Selective Permeability Fluid Mosaic Model Selective Permeability

Describes the arrangement of the molecules that make up the cell membrane. Membrane is flexible, not rigid. Phospholipids in each layer can move from side to side by sliding past each other . Membrane behaves like fluid. (Like oil on the surface of water)

Selective Permeability Allows some, but not all, molecules to cross through it. A cell needs to maintain certain conditions to carry out its functions. (Homeostasis) Must control the import or export of certain molecules. Molecules that can pass through the membrane freely: Small, uncharged molecules H20 (Water) O2 (Oxygen)