Lecture 2 - Bio 317 Lecture 2 Permeability of cell membrane...

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Bio 317 Lecture 2 Permeability of cell membrane Hydrophobic molecules pass through lipid bilayer READILY The more charged you are the less permeable Ions are almost impermeable Small and large polar molecules are more and less permeable respectively Embedded Proteins Carrier proteins Passive transport- requires no energy, concentration gradient is driving force Active transport- requires energy, ATP needed, can carry against Concentration gradient Diffusion does not need a carrier, hydrophilic molecules do not cross on their own they need channels or proteins, very fast! Linear relationship between velocity and concentration, no saturation! Ion channel- facilitated diffusion, down concentration gradient for ions Carrier-mediated- Protein interacts with molecule and then escorts it across membrane; once again the driving force is the concentration gradient…has a maximum speed at which this can be done. Can be active or passive. Saturation occurs, at low concentrations the transport is fast however at high concentration there is a lower velocity. Carrier protein-mediated active transport Coupled carrier- no ATP hydrolyzed directly…Sort of secondary active transport since it takes advantage of one substances (i.e. Sodium-inside to outside)) concentration gradient and transports the second molecule (i.e. glucose outside-inside) against C- gradient ATP driven pump- ATP hydrolyzed immediately every time usage is needed
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This note was uploaded on 05/18/2008 for the course BIO 317 taught by Professor Simonhalegoua during the Fall '08 term at SUNY Stony Brook.

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Lecture 2 - Bio 317 Lecture 2 Permeability of cell membrane...

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