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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Staphylococcus. Thick peptidoglycan cell wall retains crystal violet primary Gram stain. Go to >
Peptidoglycan is a huge organic polymer of interlocking chains composed of similar monomers. The backbone
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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