City University of New York
The World of Cells: Plasma Membrane
This is a basic description of the structure of cell membranes. Site provides colorful pictures of each membrane.
PBS
Pbs Learning Media: Cell Membrane: Just Passing Through
This interactive feature describes some of the most important structures and functions of the cell membrane.
Other
Biology Guide: Molecules, Cells, and Systems
Students learn about molecules, cells, and systems. Some topics investigated in the tutorial are cell types, enzymes, plasma membranes, and the heart.