Lecture 5 Notes

Lecture 5 Notes - Lecture 5 Notes Chapter 11 Chapter 11...

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Chapter 11 - Given enough time, virtually any molecule will diffuse across a protein-free lipid bilayer down its concentration gradient. The rate of diffusion, however, varies enormously, depending partly on the size of the molecule but mostly on its relative solubility in oil. In general, the smaller the molecule and the more soluble it is in oil (the more hydrophobic, or nonpolar, it is), the more rapidly it will diffuse across a lipid bilayer. Small nonpolar molecules, such as O 2 and CO 2 , readily dissolve in lipid bilayers and therefore diffuse rapidly across them. Small uncharged polar molecules, such as water or urea, also diffuse across a bilayer, albeit much more slowly. By contrast, lipid bilayers are highly impermeable to charge dmolecules (ions), no matter how small: the charge and high degree of hydration of such molecules prevents them from entering the hydrocarbon phase of the bilayer. Thus, synthetic lipid bilayers are 10 9 times more permeable to water than to even such small ions as Na + or K + . o
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This note was uploaded on 11/22/2010 for the course BIOLGY BICD 110 taught by Professor Yiminzou during the Spring '10 term at UCSD.

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Lecture 5 Notes - Lecture 5 Notes Chapter 11 Chapter 11...

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