What are gram-negative bacteria?
Q: What are gram-negative bacteria?
A: Gram-negative bacteria are a type of bacteria that do not retain the crystal violet dye in staining.
Q: How are gram-negative bacteria identified in a Gram stain test?
A: In a Gram stain test, a counterstain called safranin is added after the crystal violet dye. This colours all gram-negative bacteria with a red or pink colour.
Q: Why do gram-negative bacteria stain red or pink in the Gram stain test?
A: Gram-negative bacteria stain red or pink because an outer membrane stops the penetration of the crystal violet dye.
Q: What makes gram-negative bacteria more resistant against antibiotics?
A: Compared with gram-positive bacteria, gram-negative bacteria are more resistant against antibiotics because of their relatively impermeable cell wall.
Q: What is the significance of the lipopolysaccharide layer in gram-negative bacteria?
A: The lipopolysaccharide (LPS) layer in gram-negative bacteria is important because it triggers an innate immune response in humans, with cytokine production and immune system activation.
Q: What is the result of cytokine production triggered by LPS in humans?
A: The result of cytokine production triggered by LPS in humans is inflammation.
Q: What is the usefulness of the Gram stain test?
A: The Gram stain test is useful in classifying two distinct types of bacteria based on the structural differences of their bacterial cell walls.
