What distinguishes the cell wall of gram-positive bacteria from gram-negative bacteria?

The distinguishing feature of the cell wall in gram-positive bacteria is its thickness and its ability to retain the crystal violet stain during the Gram staining process. Gram-positive bacteria have a relatively thick peptidoglycan layer in their cell walls, which not only provides structural support but also traps the crystal violet dye, causing these bacteria to appear purple under a microscope after the Gram stain procedure.

This thick peptidoglycan layer makes the cell wall rigid and gives gram-positive bacteria unique properties, such as being more susceptible to certain antibiotics that target cell wall synthesis. In contrast, the cell wall of gram-negative bacteria is much thinner and is surrounded by an outer membrane, which is why they do not retain the crystal violet stain and instead appear pink after counterstaining with safranin.

The other options do not accurately describe the characteristics of gram-positive bacteria: they do contain peptidoglycan, which is essential for their cell wall integrity, and they do not lack a cell wall altogether. Therefore, the statement that highlights the thick cell wall which retains the crystal violet stain clearly distinguishes gram-positive bacteria from their gram-negative counterparts.