SIMPLE STAIN AND NEGATIVE STAIN POST LAB QUESTIONS
1. Explain why a simple stain colorizes the cells while a negative stain does not.
2. Sometimes you can stain with both a simple stain and a negative stain at the same time. If I stained a smear of Bacillus subtilis with both safranin (pink) AND nigrosin (dark purple/black negative stain) what would I expect to see on the slide? Draw me a picture. Be sure to address the shape of the bacteria in your drawing.
3. How about a smear of Streptococcus pyogenes with crystal violet (purple)? Draw a picture. Be sure to address the shape and arrangement of the bacteria in your drawing (we didn’t look at this one, you can tell the shape and arrangement from the name).
4. How about a smear of Staphylococcus aureus with Congo red? Draw a picture. Be sure to address the shape and arrangement of the bacteria in your drawing.
