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Homeostasis

Homeostasis. All cells must maintain an internal balance For animal cells : Allow glucose, oxygen and water in Export wastes and carbon dioxide out. Selectively Permeable. The ability of a membrane to allow some substances to pass through while keeping others out Strainer Filter

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Homeostasis

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  1. Homeostasis • All cells must maintain an internal balance For animal cells: • Allow glucose, oxygen and water in • Export wastes and carbon dioxide out

  2. Selectively Permeable • The ability of a membrane to allow some substances to pass through while keeping others out • Strainer • Filter • Screen door • ???

  3. Structure of the Plasma Membrane • Phospholipid Phosphate Lipids http://telstar.ote.cmu.edu/biology/downloads/membranes/

  4. Phospholipid Bilayer Meaning that there is two layers of the phospholipid molecule http://www.wiley.com/college/pratt/0471393878/student/animations/membrane_transport/index.html

  5. Protein Molecules • Are embedded throughout the bilayer, serve as channels for materials to pass through the membrane • http://home.earthlink.net/~shalpine/anim/Life/memb.htm • http://www.wisc-online.com/objects/index_tj.asp?objid=AP1101

  6. Fluid Mosaic Model • The phospholipids are not bonded to each other and can freely move sideways throughout the bilayer • http://www.stolaf.edu/people/giannini/flashanimat/lipids/membrane%20fluidity.swf • http://telstar.ote.cmu.edu/Hughes/tutorial/cellmembranes/bil.swf

  7. Diffusion • The movement of particles from areas of high concentration to areas of low concentration • http://www.stolaf.edu/people/giannini/flashanimat/transport/diffusion.swf • http://www.wisc-online.com/objects/index_tj.asp?objid=AP1903 • Movement occurs until dynamic equilibrium is reached – continuous movement with no overall change • Smells, dyes, ??

  8. Osmosis • The diffusion of water molecules through a membrane from a high to low concentration • http://www.tvdsb.on.ca/westmin/science/sbi3a1/Cells/Osmosis.htm

  9. Active Transport • Movement of materials against the concentration gradient • Requires energy!!! • http://programs.northlandcollege.edu/biology/Biology1111/animations/transport1.html • http://www.stolaf.edu/people/giannini/flashanimat/cellstructures/phagocitosis.swf • http://www.wisc-online.com/objects/index_tj.asp?objid=AP11203

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