ABSTRACT
The membranes of cells and viruses are the fundamental architecture upon which both function and structure of these biological entities are built. All cells and some viruses are bounded by a membrane, providing the de˜nition of the outer extremities of the cell or virus. Membranes provide fundamental compartmentalization, creating a distinction between the inside and outside of a cell or a virus. Compartmentalization provides an opportunity for differentiation of the inside from the outside of the cell, creating a key opportunity for development in the evolution of the most primitive forms of life. In addition to the bounding function, the exterior membrane must provide communication between inside and outside and the ability to move molecules (“food and wastes”) selectively from the inside to the outside and from the outside to the inside of the cell. In eukaryotic cells, membranes provide complexity in structure and differentiated function through intracellular organelles that are each constructed of unique membranes, differing in composition and function from the plasma membrane and from each other. In many cases, the membrane architecture provides biological functions uniquely derived from that structure in addition to compartmentalization of intracellular function.
