Peptidoglycan (also called murein) is composed of alternating N-acetylglucosamine and N-acetylmuramic acid amino sugars joined by β-1,4 linkages with a short peptide composed ofl-alanine, d-glutamic acid, l-meso-diaminopalmelic acid, and d-alanine attached to the carboxyl group of the muramic acid. They are known to form a contiguous layer which envelopes the organism. Their protection stabilizes the cell by preventing bursting due to turgor and cell shape maintenance even when the organism divides and elongates.