The Nature of Cells A. Basic Cell Features 1.
All cells have a plasma membrane, cytoplasm, and a nucleus.
A plasma membrane separates each cell from its environment, permits the flow of molecules across the membrane, and contains receptors that can affect the cell's activities. Also, it would be difficult to move things like food, wastes, and proteins being assembled around in a larger volume of cytoplasm. C. Microscopy 1. Where the telescope ends, the microscope begins. Cell Membranes A. Membrane Structure and Function 1.