Final answer:
Small molecules or ions pass through channels called porins in the outer membrane of gram-negative bacteria. Porins enable the transport of essential molecules and ions while the LPS within the outer membrane contributes to the protective and toxic properties of these bacteria.
Step-by-step explanation:
The small molecules or ions pass through channels in the gram-negative bacterial outer membrane called porins. Porins are proteins that allow substances to pass through by forming pores in the outer membrane. They enable the transport of molecules and ions that are essential for the bacterial cell's survival and function.
In gram-negative bacteria, the outer membrane contains lipopolysaccharide (LPS), which consists of lipid A, core polysaccharide, and an O side chain. The LPS functions as an endotoxin and contributes to the pathogenicity of these bacteria, especially during infection and disease when it can induce a strong inflammatory response.
Porins are crucial as they provide a pathway for useful and necessary substances while still protecting the cell from harmful compounds, maintaining the integrity and selective permeability of the bacterial cell envelope.