Types of Bacterial Cell Walls

Archaeal walls are different from bacteria because they do not contain peptidoglycan. Some contain pseudopeptidoglycan or have a cell wall made of glycoproteins or sugars. Some lack a cell wall entirely. 

Archaeal Cell Walls vs. Bacterial Cell Walls

Peptidoglycan makes up the cell walls of bacteria. It is composed of alterating long chain molecules called N-acetylglucosamine (NAG) and N-acetylmuramic acid (NAM). NAM and NAG are connected to each other with peptide bridges. Peptidoglycan is only in bacteria which makes it a key target for antibiotics.

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The cell wall in bacterial cells is very rigid and provides a stable shape to the cell. It is essential for bacterial growth and division. It is important in preventing the cell from bursting from osmotic pressure changes.

Cell Wall

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The cell wall cannot be observed through light microscopy or simple stains. It may be demonstrated by microdissection, reaction with specific antibodies, mechanical rupture of the cell, differential staining procedures or by electron microscopy.

Viewing the Cell Wall

The cell wall is composed of peptidoglycan, a mucopeptide (formed by N acetyl glucosamine & N acetyl muramic acid) linked to peptide chains. Teichoic acids are embedded into the cell wall and may be linked to lipids (Lipoteichoic acid). These Lipotechoic acids connect peptidoglycan to the cytoplasmic membrane and gives the cell wall its rigidity. 

Composition of the Cell Wall

Gram Positive vs. Gram Negative Bacteria

The outer membrane is only found in gram-negative bacteria and serves as the first barrier to the external surroundings. It is composed of lipopolysaccharides and phospholipids. 

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