BIOL 122 Ch 7 Membrane Q's!

What is the fluid mosaic model? What does it refer to?
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How would you classify (active/passive transport) diffusion? What causes diffusion (simple diffusion)?Passive transport Simple diffusion is caused by random motion of moleculesHow is diffusion (simple diffusion) different from facilitated diffusion?Facilitated diffusion is when larger polar molecules need help transporting across the membrane (transport protein helps)What is the concentration gradient of a molecule? Would a molecule diffuse up (from low to high conc.) or down (from high to low conc) its concentration gradient?A concentration gradient is the difference in concentration of a substance from one location to another. A substance will diffuse from where it is more concentrated where it is less concentrated, down the concentration gradientAs molecules diffuse across a semipermeable membrane they will reach a dynamic equilibrium. What does this mean? How is it different from a static equilibrium?Dynamic equilibrium means as many molecules pass one way as the other direction. Static equilibrium means there is no movement between the reactants/productsWhat is osmosis?Osmosis is the net movement of water molecules over a slightly permeable membrane down its concentration gradient2 solutions are separated by a semipermeable barrier that allows the flow of water molecules, but not the solutes. Solution A is hypertonic to solution B. A | B. How would you classify solution B. Which way will water molecules flow? (from A B or from B A)?Solution B is hypotonic, the water molecules will flow from B to A (more water --> to less water) water wants to be hypertonic.A blood cell is placed into distilled water. How would you classify the distilled water (hypo, hyper, isotonic compared to the cell)? How would you classify the solution in the cell in comparison to the distilled water? Which direction would the water molecules flow (into the cell / out of the cell)?The DI water is hypotonic (has more water) The soln in the cell is hypertonic (has less water) The water molecules will flow into the cellA piece of celery is placed into salt water. Would you expect the cells to celery to become more flaccid or more turgid? Why?Flaccid- the water from the celery will go out of those cells into the salt water because salt water is hypertonic compared to the celeryWhat is osmoregulation? What organisms need to do this?Osmoregulation is the regulation of osmosis to maintain the internal environment (maintains homeostasis). Many vertebrates, including humans, are osmoregulatory.What is an electrochemical gradient? Which side of the plasma membrane is electronegative? What forms this gradient?An electrochemical gradient is created actively so the passive transport of cations into the cell and anions out of the cell will be favored by passive diffusion. The inside is more electronegative. Electrogenic pumps form the gradient (active transport)How does the Sodium-Potassium pump work? Is this active or passive transport? Why?The sodium-potassium pump system moves sodium and potassium ions against large concentration gradients. It moves two potassium ions into the cell where potassium levels are high, and pumps three sodium ions out of the cell and into the extracellular fluid. It is active transport (uses ATP)How does cotransport work?A transport protein couples the diffusion of a solute down its concentration gradient with the "uphill" transport of a different solute against its gradient.The transfer of materials out of a cell using vesicles is called _______ExocytosisHow do the three major types of endocytosis differ from one another?1. phagocytosis- "cell eating" 2. receptor mediated- grabbing specific things 3. pinocytosis- "cell drinking"