Lecture 21

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Membranes

Membrane Structure and Function Cells are Enclosed by Membranes:
- Lipids (Amphiphylic Phosphoglycerids) are the Principal Component
- Self-assemply into Micelles and Bilayers
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)
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)
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)

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