All Biological Processes Involve Water

Life began in water, and every single function of life takes place in an aqueous environment. A profound way of classification in chemistry is the relation and interaction between molecules, or groups within molecules, and water. Molecules (or parts of molecules) can attract water in which case they are called hydrophilic. As the opposite extreme they can strive to avoid water; these molecules or molecular parts are termed hydrophobic. Most biomolecules possess both these properties; they are amphiphilic. This is a fundamental principle which determines the organisation of biomolecules- from the folding of peptide chains into native structures of proteins, to self-assembly of lipid and protein molecules into membranes. One consequence of the existence of these two media is that the interface between them define surfaces that tend to be closed. The lipid bilayer of membranes, for example, always form closed surfaces; the hydrocarbon chain core is never exposed to water. The curvature of these surfaces is an important concept in order to understand structural features above the molecular level. Surface and colloid science deals with forces involved in formation of such organisations. The behaviour of the colloidal state of matter involves van der Waals interaction, electrostatic forces, so-called hydration forces and hydrophobic forces.

[...]

Another important feature of the cell membranes is their control of topology in the cell - separation of the inside and the outside. Considering any cell in our body and moving backwards in time via the embryo and through earlier generations down the evolution, the DNA has never been exposed to the outside world. There is always a membrane enveloping DNA in all forms of life, as we know them. A closed membrane providing shape and topology is thus a necessity for life.

Which means that all molecules involved are of varying degrees hydrophilic and hydrophobic.