MCDB 310 Lecture Notes - Lecture 10: Membrane Transport, Semipermeable Membrane, Lipid Bilayer

• School: U of M
• Department: Molecular, Cellular and Developmental Biology
• Course: MCDB 310
• Professor: Kenneth Balazovich

Document Summary

Biological membranes: plasma membrane = outside of cell, organelles have membranes too. Molecular constituents of membranes: nearly all the mass of biological membranes is made up of proteins, polar lipid, and carbohydrate, each membrane has characteristic lipids and proteins, membrane lipids, each membrane type has characteristic lipids, vary. Implies there are regulatory controls on: lipid synthesis, lipid transport, membrane assembly, constituents vary with climate, but not with diet, diet determines what is available, not how it is used. Physical membrane properties are regulated by cells: lipid distribution, fluidity, curvature. Idea that membrane itself is very fluid, almost like a non-polar solvent: frap measurements, fluorescent recovery after photobleaching, watch area of membrane and watch the fluorescence returning, new lipids diffusing into this photobleached area. Membranes are patchy: cytoskeleton anchors membrane proteins, creati(cid:374)g (cid:862)fe(cid:374)(cid:272)es(cid:863) to separate protei(cid:374)s, cholesterol partitions lipids into micro-domains or rafts, different proteins prefer different lipid phases separation into different domains of membrane, critical temperature = transition temperature.