Bacterial cell walls are composed of peptidoglycan, a complex polymer of sugars and amino acids. Peptidoglycan forms a mesh-like structure that surrounds the cell membrane and provides the cell with its rigid shape and structural integrity.

Here's a more detailed breakdown:

* Sugars: Peptidoglycan is made up of two alternating sugars: N-acetylmuramic acid (NAM) and N-acetylglucosamine (NAG).

* Amino Acids: These sugars are linked together by short chains of amino acids, forming a "peptide" bridge.

* Structure: The NAM and NAG units are linked together to form long chains that are cross-linked by the peptide bridges, creating a strong, rigid, and supportive network.

There are two main types of bacterial cell walls, distinguished by the thickness of their peptidoglycan layer:

* Gram-positive bacteria: Have a thick peptidoglycan layer, making them stain purple in a Gram stain. They also have other molecules like teichoic acids embedded in their cell wall.

* Gram-negative bacteria: Have a thin peptidoglycan layer, making them stain pink in a Gram stain. They have an outer membrane composed of lipopolysaccharide (LPS) that surrounds the peptidoglycan layer.

The bacterial cell wall is essential for bacterial survival. It protects the cell from osmotic lysis (bursting due to internal pressure), provides structural support, and plays a role in cell division.