In gram positive bacteria, the NAM molecules of peptidoglycan are linked with tetrapaptide links. These tetrapeptide molecules are not present in gram negative bacteria. In gram positive bacteria, the peptidoglycan later is much larger compared to gram negative bacteria. They also have a layer of teichoic acid on the external side of the plasma membrane which makes the wall more rigid.

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Types of Bacterial Cell Walls

Gram positive bacteria have a specific cell wall with a thick peptidoglycan layer. They have been identified from the Gram stain because of their cell wall retains the Gram stain. They have also been further classified by their genomes: 
- High G+C gram positive bacteria
- Low G+C gram positive bacteria

Gram Positive Bacteria

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Gram Positive Cell Walls

Gram negative bacteria have a thin layer of peptidoglycan. They also have an inner and outer membrane. The outer membrane contains the lipopolysaccharides which are important in gram negative bacteria being infectious. 

Gram Negative Cell Walls

The class *Actinobacteria* is also called the high G+C gram positive bacteria because their genomes have over 50% guanine and cytosine base pairs. While their class is very diverse in size and biomes they inhabit, one of their important features is that they have distinct and different peptidoglycans in their cell walls.

 High G+C gram positive bacteria: *Actinobacteria*

Low G+C gram positive bacteria have less than 50% cytosines and guanines their genomes. This group of bacteria also contains many pathogens. They consist of many different bacteria: 
- Clostridia
- Lactobacillales
- Bacilli
- Mycoplasmas 

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