Gram staining is a common method of distinguishing bacteria.It takes advantage of the thickness of the peptidoglycan layer in the cell wall.What type of bacteria appear red after staining with a secondary dye?
A)Gram negative
B)Gram positive
C)Gram neutral
D)Gram prokaryotic

Question

Quizplus · Accepted Answer

Gram negative bacteria have a thinner peptidoglycan layer in their cell wall, which allows the secondary dye (safranin) to penetrate the cell and stain it red/pink. Gram positive bacteria have a thicker peptidoglycan layer, which retains the initial crystal violet stain and appears purple.

Gram Staining Is a Common Method of Distinguishing Bacteria