A bacteria cell wall can vary in composition, certain cell walls may be more permeable than others, while at the same time you will find bacteria most often come in two shapes, rods or spheres. Additional shapes are not unusual although and include squares, spirals, stars triangles and bacteria that clump into nets, clusters or mounds. Technical classification of these shapes includes bacillus (bacilli as rods), coccus (cocci as spheres), vibrios (as bananas) and the helical (bacteria that resemble corkscrews.) Any of these bacteria can have varying dimensions in their thickness as well.
The cell wall is important because it can serve as a resistant barrier to some particles and other cells or it can be serve as a target. A cell wall lets a bacterial cell have its defining shape. The cell wall of a bacteria is sandwiched between the bacteria’s capsule and the plasma membrane. The capsule of the bacteria is structured from polysaccharide or proteins and helps in blocking the process of phagocytosis that relates to the white blood cells. While it is important to learn of the cell wall there are however cells without cell walls, these bacteria have no decided shape to them. and are referred to as mycoplasma.
If a bacteria is gram negative, the cell wall is thinner and there is another layer structured between the capsule and the plasma membrane, it is called the outer membrane, and it contains the toxic matter known as lipopolysaccharide. It is the lipopolysaccharide that turns on the immune system of the cell.
The cell wall of a bacterium is composed of peptidoglycan. The plasma membrane present in some of the bacteria that will be found lying over the cell wall of gram positive cells and over the periplasmic space of gram negative cells is a lipid layer. Within this lipid layer many protein cells move around transporting ions, nutrients or waste materials to their desired destinations.
Gram positive bacteria will have a thicker layer of peptidoglycan than gram negative bacteria, the bacteria will have a more smooth appearance overall while gram negative bacteria possesses a thinner layer of the peptidoglycan. The gram positive bacteria will have no lipids and in many instances, no proteins. Gram positive bacteria will also have the accessory polymers teichoic acid or teichuronic acid. The teichoic acids contain sugars with or without the amino acid known as amino acid D-alaniner. Sugars include Ribitol, Glycerol or Mannitol. Teichuronic acids contain amino acids and work interchangeably with teichoic acids. Gram negative bacteria look fuzzy under an electron microscope. When working with bacteria, one of the first things to determine is whether the bacteria are gram positive or gram negative in nature.