phosphatidyl serine, phosphatidyl inositol, and diphosphatidyl glycerol are shown in Fig 1-4. The
second major class of membrane lipids are that of glycolipids; these are based on the molecule
sphingosine (see Fig 1.5c). Though they possess the basic tuning-fork design of the
phosphoglyceride they differ from them in several ways. The first long chain component is
always a 15:1 hydrocarbon, which moreover, is linked to the base by a simple carbon-carbon
bond rather than the ester bond (-COO-) found in the phosphoglycerides. In addition, a hydroxyl
group is retained. Sphingomyelin, a phospholipid that lacks a glycerol backbone, is found mainly
in plasma membranes (see Fig 1.5b). Instead of a glycerol backbone, it contains sphingosine, an
amino alcohol with a long unsaturated hydrocarbon chain. In sphingomyelin, the hydrophilic
head is similar to that of phosphatidylcholine. In Figure 1.5 the hydrophobic portions of all
phosphatidyl serine, phosphatidyl inositol, and diphosphatidyl glycerol are shown in Fig 1-4. The second major class of membrane lipids are that of glycolipids; these are based on the molecule sphingosine (see Fig 1.5c). Though they possess the basic tuning-fork design of the phosphoglyceride they differ from them in several ways. The first long chain component is always a 15:1 hydrocarbon, which moreover, is linked to the base by a simple carbon-carbon bond rather than the ester bond (-COO-) found in the phosphoglycerides. In addition, a hydroxyl group is retained. Sphingomyelin, a phospholipid that lacks a glycerol backbone, is found mainly in plasma membranes (see Fig 1.5b). Instead of a glycerol backbone, it contains sphingosine, an amino alcohol with a long unsaturated hydrocarbon chain. In sphingomyelin, the hydrophilic head is similar to that of phosphatidylcholine. In Figure 1.5 the hydrophobic portions of all
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