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chp3
chp3 plasma membrane
| Term | Definition |
|---|---|
| cells | structural units of all living things. |
| generalized cell | (composite cell) regardless of differences all cells have the same basic parts and common functions. |
| interstitial fluid | the fluid between cells, an extracellular fluid |
| extracellular fluid | substances contributing to body mass that are found outside cells. |
| fluid mosaic model | is a depiction of the plasma membrane composed of double layer of lipid molecules with protein molecules dispersed in it. |
| glycolipids | lipids with attached sugar groups. |
| integral proteins | firmly inserted in the lipid layer of plasma membrane. |
| peripheral proteins | attach loosely to integral proteins. |
| glycocalyx | sugar covering, fuzzy, sticky, carbohydrate rich at the cell surface. consist of glycoproteins and gylcolipids. |
| possible functions of membrane proteins | transport, receptors for signal transduction, enzymatic activity, attachment to the cytoskeleton and extracellular matrix, intercellular joining, cell-cell recognition. |
| tight junction | when a series of integral proteins in plasma membrane, adjacent to each other, fuse together creating a seal around the cells that is impermeable. |
| Desmosomes | anchoring, mechanical couplings scattered like rivets along sides of adjacent cells to prevent separation. acts like velcro and internal tension reducing fiber. |
| gap junction | communicating spot between adjacent cells, allows ions and small molecules to pass are particularly important for communication in heart cells and embryonic cells. |
| passive processes | substances cross membrane without any energy input form cell. |
| active processes | cell provides metabolic energy (usually ATP) needed to move substances across membrane. |
| simple diffusion | nonpolar and lipid- soluble substances diffuse directly through the lipid bilayer. |
| facilitated diffusion | a passive transport process the substance binds to protein carriers and is carried across or moves through water-filled channels to get into the cell. |
| osmosis | the diffusion of a solvent(usually water) through a selectively permeable membrane. means pushing. |
| osmolarity | the total concentration of all solute particles in a solution is the solutions --------. |
| hydrostatic pressure | the back pressure exerted by water against the membrane. |
| osmotic pressure | the tendency of water to move into the cell by osmosis. |
| tonicity | the ability of a solution to change the shape or tone of cells by altering the cells internal water volume . tono =tension |
| isotonic solutions | cells retain their normal size and shape because there is the same solute/water concentration inside cell and out. water moves in and out. |
| hypertonic solutions | cells lose water by osmosis and shrink because has a higher concentration of non-penetrating solutes than in cell. |
| hypotonic solutions | cells take on water by osmosis until they become bloated and lyse (burst). has lower concentration of non- penetrating solutes than in the cell. |
| primary active transport | A type of active transport in which the energy needed to drive the transport process is provided directly by hydrolysis of atp. |
| sodium potassium pump | A primary active transport system that simultaneously drives Na+ out of the cell against a steep gradient and pumpsK+ back in. also called Na+-K+ ATPase |
| active transport | 1 membrane transport process for which ATP is directly or indirectly required, e.g. solute pumping and endocytosis. 2 also specifically refers to solute pumping. |
| solute pump | enzyme like protein carrier that mediates active transport of solutes such as amino acids and ions uphill against their concentration gradients. |
| secondary active transport | A type of active transport in which energy needed to drive process is provided by electrochemical gradient of another molecule(which moves downhill at same time another moves up against its gradient). also called cotransport, symport, antiport |
| electrochemical gradients | The combined difference in concentration and charge; influences the distribution and direction of diffusion of ions. |
| exocytosis | mechanism by which substances are moved from the cell interior to the extracellular space as a secretory vesicle fuses with the plasma membrane. |
| endocytosis | means by which fairly large extracellular molecules or particles enter cells e.g. phagocytosis, pinocytosis, receptor mediated |
| vesicular transport | fluids containing large particles and macromolecules are transported across cellular membranes inside bubble -like, membranous sacs. |
| transcytosis | moving substances into, across, and then out of cell. |
| vesicular trafficking | moving substances from one area (or membrane organelle) in the cell to another. |
| endosome | sorting vesicle that meets the now uncoated vesicle of the substance during endocytosis |
| phagocytosis | engulfing of foreign solids by its kind of cells |
| amoeboid motion | The flowing movement of the cytoplasm of a phagocyte |
| pinocytosis | engulfing of extracellular fluid by cells. |
| receptor mediated endocytosis | the type of endocytosis in which engulfed particles attach to receptors before endocytosis occurs. |
| caveolae | |
| membrane potential | voltage across the plasma membrane. |
| resting membrane potential | the voltage that exists across the plasma membrane during the resting state of a n excitable cell'ranges from-90 to -20 millivolts depending on cell |
| polarized | State of plasma membrane of an unstimulated neuron or muscle cell in which the inside of the cell is relatively negative in comparison to the outside'the resting state. |
| cell adhesion molecules | |
| membrane receptors | A large diverse group of integral proteins and glycoproteins that serve as binding sites for signaling molecules |
| ligands | chemicals that bind specifically to plasma membrane receptors. |
| G protein linked receptors | |
| G protein | protein that relays signals between extracellular first messengers(such as hormones or neurotransmitters) and intracellular second messengers(such as cyclic AMP) via an effector enzyme. |
| second messengers | intracellular molecule generated by the binding of a chem (hormone or neurotransmitter) to a receptor protein; mediates intracellular responses to the chem messenger |
| cyclic AMP | intracellular second messenger that mediates the effects of the first(extracellular) messenger (hormone or neurotransmitter);formed from ATP by a plasma membrane enzyme(adenylate cyclase). |
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