Book Definitions
Gram Stain: A differential stain that distinguishes between cells that possess a thick cell wall and retain a positively-charged stain (gram-positive) from cells with a thin cell wall and outer membrane that fail to retain the stain (gram-negative)
~ Gram-negative bacteria: bacteria that fail to retain the Gram stain because they have a thin cell wall.
~ Gram-positive bacteria: Bacteria that retain the Gram stain by virtue of their thick cell wall reinforced by teichoic acids