We were anticipating that specific phospholipids may diffuse more quickly or slowly based on the structure of the individual acyl tails. However, we instead see that the diffusion coefficients between phospholipids are highly similar, with the diffusion coefficients for cis phospholipids ranging between 6-7×10 -8 cm 2 /s, and trans phospholipids demonstrating diffusion coefficients between 5-5.5×10 -8 cm 2 /s (Fig. ). The exception is the much more massive cardiolipin that diffuses considerably more slowly than the other lipids. The impact of isomerization on diffusion, approximately a 10-20 % decrease for trans membranes, is much smaller than other modifications bacteria make to their membranes, such as glycosylation in lipopolysaccharides, which may slow down lipid lateral diffusion by 100-fold. Lipids Tail Surface Accessibility