What does pink mean?

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Prepare for the PLTW Biomedical Science Test. Study with flashcards and multiple choice questions, each question comes with hints and explanations. Get ready for your exam!

Multiple Choice

What does pink mean?

Explanation:
In Gram staining, color after the final step tells you about the cell wall structure. Pink means the organism is Gram-negative. This happens because Gram-negative bacteria have a thinner peptidoglycan layer and an outer membrane. During decolorization with alcohol, they lose the crystal violet-iodine stain, and when you apply the counterstain, safranin, they appear pink. Gram-positive bacteria have a thick peptidoglycan layer that traps the violet stain and stay purple, while “Gram neutral” isn’t a standard result and “no stain” would mean no color at all. So pink points to Gram-negative bacteria.

In Gram staining, color after the final step tells you about the cell wall structure. Pink means the organism is Gram-negative. This happens because Gram-negative bacteria have a thinner peptidoglycan layer and an outer membrane. During decolorization with alcohol, they lose the crystal violet-iodine stain, and when you apply the counterstain, safranin, they appear pink. Gram-positive bacteria have a thick peptidoglycan layer that traps the violet stain and stay purple, while “Gram neutral” isn’t a standard result and “no stain” would mean no color at all. So pink points to Gram-negative bacteria.

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