320Fall09Lecture6 - BIO 320 Cell Biology, Fall `09 Dr....

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BIO 320 Cell Biology, Fall ‘09 Dr. Thomas Bushart Lecture 6
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Topics Lipids and membranes Membrane-protein interaction
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Baseline permeability Lipid-only membranes have natural permeability I Mostly predictable based on bilayer properties Limits on ion movement I Polar-nonpolar interaction I Stripping of hydration shell Proteins are major component modifying this permeability Figure 11-1 Molecular Biology of the Cell (© Garland Science 2008)
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Why so much transport? A great deal of cellular energy is involved in moving around small ions and molecules Table 11-1 Molecular Biology of the Cell (© Garland Science 2008)
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Purposes of ion transport Rapid responses I Ca 2+ as a cellular signal Water balance I Osmolarity of cell Productive work I Synthesis of ATP
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Membrane transport proteins Transporters (carriers, permeases) I Bind solutes and carry out transport through conformational changes Channels I Aqueous pores through bilayer I Water channels/aquaporins aid in water permeability Figure 11-3 Molecular Biology of the Cell (© Garland Science 2008)
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Passive transport All channels and many transporters Solute allowed to flow down its concentration gradient but…. Figure 11-4a
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Charged molecules Both concentration gradient and electrical gradients impact diffusion of charged molecules I Electro chemical gradient Figure 11-4b Molecular Biology of the Cell
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Active transport Movement of molecules against their electrochemical gradient (+ G) I How to overcome the free energy problem?
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Coupling energy producing/capturing with solute movement Passive
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This note was uploaded on 09/15/2009 for the course BIO 320 taught by Professor Staff during the Fall '08 term at University of Texas at Austin.

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320Fall09Lecture6 - BIO 320 Cell Biology, Fall `09 Dr....

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