Lecture 21

Lectures: 1 | 2 | 3 | 4-5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 15 | 16 | 17 | 19 | 20 | 21 | 22 | 23 | 26

Membranes

1. Membrane Structure and Function Cells are Enclosed by Membranes:
   • Lipids (Amphiphylic Phosphoglycerids) are the Principal Component
   • Self-assemply into Micelles and Bilayers
2. The Canham-Helfrich Energy of a Membrane:
   • Differental Geometry: Principal, Mean, Gaussian Curvature of a Surface (Page 1 (GIF) of Lecture Notes)
   • Reparametrization Invariant Energy (Page 2 (GIF) of Lecture Notes)
   • Gauss-Bonnet Theorem
   • Vanishing Surface Tension; Why Bilayers form Vesicles? (Borders)
3. Red Blood Cells (GIF):
   • Predicting Shapes: Peterson, Syracuse U.
   • Membrane Fluctuations and 'Flicker' of Red Blood Cells
   • Persistence Length of Membranes (Page 3 (GIF) of Lecture Notes)
   • Flexibility of Cykoskeleton, and Aspirated Erythrocytes (PDF)
4. Transport in and out of Cells:
   • Why do Oxygen and Benzene Pass Through, but Smaller Ions do Not?
   • Passive Ion Channels and Active Ion Pumps
   • Intracellular and Extracellular Concentrations
   • The Nernst Equation and Membrane Potentials (Page 4 (GIF) of Lecture Notes)

Some Related Links

• Membrane Structure, from Cell Biology Topics (Gwen V. Childs, U. of Arkansas for Med. Sci.)
• Cell Membranes, from an On-Line Biology Book
• Sparks Notes on Cell Membranes
• Test Yourself with this Cell Membranes Tutorial from the University of Arizona Biology Project
• Kamien, Randall D. The Geometry of Soft Materials: A Primer. Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, Pennsylvania 19104 (September 11, 2002).
• Flexibility of Cell Membranes, from Physics Focus
• Transport Across Cell Membranes, from Kimball's Biology Pages