Paul Andersen explains how cells are selectively permeable with the help of their cell membrane. The main constituents of the cell membrane, including cholesterol, glycolipids, glycoproteins, phospholipids, and proteins are included. The fluid mosaic model is also illustrated. The cell wall in plants, bacteria, and fungi is also discussed.

Paul Andersen describes how cells move materials across the cell membrane. All movement can be classified as passive or active. Passive transport, like diffusion, requires no energy as particles move along their gradient. Active transport requires additional energy as particles move against their gradient. Specific examples, like GLUT and the Na/K pump are included.

In this video Paul Andersen defines water potential and explains how it can be calculated in a simple system. He explains how water can moved through osmosis and break down the two major parts of water potential (solute potential and pressure potential). He finishes the video with a sample calculation of solute potential.