Teichoic acids are linear polymers of polyglycerol or polyribitol substituted with phosphates and a few amino acids and sugars.
This phenomenon is observed in both gram-positive and gram-negative species. The dependence of bacterial shape on the peptidoglycan is shown by the transformation of rod-shaped bacteria to spherical protoplasts spheroplasts after enzymatic breakdown of the peptidoglycan.
Many bacteria possess plasmids which are the circular double stranded DNA molecules in addition to their chromosomes.
The number and distribution of flagella on the bacterial surface are characteristic for a given species and hence are useful in identifying and classifying bacteria. The organization and overall dimensions of the outer membrane of the Gram-negative cell envelope are similar to those of the plasma membrane about 7.
In the Gram-negative Bacteria the cell wall is relatively thin 10 nanometers and is composed of a single layer of peptidoglycan surrounded by an outer membrane. There are motile gram positive and gram negative bacteria.