Chapter 7: Membrane Structure and Function Flashcards
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| 49153743 | diffusion | when a substance moves from an area of higher concentration to an area of lower concentration; caused by entrapy because nature wants stability | |
| 49153744 | osmosis | the diffusion of water through a selectively permeable membrane | |
| 49153745 | dialysis | the diffusion of small solutes through a selectively permeable membrane | |
| 49153746 | passive transport | diffusion or osmosis; the way a cell gets materials or excretes them by having them go from a high concentration to a low concentration; no ATP is necessary, energy comes from normal collisions; slow over large distances | |
| 49153747 | active transport | when a cell gets materials or excretes them by using its own energy, usually through ATP; going against natural tendencies | |
| 49153748 | hypertonic | describes a solution that has a greater concentration of total solute | |
| 49153749 | hypotonic | describes a solution that has a lesser concentration of total solute | |
| 49153750 | isotonic | describes solutions that have an equal concentration of total solutes | |
| 49153751 | turgor pressure | the pressure inside of a cell as a cell pushes itself against the cell wall | |
| 49153752 | plasmolysis | this happens when a cell shrinks inside its cell wall while the cell wall remains intact; concentration of water decreases, while solute concentration increases | |
| 49153753 | flaccid | this happens when water moves, but the amount within the cell is constant; no pressure builds | |
| 49153754 | cytolysis | this happens when a cell swells until pressure bursts it, resulting in cell death | |
| 49153755 | crenation | this happens when a cell shrinks and shrivels; can result in cell death if severe | |
| 49153756 | water potential | this states that water will always move from an area with high water potential to an area with low water potential | |
| 49153757 | solute potential | this measurement has a maximum value of 0; it decreases as the concentration of a solute increases | |
| 49153758 | pressure potential | this measurement has a minimum value of 0 (when the solution is open to the environment); it increases as pressure increases | |
| 49153759 | selective permeability | a property of a plasma membrane that allows some substances to cross more easily than others | |
| 49153760 | amphipathic | molecules are said to be this when it has regions that are both hydrophilic and hydrophobic | |
| 49153761 | fluid mosaic model | the currently accepted arrangement of membranes; it is a fluid structure with a "mosaic" of various proteins embedded in or attached to a double layer of phospholipids; proposed by Singer and Nicolson in 1972 | |
| 49153762 | integral proteins | the proteins of a membrane that penetrate the hydrophobic core of the lipid bilayer; hydrophobic regions consist of nonpolar amino acids, while hydrophilic regions are exposed to aqueous solution on either side of membrane | |
| 49153763 | transmembrane proteins | the proteins of a membrane that span the entire membrane | |
| 49153764 | peripheral proteins | the proteins of a membrane that are not embedded in the lipid bilayer; they are appendages loosely bound to the surface of the membrane, often exposed to parts of the integral proteins; attached by cytoskeleton on cytoplasmic side, and by fibers of ECM on extracellular side | |
| 49153765 | transport | the function of membrane proteins that allows travel through a hydrophilic channel, or by transport proteins, which shuttle molecules across the membrane by changing shape with the help of hydrolyzing ATP | |
| 49153766 | enzymatic activity | the function of membrane proteins that uses the exposure of proteins' active sites to adjacent solutions; metabolic processes progress to help substances pass | |
| 49153767 | signal transduction | the function of membrane proteins that allow proteins to have binding sites with specific shapes that fit chemical messengers; external messengers may cause a shape change in protein that relays a message to the inside of the cell, usually by binding to a cytoplasmic protein | |
| 49153768 | cell-cell recognition | the function of membrane proteins in which some glycoproteins serve as ID tags that are recognized by membrane proteins of other cells | |
| 49153769 | intercellular joining | the function of membrane proteins in which membrane proteins of adjacent cells hook together, as in gap junctions or tight junctions | |
| 49153770 | attachment to cytoskeleton and extracellular matrix | the function of membrane proteins in which microfilaments bond noncovalently to membrane proteins, maintaining cell shape and protein location; proteins bound to extracellular matrix molecules can coordinate extracellular and intracellular changes | |
| 49153771 | glycolipids | membrane carbohydrates that are covalently bonded to lipids | |
| 49153772 | glycoproteins | membrane carbohydrates that are covalently bonded to proteins | |
| 49153773 | first step | What step is this in moving a molecule from one side of the membrane to another? synthesis of membrane lipids and proteins in ER; carbohydrates are added to proteins, making them glycoproteins; the carbohydrate portion can be modified | |
| 49153774 | second step | What step is this in moving a molecule from one side of the membrane to another?inside Golgi, glycoproteins undergo further carbohydrate modification, and lipids acquire carbohydrates, becoming glycolipids | |
| 49153775 | third step | What step is this in moving a molecule from one side of the membrane to another? transmembrane proteins, membrane glycolipids, and secretory proteins are transported in vesicles to the plasma membrane | |
| 49153776 | fourth step | What step is this in moving a molecule from one side of the membrane to another? in plasma membrane, vesicles are fused, releasing secretory proteins from the cell; vesicle fusion positions carbohydrates on the outside of the plasma membrane; asymmetrical arrangement in the plasma membrane is determined by construction in the ER and Golgi | |
| 49153777 | transport protein | a membrane protein that is responsible for moving hydrophilic substances from one side to the other | |
| 49153778 | channel protein | a membrane protein, specifically a transport protein, that has a hydrophilic channel that certain molecules or atomic ions use as a tunnel | |
| 49153779 | aquaporin | a membrane protein, specifically a transport protein, that facilitates the passage of water through channel proteins | |
| 49153780 | carrier protein | a membrane protein, specifically a transport protein, that holds onto molecules and changes their shapes in a way that shuttles them across the membrane | |
| 50658221 | concentration gradient | the region along which the density of a substance decreases | |
| 50658222 | up | when a substance diffuses from an area of lower concentration to an area of higher concentration, it is moving ______ its concentration gradient | |
| 50658223 | down | when a substance diffuses from an area of higher concentration to an area of lower concentration, it is moving ________ its concentration gradient | |
| 50658224 | tonicity | the ability of a solution to cause a cell to gain or lose water; depends partly on concentration of nonpenetrating solutes relative to inside of cell | |
| 50658225 | osmoregulation | the control of water balance | |
| 50658226 | turgid | a cell with a cell wall that has a reasonable amount of pressure but is healthy | |
| 50658227 | flaccid | a cell with a cell wall that is in an isotonic solution that allows for a steady volume | |
| 50658228 | facilitated diffusion | passive diffusion that is aided by transport proteins, but that does not require cellular energy | |
| 50658229 | membrane potential | the voltage of a plasma membrane; ranges from -50 mV to -200 mV; the (-) signifies in which direction the substances move--(-) = outside of cell | |
| 50658230 | membrane potential | favors the passive transport of cations into the cell and anions out of the cell | |
| 50658231 | electrochemical gradient | the combination of forces that acts on membrane potential | |
| 50658232 | nonpolar | when ____________ entities hit the membrane, they dissolve through it and pass through the membrane and into the cell | |
| 50658233 | ionic | when ____________ entities hit the membrane, they accompany a protein in order to be dissolved, regardless of size | |
| 50658234 | small nonpolar | when ____________ entities hit the membrane, they pass through the membrane alone | |
| 50658235 | large polar | when ____________ entities hit the membrane, they are completely blocked from entering | |
| 50658236 | gated channel | a highly selective tunnel on a plasma membrane that can open or close depending on conformational changes; they are changed due to electrical disturbances, bonding of a specific ligand; allows a substance to diffuse | |
| 50658237 | electrogenic pump | a transport protein that generates voltage across a membrane, causing a net separation in charge | |
| 50658238 | proton pump | an electrogenic pump that works largely with H+ ions in plants, fungi, and bacteria | |
| 50658239 | cotransport | a mechanism through which a single ATP-powered pump that transports a specific solute can indirectly drive the active transport of several other solutes; substances that have been pumped across membrane can do work as they move back across the membrane by diffusion | |
| 50658240 | exocytosis | occurs when a cell secretes certain biological molecules by the fusion of vesicles with the plasma membrane | |
| 50658241 | endocytosis | occurs when a cell takes in biological molecules and particulate matter by forming new vesicles from the plasma membrane | |
| 50658242 | phagocytosis | a type of endocytosis in which the cell engulfs a particle by wrapping pseudopodia around it and packaging it within a membrane-enclosed sac that can be large enough to be considered a vacuole; particle is digested after vacuole fuses with lysosome | |
| 50658243 | pinocytosis | a type of endocytosis in which the cell "gulps" droplets of fluid into tiny vesicles; molecules dissolved in liquid are necessary for cell; nonspecific in substances it transports | |
| 50658244 | receptor-mediated | a type of endocytosis in which the cell acquires bulk quantities of specific substances, even though they may not be very concentrated in the extracellular fluid; receptor proteins are already clustered in regions of membrane called coated pits, which are lined on cytoplasmic side by fuzzy layer of coat proteins; when ligands bond to receptors, coated pits form a vesicle that contains ligand molecules | |
| 50658245 | ligand | any molecule that bonds specifically to a receptor site of another molecule |