MCB 2007 October 22nd Lecture Notes

MCB 2007 October 22nd Lecture Notes - partition into a...

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October 22 nd Lecture Notes: (Start of Exam #3 material) Membrane Transport (Ch. 12) ~ Principles of Membrane Transport o The ion concentrations inside a cell are very different from those outside the osmotic and ionic balances must be maintained by a cell Na + is high inside the cell, K + is high outside the cell…very important in signaling (action potentials) o Lipid Bilayers are impermeable to solutes and ions simple diffusion rates of a solute depend on their size and solubility small, nonpolar molecules diffuse easily across next easiest = small hydrophobic solutes large polar and ions (small and charged) will not diffuse at all was measured using synthetic lipid bilayers…rates of diffusion were measured permeability coefficients (P) are proportional to the likelihood of diffusion for a molecule (its tendency to
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Unformatted text preview: partition into a lipid bilayer) transport proteins facilitate the regulation of the osmotic balance within a cell, since ions cannot diffuse readily across the lipid bilayer of a membrane cells must maintain osmotic balance and electrical neutrality despite large differences in solute concentrations across cell membranes ions and hydrophobic molecules have low permeabilities need to be transported across somehow o Membrane transport proteins fall into two classes: carriers and channels very large and diverse protein familylarge number of transporters lots of molecules need to be transported (sugars, amino acids, nucleotides, ions, atp, protons) differ from membrane to membrane according to membrane function...
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MCB 2007 October 22nd Lecture Notes - partition into a...

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