What is the difference in the structure of the cell walls of gram-positive and grarn-negative bacteria?

The major difference between Gram-positive and Gram-negative peptidoglycan involves the thickness of the layers surrounding the plasma membrane. Whereas Gram-negative peptidoglycan is only a few nanometers thick, representing one to a few layers, Gram-positive peptidoglycan is 30–100 nm thick and contains many layers.

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the dark variety, as they are not visible on the dark tree barks

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