. It is carried out by some protists and by certain immune cells of animals (in mammals, mainly macrophages, neutrophils, and dendritic cells.)
Phagocytosis
A type of endocytosis in which the cell ingests extracellular fluid and its dissolved solutes.
Pinocytosis
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
The movement of specific molecules 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.
Receptor Mediated Endocytosis
A property of biological membrane 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
The 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
Swollen or distended, as in plant cells. (A walled cell becomes turgid if it has a lower water potential that its surroundings, resulting in entry of water.)
Turgid
