BSC-2010 Lecture Notes - Lecture 5: Lipid Bilayer, Vegetable Oil, Cell Membrane
20 Oct 2016
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Document Summary
Plasma membrane is the boundary that separates the living cell from its surroundings. Phosolipids are the most abundant lipid in the plasma membrane. Amphipathic molecule that has hydrophobic and hydrophilic regions. Phospholipids in the plasma membrane can move within the bilayer. Rarely, a lipid may flip-flop transversely across the membrane. As temps cool, membranes switch from fluid state to a solid state. Membranes rich in unsaturated fatty acids are more fluid than those rich in saturated fatty acids. Membranes must be fluid to work properly; they are usually about as fluid as salad oil. At warm temp, 37 c, cholesterol restrains movement of phospholipids. A membrane is a collage of different proteins, often grouped together, embedded in the fluid matrix of the lipid bilayer. Six major functions of membrane proteins: transport, enzymatic activity, signal transduction, cell-cell recognition, intercellular joining, attachment to the cytoskeleton and extracellular matrix (ecm) Transport proteins allow passage of hydrophilic substances across the membrane.
