BISC207 Lecture Notes - Lecture 9: Cholesterol, Osmosis, Membrane Structure

• School: University of Delaware
• Department: Biological Sciences
• Course: BISC207
• Professor: Nauen Jennifer

Document Summary

Chapter 2 part 2: membrane structure and function. Bilayer, consists of two layers of phospholipids. Most common membrane lipid is a phospholipid. Polar heads orient themselves towards water, the hydrophobic tails interact with each other. Phospholipids in the different bilayers may differ in saturation (top or bottom, internal or external) Head groups may differ in size, shape, or charge. Layers can differ in composition from each other. Membranes are fluid; within a leaflet, the components move. Membranes are permeable; molecules can move through membranes. Ions do not move across membrane due to charged heads. Lipid bilayer w short unsaturated hydrocarbon tails = higher permeability and fluidity. Lipid bilayer w long and saturated hydrocarbon tails = lower permeability and fluidity. Not a bad thing, cells like to keep a certain permeability. Temp has a big effect on fluidity. Cells that don"t regulate internal temp, will remodel membrane if environmental temp shifts. Cholesterol stabilizes fluidity and decreases permeability of animal membranes.