Figure 4.

Representative phases in a lipid bilayer: shown are three distinct phases namely the gel phase (a), the liquid-disordered, L_d phase (b), and the liquid-ordered, L_o phase (c). Solid and liquid implies that the nature of translational correlations in the plane of the membrane are either solid-like or liquid-like (top view of (a) shows a lattice structure, characteristic of a solid, while (b) and (c) have no lattice structure and hence are liquid like). Hydrophobic chains in the ordered phase and gel phase have strong orientational correlations, whereas those in the disordered phase have random orientations and thus have weak orientation correlations. In (c) the shaded triangles represent smaller lipid molecules like cholesterol and sphingolipids that intercalate into the hydrophobic region.