BIOL 112 Lecture Notes - Lecture 5: Lipid Bilayer, Synthetic Membrane, Sodium Silicate
27
BIOL 112 Full Course Notes
Verified Note
27 documents
Document Summary
Membranes are very fluid in order to allow proteins inserted into the membrane (integral membrane proteins or transmembrane proteins) to interact with each other. Usually membrane proteins are integrated into the membrane by means of one or multiple alpha-helices. The insertion of membrane proteins into the lipid bilayer introduces an asymmetry, because integral membrane proteins can only move laterally, not vertically. This means the side of the protein pointing outward never changes, the protein just moves around within the plane of the membrane (like phospholipids). Because freezing tightly binds phospholipids to surrounding water molecules by hydrogen bonds, whereas the two lipid leaflets are held together only by van der waals forces (in the frozen state). The main function of membranes is to serve as a barrier and to selectively transport molecules the cell needs or wants to get rid of. To analyze membranes, scientists prepare a beaker of water separated into two compartments.
