The document summarizes key differences between gram-positive and gram-negative bacterial cell structure. Gram-positive bacteria have a thicker peptidoglycan cell wall, while gram-negative bacteria have an additional outer membrane containing lipopolysaccharides. The gram staining method exploits these structural differences, resulting in gram-positive bacteria retaining the primary purple dye and appearing purple, and gram-negative bacteria decolorizing and appearing pink after a counterstain is applied. Some bacteria can also form dormant endospores to survive harsh conditions.