Final answer:
Bacteria are surrounded by a cell wall composed of peptidoglycan and, in some cases, an additional outer membrane and capsule. This gives them shape, protection, and the ability to attach to various surfaces.
Step-by-step explanation:
Bacteria have a cell wall surrounding their cell membrane, which is primarily composed of peptidoglycan, a complex molecule made up of sugars and amino acids. This cell wall is critically important for providing structure, protection, and preventing dehydration. In addition to the peptidoglycan layer, some bacteria possess an outer membrane and may also have a polysaccharide capsule, contributing further to their ability to resist environmental stresses and adhere to surfaces. Gram-negative bacteria have a thinner peptidoglycan layer and a more complex cell envelope with an additional lipid bilayer known as the outer membrane, which is notable for containing lipopolysaccharides (LPS).