Physiology 1021 Lecture Notes - Lecture 4: Lipid Bilayer, Facilitated Diffusion, Membrane Transport

• School: Western University
• Department: Physiology
• Course: Physiology 1021
• Professor: John Ciriello

Document Summary

Interactions of cell with environment sept 9 2014-09-11 1:52:00 am. Role of cell membrane in cellular communication and homeostasis. Messages begin to be processed at cell membrane of must pass through cell membrane in order to be processed. Four functions of membrane proteins: ion channels, enzymes, receptors, membrane carriers. Some molecules are unable to cross the cell membrane due to size or composition. Mechanisms of membrane transport: endocytosis and exocytosis, diffusion through lipid bilayer (fat-soluble molecules, diffusion through protein channels (water-soluble molecules, facilitated diffusion, active transport. Diffusion with protein channels: ions cannot cross the cell membrane by simple diffusion therefore they are granted access by a channel protein and follow the pathway from high concentration to low concentration. The movement of ions depend on the electrical and chemical gradient (electrochemical). Facilitated diffusion lock in key method: specific molecule binds to molecule specific protein, changes shape and allows the release of the molecule into the area of low concentration, no energy.