Most of these units are limited by one or more membranes. To perform the function of the organelle, the membrane is specialized in that it contains specific proteins and lipid components that enable it to perform its unique roles for that cell or organelle. In essence membranes are essential for the integrity and function of the cell. This allows the cell to maintain its shape and perhaps move to distant sites. How would you distinguish tight, or occluding junction between two cells, both structurally and functionally.
Architecture allows for fluidity and order.
Each molecular component has unique functions vital to the cell and its domain Membranes help organize the cell into domains and microdomains .