What component is present in gram-negative cells but absent in gram-positive cells?

In gram-negative cells, the presence of lipopolysaccharide (LPS) is a defining characteristic that differentiates them from gram-positive cells. LPS is a complex molecule composed of a lipid portion known as lipid A, a core oligosaccharide, and an O-antigen polysaccharide chain. It serves multiple critical roles, including contributing to the structural integrity of the bacterial outer membrane and acting as an endotoxin when released into the host.

The presence of LPS provides gram-negative bacteria with protection against certain antibiotics and detergents, as well as being a significant factor in the immune response elicited during infections, often leading to fever and other symptoms due to its ability to trigger a strong inflammatory response. This molecule is a key factor in the pathogenicity of many gram-negative bacteria and influences how they interact with their environment, including host organisms.

In contrast, components like peptidoglycan, teichoic acid, and protein A are found in gram-positive bacteria. Peptidoglycan, while present in both gram-negative and gram-positive cells, differs in its thickness and structure, with gram-positive cells containing a much thicker layer. Teichoic acids are specifically associated with the cell walls of gram-positive bacteria and are not