Peptidoglycan layer, Gram-negative bacteria

Gram-negative bacteria have a more complex cell surface. The peptidoglycan layer is also the outer layer with respect to the cytoplasmic membrane. However, besides this, they have another outer polysaccharide membrane. This outer membrane is built out of lipopolysac-charides and lipoproteins, and can be a serious barrier for permeating hydrophilic molecules. 

The cell wall from the Gram negative organism Escherichia coli is complex. As with many Gram negative bacteria, the cell wall of E. coli possess a periplasmic space, a gelatinous layer between the inner and outer membrane. It often contains some peptidoglycan molecules. 

Gram-negative bacteria Gram-positive bacteria Outer membrane No outer membrane peptidoglycan layer thicker peptidoglycan layer ... 

Gram-positive bacteria contain a rigid peptidoglycan cell wall surrounding the cytoplasmic membrane. Gram-negative bacteria contain an additional third, outer layer. This wall is a complex structure with lipoproteins and lipopolysaccharides. Synthesis of two outer walls from different bacterial cells is described in this concept screen ... 

---