Cell structures and the gram stain

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.

What does gram positive mean

Updated October 15, Most bacteria are classified into two broad categories: Gram positive and Gram negative. Inside the cell wall or rigid peptidoglycan layer is the plasma cytoplasmic membrane; this is usually closely apposed to the wall layer. A peptidoglycan with a chemical structure substantially different from that of all eubacteria has been discovered in certain archaebacteria. At present, there is no satisfactory evidence to suggest that they have a unique biochemical or physiologic function. Note the complexity of the Gram-negative cell envelope outer membrane, its hydrophobic lipoprotein anchor; periplasmic space. Key Terms osmotic environment: environment with controlled net movement of molecules from a region of high solvent concentration to a region of low solvent concentration through a permeable membrane. Key Terms binary fission: The process whereby a cell divides asexually to produce two daughter cells. Download