BIO 1140 Lecture 5: Lecture 5-6 Cell Membranes.doc
7 Mar 2012
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Document Summary
Fluid mosaic model: singer and nicolson 1972. Fluid lipid molecules in which proteins are embedded and freely floating. The membrane is held together by non-covalent interactions. Functions: because the membrane is made up of lipids, only molecules that are soluble in lipids can cross the barrier. This is called selectively permeable : membranes provide a structure for organizing proteins, regulation of solute transport: in and out of the cell and the organelles. E. g. the sodium pump: responses to external signals: is the first point of contact to the external environment. Receptors and signal transduction occur on the membrane: cell-to-cell communication: recognition, adhesion and exchange of materials are due to the membrane via gap junctions, and plasmodesmata. Membranes: mitochondrial membranes have many proteins within them, more than average has about 74% protein and 26% lipid, plasma membrane of schwann cell (myelin sheath) has about 18% protein and 82% lipid.
