BIOL 112 Chapter Notes - Chapter 5: Membrane Fluidity, Lipid Bilayer, Lipid Raft

• School: UBC
• Department: Biology
• Course: BIOL 112
• Professor: Karen Smith

Document Summary

5. 1 cell membranes are composed of lipids, proteins, and carbohydrates: phospholipids have hydrophilic heads and hydrophobic tails(amphipathic), and form micelles and bilayers when placed in aqueous environment with cellular ph, micelles: spherical structures. Hydrophobic: temp affects fluidity, cholesterol decreases fluidity at cellular temp because rigid ring structure interaction with phospholipid fatty acid tails reduces mobility of phospholipids. Low temps inc fluidity because chol stands in between phospholipids, preventing them to pack tightly together: me(cid:373)(cid:271)(cid:396)a(cid:374)e does(cid:374)"t s(cid:449)it(cid:272)h f(cid:396)o(cid:373) fluid to solid state. Lipid rafts: contain high concentrations of cholesterol and sphingolipids. Interact with either polar lipid heads or integral mem prot by weak noncovalent bonds: transmits info received from external signals, limit ability of transmembrane proteins to move, assist proteins in clustering in lipid rafts, fluid mosaic model. 5. 3 prokaryotes and eukaryotes differ in their degree of compartmentalization: prokaryotic cells, lack nucleus and other internal membrane-enclosed compartments.