Bonding Structure of Peptidoglycan

Bacterial Cell Wall Structure 
Location and Amount of Peptidoglycan in 
Gram-positive vs. Gram-negative Bacteria


Peptidoglycan (pep-tid-o-gly-can) is a molecule found only in the cell walls of bacteria. The rigid structure of peptidoglycan gives the bacterial cell shape, surrounds the plasma membrane and provides 
with protection from the environment.

Article Summary: The amount and location of peptidoglycan in the prokaryotic cell wall is what determines whether a bacterium is Gram-positive or Gram-negative.
Bacterial Cell Wall Structure: Gram + & Gram -
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Prokaryotic Cell, Mariana Ruiz
Gram Positive Stained Staphylococcus Bacteria @ 1000xTM
Staphylococcus. Thick peptidoglycan cell wall retains crystal violet primary Gram stain. Go to > 
More Gram Stain Photos
Gram positive cell wall structure
Page last updated 8/2015

Peptidoglycan is a huge organic polymer of interlocking chains composed of similar monomers. The backbone 
Instructor's Corner
Continued ... 
Gram-negative Bacteria
Go to PAGE 2 >
Bonding Structure of Peptidoglycan
Gram-positive Cells
In Gram-positive bacteria, peptidoglycan makes up most (as much as 90%) of the thick cell wall.
of the peptidoglycan molecule is composed of two derivatives of the sugar glucose: NAG & NAM. 
Strands of NAG (N-acetylglucosamine) and NAM (N- acetylmuramic acid) are connected by interpeptide bridges.

See Page 2 for a diagram of the Gram-negative cell wall and a video on Gram Staining!

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