Here's why:

* Sugars: Peptidoglycan is made up of repeating units of two sugar derivatives: N-acetylmuramic acid (NAM) and N-acetylglucosamine (NAG).

* Peptides: These sugar units are cross-linked by short peptide chains, which vary slightly in their amino acid composition depending on the bacterial species.

Peptidoglycan is a crucial component of the bacterial cell wall, providing structural support and protection. It's unique to bacteria and is a target for many antibiotics.