BIO 201 Lecture Notes - Lecture 12: Cell Membrane, Membrane Fluidity, Lipid Raft

• School: University at Buffalo
• Department: Biological Sciences
• Course: BIO 201
• Professor: Lara Hutson

Document Summary

Lecture 12: structure of the plasma membrane (ch. Intercellular junctions: direct connections between cells (with or without signaling) Membranes ~70-80 angstroms thick = ~2x length of a typical phospholipid. Have a (cid:862)(cid:396)ail(cid:396)oad t(cid:396)a(cid:272)k(cid:863) appea(cid:396)a(cid:374)(cid:272)e i(cid:374) t(cid:396)a(cid:374)s(cid:373)issio(cid:374) ele(cid:272)t(cid:396)o(cid:374) (cid:373)i(cid:272)(cid:396)os(cid:272)opy (cid:894)tem(cid:895) Measuring membrane fluidity: fluorescence recovery after photobleaching (frap) Less fluid (better at high temp ) more fluid (better at low temp) High temperature: cholesterol high tm dominates. (preventing the melting of the membrane, so that it increase the membrane temperature) result: increases tm at high temperature. Low temperature: cholesterol inhibits phospholipid tail interactions: result: lowers tm at low temperature. Approximate content of biological membranes (numbers: % of total mass of the membrane) Incomplete recovery during frap sub part of the membrane failed to recover. Protein with related function colocalize in lipid rafts improved efficiency! Cholesterol itself have high tm and low fluidity. Observation: red blood cells (rbcs) shrink when placed in high salt concentration.