Question

The main difference between Gram-positive and Gram-negative bacteria is

• A. Cell membrane
• B. Cell wall
• C. Ribosome
• D. Mitochondria

Answer 1

The correct option is B Cell wall

In Gram staining, the bacterial cell wall is stained with crystal violet. The cells are then washed with absolute alcohol or acetone. Gram positive bacteria retain the purple colour. Gram negative bacteria have a high lipid content in their cell walls. Hence, the crystal violet stain is washed away. They are then counterstained with safranin.