5.3 The Internal Organization of Cells

In addition to the plasma membrane, many cells contain membrane-bound regions within which specific functions are carried out. Such a cell can be compared to a large factory with many rooms and different departments. Each department has a specific function and internal organization that contribute to the overall “life” of the factory. In this section, we give an overview of two broad classes of cells that can be distinguished by the presence or absence of these membrane-enclosed compartments.