2019年最新-FacilitatedDiffusionandActiveTransport：易化擴散和主動運輸-精選文檔

1、Facilitateci Iliffusion and Active Transport Facilitated Diffusion Movement of specific molecules across cell membranes through protein cha nnelsI Each protein channel only allows a particular substances to crossThe protein facilitates (helps) the diffusion across the membraneOccurs with the followi

2、ng:1. Charged molecules (ions) 2. When molecules are too largeAlthough facilitated diffusion is fast andspecific, it is still diffusion.H Net movement of molecules across a membrane occurs from the side with a higher concentration lower concentration side.Does not require energy.Aftive Transoort Act

3、ive Tran sport en ergy-requiri ng process that moves material across a cellmembrane against a concentrationdifference "i9= energy used in active transportActive Transport Move materials in the opposite di rectionagai nst a concentration difference Requires:1 energy+ + + + + + + + + HIGH +2. tra

4、nsport proteinsExamples <f Active Transport1. Endocytosis2. Exocytosis3. Molecular Tran sport (use of protei ns or protein channels) EndocHosis Process by which a cell takes materialinto the cell byinfoldings or pocketsof the cell membrane.HBTransports:Larger molecules2. Solid clumps of materiale

5、n ergyPhagocytosis - “cell Phagocytosis 一 when extensions of the cytoplasm surround particles, package it within a food vacuole, then cell engulfs iti The process of engulfing takes a LOT ofScanning electron micrograph of a phagocyte (yellow, right) phagocytosing anthrax bacilli (orange, left)Pinocy

6、tosls ucell drinking Just like endocytosis; process where cells take up liquid from the surro un dingVesicleenvironment, fuse with membrane，and release these fluid filled vacuoles within the cell.ExocytosisExocytosisl- Process by which a cell releases large amounts of material. Vacuole fuses with cell membra neTran sports:Larger molecules2. Solid clumps ofmaterialMolecular Transport Na/K Pump (Sodium/Potassium Pump) Cells contain high amounts of K inside the cell and high amounts of Na outside the cell and，in order to maintain cell volume and resting cell potential, this pump gets used.hig