Physiology 1021 Lecture Notes - Lipid Bilayer, Electrochemical Gradient, Ion Channel

• School: Western University
• Department: Physiology
• Course: Physiology 1021
• Professor: Tom Stavraky

Document Summary

Proteins, nucleotides, (large molecules, needed for inside cell) cannot penetrate. Other molecules, many ions can, selectively permeable. Helps make membrane impermeable to some h2o. Can act as gates or channels (control subst in/out of cell) Can anchor some cell organs to inside of cell memb. Hydrophobic tails are major barrier to water-soluble substances. Fat-soluble subst. like o2, co2, steroid hormones can penetrate (can dissolve in lipid region of memb) Functions: receptor: attachment of chem hormones and neurotransmitors, enzyme: catalyst in chem rxns/breakdown molecules, membrane-transport carriers: transport molec. across membrane (may include gated channels, cell-identity markers: glycoproteins/antigens: foreign particles, can stimulate immune system. Ion channel/pore: all water-soluble subst (ions) into cell. **most important fn of proteins: transport substances across membrane: endocytosis/exocytosis (pinocytosis for small molecules, diffusion through the lipid bilayer (fat-soluble molecules, diffusion through protein channels(water-soluble molecules, facilitated diffusion, active transport. Movement of molecules of high concentration to low, due to random thermal motion.