Answer:cell wall
Explanation: bacteria are prokaryotes,they do not have membrane bound molecules.they are surrounded by rigid cell wall that gives them their shape.bacteria do not posses nuclear membrane.prokaryotes are either archaea or bacteria.
Bacteria have cell walls which are made up of peptidoglycan.peptidoglycan consists of polysaccharides interconnected with muramic acids.the sugar polymer is cross-linked by amino acids.this peptidoglycan gives the bacteria cell structure and shape.pennincillin Is an antibiotics that works by affecting the structure of the peptidoglycan,there by allowing water into the bacteria cell. This causes the bacteria to burst and die,there by reducing it's population