Final answer:
The difference in staining between Gram-positive and Gram-negative prokaryotes is due to their distinct cell wall compositions, with the former having a thick peptidoglycan layer and the latter having a thin layer plus an outer membrane.
Step-by-step explanation:
Prokaryotes stain as Gram-positive or Gram-negative because of differences in the cell wall composition. Gram-positive bacteria have a single, thick cell wall composed primarily of peptidoglycan, which is anchored to the cell membrane by lipoteichoic acid. In contrast, Gram-negative bacteria have a thinner layer of peptidoglycan surrounded by an outer membrane that contains lipopolysaccharides and lipoproteins. The presence or absence of this outer membrane is what differentiates Gram-positive from Gram-negative bacteria and influences their staining properties.