Biochemistry 2280A Chapter 12: Topic 6 - Textbook Notes - Chapter 12
19 Jul 2016
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Biochemistry 2280 topic 6 lipids and membranes. Lipid bilayers are impermeable to ions and most uncharged polar. Rate of diffusion through plasma membrane, from highest to lowest: small nonpolar molecules. Ex. oxygen, carbon dioxide: uncharged polar molecules. Ex. water, ethanol: larger uncharged polar molecules. Charged molecules are not allowed to enter: ex. Ion concentrations inside cell are very different from outside. Most important inorganic ions na+, k+, ca2+, cl-, h+ Na+ and cl- are most abundant outside cell. K+ is most abundant inside cell: balanced by negatively charged nucleic acids, proteins, and metabolites. Differences in concentration of inorganic ions across cell membrane. Resting membrane potential: voltage difference across membrane of unstimulated cell: in animal cells, this can be between -20 and -200 millivolts, it is negative because interior is move negative than exterior. Membrane potential used to communicate with surrounding cells. Membrane potential maintained by membrane transport proteins. Cells contain two classes of membrane transport proteins:
