Chapter 5 Flashcards
Aquaporin
A channel protein in the plasma membrane of a plant, animal, or microorganism cell that specifically facilitates osmosis
Amphipathic
Having both a hydrophobic and hydrophilic region
Active transport
The movement of a substance across a cell membrane against its concentration gradient, mediated by transport proteins that use energy.
Concentration gradient
A region along which density of a chemical substance increases or decreases
Cotransport
The coupling of the downhill diffusion of one substance to the uphill transport of another against its own concentration gradient
Diffusion
The random thermal motion of particles of liquids, gases, or solids. In the presence of a concentration gradient, substances moves from a region of more concentration to lower concentration
Electrochemical gradient
The diffusion gradient of an ion, which is affected by both the concentration diffrence of an ion across a membrane and the ions tendency to move relative to the membrane potential
Electrogenic pump
An active transport protien that generates voltage across a membrane while pumping ions
Endocytosis
Cellular uptake of biological molecules and particles of matter via formation of vesicles from the plasma membrane
Exocytosis
The cellular secretion of biological molecules by the fusion of vesicles containing them with the plasma membrane
Fluid mosaic model
The currently accepted model of the plasma membrane structure, which envisions the membrane as a mosaic of protien molecules drifting latterly in a fluid bilayer of phospholipids
Facilitated diffusion
The passage of molecules or ions down their electrochemical gradient across a biological membrane with the assistance of specific transport protiens, requiring no energy expenditure
Glycolipids
A lipid with one or more covalently attached carbohydrates
Glycoproteins
A protien with one or more covalent attached carbohydrates
Gated channels
A transmembrane protien channel that poems or closes in response to a particular stimulus
G protien
A gtp-binding protein that relays signals from a plasma membrane signal receptor
G protein coupled receptor
A signal receptor protien in the plasma membrane that responds to the binding of a signaling molecule by activating a g protien
Hypertonic
Referring to a solution that, when surround ding a cell, will cause the cell to loose water
Hypotonic
Referring to a solution that, when surrounding a cell, will cause the cell to take up water
Integral protien
a transmembrane protien with hydrophobic region that extends into and often completely spans the hydrophobic interior of the membrane and with hydrophilic regions in contact with the aqueous solution on one or both sides of the membrane
Isotonic
Referring to a solution, that, when surrounding s cell, causes net movement of water out of the cell
Ion channel
A transmembrane protien channel that allows a specific ion to diffuse across the membrane down its concentration and electrochemical gradient
Ligand
A molecule that binds specifically to another molecule, usually a larger one
Ligand gated ion channel
A transmembrane protien containing a Pore that opens of closes as it changes shape in response to a signaling molecule, allowing or blocking the flow of specific ions
Membrane potential
The difference in electrical charge across a cells 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.