Topic: Chapter 7, Membrane Structure 1. The effects of temperature and lipid com
ID: 191485 • Letter: T
Question
Topic: Chapter 7, Membrane Structure 1. The effects of temperature and lipid composition on membrane fluidity are often studied by using artificial membranes containing only one or a few kinds of lipids and no proteins. Assume that you and your lab partner have made the following artificial membranes: Membrane : Made entirely from phospholopids with saturated 20-carbon fatty acids. Membrane 2: Same as membrane 1 except that each of the 16-carbon fatty acids has a single cis double bond. Membrane 3: Same as membrane 1 except that each of the saturated fatty acids has only 14 carbon atoms. e except that each of the 16-carbon fatty acids has a single trans double bond. Rank these membranes based on their transition temperatures (starting from highest to lowest). Explain your reasoning.Explanation / Answer
Membrane 2(single cis double bond)>mambrane2(single trans double bond) > Membrane 3> Membrane 1
longer fatty acids are more rigid, reduce membrane fluidity and permeability
unsaturated fatty acids increase membrane fluidity and permeability by disrupting close packing of fatty acid tails by putting kinks when comparing with a membrane made of saturated fatty acid. saturated fatty acid causes lipids tail to be packed closely, therefore, provide more rigidity and less fluid, however fluidity increases in the membrane with shortening of chain length in saturated fatty acid as the shorter chain has less surface area to undergo van der Waals interaction with neighboring fatty acid chain.
Cis-unsaturated fatty acids are even more bent and disruptive than trans unsaturated fatty acid provide more fluidity to lipid membrane than membrane containing trans-unsaturated fatty acid. This bending is conferred by the position of hydrogen around a double bond. In cis two hydrogens are on the same side of double bond whereas in trans they are on opposite side which causes nearly straight chain formation
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