Question

A student creates a Gram stain on a bacterial sample that has a mix of gram-negative and gram-positive organisms. The student accidentally forgets the decolorizer step. What would the outcome of the Gram stain be?
A. The Gram stain would show pink (gram-negative bacteria) and purple (gram-positive bacteria).
B. All organisms would appear purple (gram-positive).
C. All organisms would appear colorless.
D. All organisms would appear pink (gram-negative).

Answer 1

Answer:

The correct answer is B.  All organisms would appear purple (gram-positive).

Explanation:

Gram staining is done to differentiate between gram positive and gram negative bacteria. Gram positive bacterial cell wall is made up of peptidoglycan which dehydrates and shrinks after decolorizing step and large crystal violet and iodine complex do not comes out making them purple in this process.

But in gram negative bacteria the cell wall is made up of lipids in which the crystal violet-iodine complex comes out due to the degradation of lipid by decolorizer.

So when the student forgot to decolorize bacterial sample crystal violet do not comes out from gram negative cell wall making them purple like gram positive cells. So all organism will appear purple.