生物很多来自unit2the cell7

1、Chapter 7Membrane Structure & Function(Simple) Diffusiondown the concentration gradient: a substance will diffuse from where it is more concentrated to where it is less concentrated.dynamicdynamicOsmosisThe diffusion of free water across a selectively permeable membrane (either in living things or n

2、onliving things).Water Balance of Living CellsWater Potentialpsi () = p + s water potential = pressure potential + solute potentialPure Water = 0Water Potentialpsi () = p + s water potential = pressure potential + solute potentialWater Potentialpsi () 0 = p + s water potential = pressure potential +

3、 solute potentialhigh water potentiallow water potentialOsmosisWater will always flow from solution with high water potential (less solute) to low water potential (more solute).high water potentiallow water potentialPlasmolysis & DeplasmolysisFacilitated DiffusionChannel proteinsCarrier proteinsThe

4、protein can transport the solute in either direction, but the net movement is down the concentration gradient of the solute.aquaporinFLASH 7.2Active TransportMove solute against the gradient.Need transport proteins (carriers/pumps). Need energy (ATP) Active Transporte.g. electrogenic pump Ion pump (

5、Na-K pump)Proton pumpMembrane Potential: difference in electrical charge across plasma membrane due to differential distribution of ions.Electrochemical Gradient: diffusion gradient of an ion affected by concentration difference across membrane and tendency to move relative to the membrane potential

6、.Sodium-Potassium PumpTB-F7.18Sodium-Potassium PumpSodium-Potassium PumpFLASH 7.3CotransportCoupled transport by a membrane proteindownhilluphillFLASH 7.4How to cross the membrane?RG-C7-Q15Amoeba ingesting a ParameciumEndocytosis 胞吞Phagocytosis 吞噬作用Pinocytosis 胞饮Receptor-Mediated Endocytosis受体介导的胞吞E

7、xocytosis 胞吐FLASH 7.5Bulk TransportLarge molecules (proteins, polysaccharides)VesiclesNeed energy (ATP)Cross no membranes!Selective PermeabilitySelectively Permeable Membrane Semipermeable MembraneLab 4: Diffusion & OsmosisRead the lab manual.Answer the questions on the lab manual.Discuss & Design.C

8、onduct the experiment.Lab notes & Data.Write the lab report on the back of manual.2005(B)Q44. Water potential in potato cells was determined in the following manner. The initial masses of six groups of potato cores were measured. The potato cores were placed in sucrose solutions of various molaritie

9、s. The masses of the cores were measured again after 24 hours. Percent changes in mass were calculated. The results are shown below.2005(B)Q4(a) Graph these data on the axes provided. From your graph, find the apparent molar concentration (osmolarity) of the potato core cells.(b) What are the components of water potential, and why is water potential important for the movement