What color do Gram-negative organisms typically appear after Gram staining?

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Study for the VTNE Laboratory Procedures Test. Use flashcards and multiple choice questions, each question offers hints and explanations, enabling increased understanding and retention. Prepare effectively for your exam!

Multiple Choice

What color do Gram-negative organisms typically appear after Gram staining?

Explanation:
Differential staining separates bacteria by cell wall structure, using a primary dye and a counterstain. The Gram stain first colors all cells purple with crystal violet, but during the alcohol decolorization step, Gram-negative bacteria lose this dye because of their thin peptidoglycan layer and outer membrane. They then take up the pink counterstain, so they appear pink/red. Gram-positive organisms, with a thicker peptidoglycan layer, retain the purple dye. Green and clear aren’t typical final colors in this stain. So, Gram-negative organisms typically appear pink.

Differential staining separates bacteria by cell wall structure, using a primary dye and a counterstain. The Gram stain first colors all cells purple with crystal violet, but during the alcohol decolorization step, Gram-negative bacteria lose this dye because of their thin peptidoglycan layer and outer membrane. They then take up the pink counterstain, so they appear pink/red. Gram-positive organisms, with a thicker peptidoglycan layer, retain the purple dye. Green and clear aren’t typical final colors in this stain. So, Gram-negative organisms typically appear pink.

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