The effects of temperature and lipid composition on membrane fluidity are often

Question

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 1: Made entirely from phosphatidylcholine with saturated 16-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. After determining the transition temperatures of samples representing each of the membranes, you discover that your lab partner failed to record which membranes the samples correspond to. The three values you determined are -36C, 23C, and 41C. Assign each of these transition temperatures to the correct artificial membrane, and explain your reasoning. Drag the terms on the left to the appropriate blanks on the right to complete the sentences. Not all terms will be used.

Explanation / Answer

Membrane 1 has uniformly long and saturated fattyacids, so it has highest transition temperature.(41 degree c)

Double bonds disrupt phospholipid packing in the membrane, so membrane 2 has the lowest transition temperature (-36 degree c)

The shorter fatty acid tails of membrane 3 willlowerthe transition temperature noticeably but notdrastically, so this membrane will havethe intermediatetransition temperature (23 degree c).

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