Today we learned about gram staining in my microbiology lab. The cell walls of different bacteria determine how well the stain will adhere and thus determine the color. Gram positive bacteria have a cell wall with a thick layer of peptidogylcan and stains love them, but gram negative bacteria have thin layers of peptidogylcan with an extra lipopolysacarrhide outer member and don't take stain well (this alps makes them more resistant to certain antibiotics). It's important as a doctor to know which type of bacteria your patient might be infected with in order to treat the condition properly!