12. Biophysics of cell membranes, membrane models.

main functions of the cell membrane

Diffusion barrier, electrical barrier
Transport: controlled material flow
Signal transmission: detection and transmission of electrical and chemical signals

Lipid components of the membranes

phospholipids, cholesterol, other lipid molecules

amphiphilic molecules

the larger part of the molecule is hydrophobic, the smaller part is hydrophilic

Singer and Nicolson-Fluid-mosaic model

The name mosaic refers to the fact that the membrane consists of many different components: proteins, carbohydrates and lipids, which cover the surface of the cell like the tiles of a mosaic.
The model developed in 1972.

Frye and Edidin

biological membranes are dynamic

Microdomains-lipid drafts

lipid rafts contain higher amounts of glycosphingolipids and cholesterol.
Task: compartmentalization, signaling process platform

membrane penetration mechanism

1. diffusion through a water channel
2. diffusion through the lipid phase
3. with the help of transporters in the membrane