11:115:301 Lecture Notes - Lecture 8: Lipid Bilayer, Stereochemistry, Archaea
22 Sep 2019
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Document Summary
Archaea have lipids without fatty acids or esters. Archaea differ from eukaryotes in three ways: Nonpolar chains are joined to glycerol backbone by ether linkages. Ether linkage more resistant to hydrolysis. Branched, saturated hydrocarbons are more resistant to oxidation than the unbranched chains of eukaryotic and bacterial membrane lipids. Cholesterol is a lipid based on a steroid nucleus. Makes the membrane a sense organ for the cell. Contain carbohydrates that are linked to lipids + proteins. Forms closed bimolecular sheets in aqueous media. Lipids bilayer barriers to the flow of polar molecules. Serve as pumps, channels, receptors, energy transducers, enzymes. Protein + lipids are held together by noncovalent interactions. Two faces of membranes differ from each other. Lipids + proteins diffuse rapidly in the place of membrane. Lipids + proteins do not rotate across the membrane. Membrane potential transport, energy transport, excitability. Not generally able to flip-flop or leave membrane. Degree of fluidity of the lipid phase is determined by:
