In this episode of BioSpeak, we learn about the outer cell membrane, a unique and essential feature found in Gram-negative bacteria. Distinct from the universal plasma membrane, the outer membrane lies outside the peptidoglycan layer and is composed of lipopolysaccharides (LPS), which play a critical role in bacterial protection. The outer membrane functions as a protective barrier against toxic substances, including antibiotics, and houses various proteins like porins and efflux pumps that regulate the transport of molecules in and out of the cell. Additionally, the O-antigen polysaccharide of LPS helps bacteria evade the host’s immune response, making it a key factor in bacterial adaptability. By understanding the structure and function of the outer cell membrane, we gain insights into potential targets for antibiotic therapies against Gram-negative bacterial infections.