In Gram-positive bacteria, bacteriocins form ______ in the cell membrane.

• A. Channels
• B. Pores
• C. Patches
• D. Membrane pits

Answer: (B)

Bacteriocins kill rival cells by inserting into the target cell’s membrane and assembling into pore-forming structures. These pores create openings that let ions and small molecules leak across the membrane, dissipating the proton motive force and ATP synthesis, which leads to cell death. In Gram-positive bacteria, the membrane is directly accessible because there’s no outer membrane, so these peptide toxins can readily form such pores in the cytoplasmic membrane. This pore formation is the best way to describe their action, more precise than calling them channels or other terms, since the key effect is creating openings that disrupt membrane integrity and ion balance.