AAT Bioquest

What are the features of a gram-positive cell wall?

Posted February 22, 2024


A Gram-positive cell wall has the following features: 

  • In electron micrographs, a Gram-positive cell wall appears as a thick, dense wall with a thickness of about 20 nm – 80 nm. 
  • The Gram-positive cell wall contains a large amount of peptidoglycan, which makes up about 40% to 80% of the dry weight of the cell wall. The peptidoglycan is present as numerous interconnecting layers. It provides the cell with structural support and protection against the elements. 
  • Teichoic and teichuronic acids are interwoven in the Gram-positive cell wall. They play a role in preserving cell structure, antibiotic resistance, and cell division. 
  • There is no outer membrane outside of the peptidoglycan layer. Instead, the peptidoglycan layer is covered by a layer of lipids and proteins. 
  • A gelatinous material known as the periplasm lies between the peptidoglycan and the cytoplasmic membrane.
  • The cell wall stains purple when treated with Gram Stain. 
  • The thick peptidoglycan layer is more vulnerable to attack by drugs such as penicillin and cephalosporins.
Additional resources

Surface Proteins of Gram-Positive Bacteria and Mechanisms of Their Targeting to the Cell Wall Envelope

MycoLight™ Rapid Fluorescence Gram-Positive Bacteria Staining Kit

Gram Staining