Introductory Microbiology

Cell membrane

• Cell membrane is the bounding layer of the cytoplasmic contents and is the principal osmotic and permeability barrier. It is a lipoprotein devoid of any polysaccharide and when examined under an electron microscope appears as a 3 layer unit with a unit membrane structure.
• The polar head region of the phospho-lipids are located at the two outer surfaces while hydrophobic fatty acid chains extend to the centre of the membrane. The middle protein layer is intercalated into the phospholipids bilayer.
Functions:
1) It behaves as an osmotic barrier and contains permeases responsible for the transport of chemicals and nutrients in and outside the cell.
2) It contains the enzymes involved in the bio synthesis of membrane lipids and other various macromolecules of bacterial cell wall
3) It contains the components of the energy generation system. In addition to these, there is also evidence to show that the cell membrane has specific attachment sites for the replication and segregation of the bacterial DNA to the plasmids.