MCD BIO 165A Lecture Notes - Lecture 3: Lipid Raft, Membrane Fluidity, Membrane Lipids
23 Oct 2018
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Membrane fluidity: membrane lipids exist in gel or liquid-crystal phases depending on temperature, lipid composition and saturation in the presence of cholesterol. Unsaturated fatty acids lower the temperature at which the liquid-crystal/gel phase. Liquid-crystal membranes predominate transition occurs (transition temperature: temperature required for membrane to go from gel state to a more fluid state) Allows proteins to move in the membrane and for membranes to assemble and compromise between structural rigidity and complete fluidity grow: maintaining membrane fluidity. Organisms (other than birds and mammals) (cid:272)a(cid:374)"t (cid:373)ai(cid:374)tai(cid:374) ho(cid:373)eostasis -> maintain membrane fluidity as temperature changes by altering the composition of membrane lipids. Remodeling lipid bilayers involves saturation or desaturation of acyl chains and replacement of acyl chains by phospholipases or acyltransferases. The importance of these mechanisms has been verified using mutants unable to carry out certain desaturation reactions in response to cold: lipid rafts.
