BIOL107 Lecture Notes - Lecture 4: Lipid Bilayer, Facilitated Diffusion, Aquaporin

• School: University of Alberta
• Department: Biology (Biological Sciences)
• Course: BIOL107
• Professor: Carla Salvado

Document Summary

Due to their hydrophilic nature, these low molecular weight nutrients cannot diffuse across the plasma membrane, but rather are imported by cells through nutrient transporters of the solute carrier family. Cellular wastes are excreted by exocytosis when the vacuoles merge with the cell membrane and excrete wastes into the environment: membrane structure results in selective permeability. The plasma membrane is the boundary that separates a living cell from its surroundings. Exhibits selective permeability, allowing some substances to cross it more easily than others. The plasma membrane controls the exchange of materials of a cell with its surroundings: the permeability of the lipid bilayer. Hydrophobic (non-polar) molecules can dissolve in the lipid bilayer and pass through the membrane rapidly. Polar molecules do not cross the membrane easily: transport proteins. Transport proteins allow hydrophilic substances to pass across membrane. Have hydrophilic channel that certain molecules or ions can use as a tunnel (ex: aquaporins facilitate passage of water).