Final answer:
Bacterial cell walls are primarily composed of peptidoglycan, a mesh-like structure of sugars and peptides that is essential for cell shape and integrity, making it the target of many antibiotics. The composition varies between Gram-positive and Gram-negative bacteria, with differences in peptidoglycan thickness and the presence of an outer membrane.
Step-by-step explanation:
The primary component of bacterial cell walls is peptidoglycan, which consists of long chains of sugars combined with short peptide sequences that provide a rigid and protective mesh-like structure around the cell. Peptidoglycans are unique to bacterial cell walls and incorporate both L- and D-amino acids, making them distinct from the proteins usually found in most organisms, which only contain L-amino acids. This composition is essential to maintaining the shape and integrity of bacterial cells and is the target of many antibiotics that disrupt cell wall synthesis.
Differences exist between Gram-positive and Gram-negative bacteria in terms of the peptidoglycan's thickness and the presence of an outer membrane. Gram-positive bacteria have a thick layer of peptidoglycan, which retains the crystal violet dye used in the Gram staining method, while Gram-negative bacteria have a thinner layer of peptidoglycan and an additional outer membrane, which does not retain the dye.