ABSTRACT

The cell membrane is much more than a passive “bag” separating the cyto-plasm from the environment. It is a heterogeneous, regulated barrier that allows for both active and passive transport of substances between the inside and outside of the cell. Its mechanical integrity is fundamental to its barrier function. Bending and stretching of the membrane is centrally involved in exocytosis and vesicle budding, as well as in fusion and viral invasion. It also incorporates structures for interacting with the extracellular matrix, other cells, and various compounds in solution. Proteins trapped in the membrane allow for signaling between the inside and outside of the cell. Understanding the biology and mechanics of the membrane can foster an appreciation of the complexity of this fascinating cellular component. In this chapter, we discuss the cell membrane’s structural organization, how the two-dimensionality of the membrane limits diffusion, and how the barrier function can be understood. We end with a formal treatment of the cell membrane’s mechanical function.