Molecules that consist of both a hydrophobic and a hydrophilic part are called amphiphiles (amphi = both). Amphiphile molecules orientate their domain with the highest affinity for the solvent toward that solvent, while the other part of the molecule turns to avoid contact with the solvent. In this way amphiphilic molecules align according to well-defined patterns and give rise to pluriform aggregates. The shape of the aggregates is determined by the ratio between the size of the hydrophilic and the hydrophobic part as well as the nature of the solvent. The washing property of soap is based on amphiphiles that interfere between water and (fatty) dirt. Amphiphiles also form the main part of the cell membranes that serves to delimit and protect cellular compartments