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Unformatted text preview: ng relatively large head group attached to their single hydrophobic tail and therefore
cannot align side-by-side to form a bilayer. (b) In most glycerophospholipids, the20
width of the head group is comparable to the width of the two acyl chains. The lipids
can therefore form a bilayer with no voids between lipid molecules. (c) Triacylglycerols,
with a small and weakly polar head group, do not form a bilayer. bend and interdigitate. In addition, the head groups of membrane lipids are not of
uniform size, and their distance from the membrane center depends on how they
nestle in with neighboring head groups. Finally, the lipid bilayer is impossible to
describe in precise terms because it is not a static structure. Rather, it is a dynamic
assembly: The head groups bob up and down, and the hydrocarbon tails of the lipids
are in constant rapid motion. At its very center, the bilayer is as ﬂuid as a sample of
pure hydrocarbon (Fig. 8-5). This structure provides an answer to the question
posed at the start of the chapter: The bilayer is ﬂexible enou...
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This document was uploaded on 02/02/2014.
- Winter '14