Fluid Mosaic Model of Membrane Structure

With the help of diagram, describe the the fluid mosaic model of membrane structure and it’s component (10 minutes, selanjar 1 06/07)

Answer scheme

Fluid mosaic model of cell membrane:

-The mosaic disposition of membrane protein in conjunction with the fluid nature of the

lipid bilayer described above, constitutes the basis of the fluid mosaic model for the

membrane structure.

-The protein is freely to move in the lipid like the floating iceberg in the sea.

-composed of: phospholipids, cholesterol, proteins and chains of oligosaccharides linked to phospholipids and protein molecules

Membrane Proteins:

1. Integral proteins: are directly incorporated into the lipid bilayer.

Some integral proteins span the membrane from one side to the other. They are called

transmembrane proteins.

2. Peripheral proteins: exhibit a loose association with the membrane surface

Membrane phospholipids:

-Examples: Lecithin, cephalin

- consist of two long, nonpolar (hydrophobic) hydrocarbon chains linked to a charged (hydrophilic) head group

- the phospholipids are organized into a double-layer with their hydrophobic chains directed towards the centre of membrane and their hydrophilic heads directed outwards.

- cholesterol breaks up the close packing of phospholipid long chains and this disruption makes the membrane more fluid.

- some lipids, called glycolipids, posses oligosaccharide chains that extend outward from the surface of the membrane

Glycocalyx (cell coat):

-With EM, the external surface of cell shows a carbohydrate-rich region called glycocalyx.

-is made of carbohydrate chains linked to membrane proteins and lipids and cell-secreted glycoproteins and proteoglycans

-Has a role in cell recognition and attachment to other cells and to extracellular molecules