After performing the Gram stain, Gram-positive bacteria appear as which color?

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Multiple Choice

After performing the Gram stain, Gram-positive bacteria appear as which color?

Explanation:
Gram staining differentiates bacteria by cell wall structure. The crystal violet-iodine complex is trapped in the thick peptidoglycan layer of Gram-positive cells, so it remains purple after the decolorization step. That’s why Gram-positive bacteria appear purple under the microscope. In contrast, Gram-negative bacteria have a thinner peptidoglycan layer and an outer membrane, so they lose the purple and take up the pink counterstain.

Gram staining differentiates bacteria by cell wall structure. The crystal violet-iodine complex is trapped in the thick peptidoglycan layer of Gram-positive cells, so it remains purple after the decolorization step. That’s why Gram-positive bacteria appear purple under the microscope. In contrast, Gram-negative bacteria have a thinner peptidoglycan layer and an outer membrane, so they lose the purple and take up the pink counterstain.

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