PRCC Microbiology Practice Exam

The statement that the peptidoglycan backbones in gram-negative cells are linked by protein inter-bridges is false. In gram-negative bacteria, the structure of peptidoglycan is different from that in gram-positive bacteria.

In gram-positive bacteria, the peptidoglycan layer is thick and often has peptide inter-bridges that connect the glycan strands, which provides additional strength and rigidity to the cell wall. Conversely, in gram-negative bacteria, the peptidoglycan layer is much thinner and lacks these inter-bridges. Instead, the peptidoglycan is surrounded by an outer membrane composed of lipopolysaccharides and proteins.

This difference in cell wall structure is one of the key distinguishing characteristics between gram-positive and gram-negative bacteria, affecting their staining properties and susceptibility to antibiotics.