cellTRAY® Science Kit

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Lesson Plans:
Cell Staining Science Kit - Middle School
Cell Staining Science Kit - High School
Related Products:
cellTRAY Dish

Product Q & A Forum

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Submitted by
D. Keating
Q: We are not able to use cheek cells in our classroom. Does the cellTRAY Science Kit work on any non-cheek cells?
A: YES. The cellTRAY Science Kit is equally effective using hand skin cells. Please download the lesson plan and use the information provided on the second page.
Submitted by
R. Thompson
Q: What are the primary differences between the stains that can be used in cell staining experiments?
Trypan Blue (which we include in our cellTRAY Science Kit for Teachers) stains nucleic acids but is toxic to cells. This stain is used to selectively differentiate live and dead cells; live cells will actively pump the stain out (will not stain) while dead cells will stain blue. Staining experiments with Trypan Blue are commonly used in laboratories and clinics to determine the ratio of live and dead cells. Our Science Kit uses Trypan Blue so that students can observe live and dead cells in a single experiment while also observing the cell structure. Methylene Blue also stains nucleic acids but requires that you “fix” the cells onto the slide; the use of Trypan Blue does not require this step. Since the Methylene Blue stain is very dark, cells must be de-stained in order to view them under a microscope. Our multi-step experiment instructions demonstrate cell fixing, staining, and de-staining using either Methylene Blue or Trypan Blue. Iodine (or Lugols Solution) stains starch. Plant cells synthesize starch. Onion cells or any other plant cells will stain with iodine but animal cells will not stain. Since both plant and animal cells contain DNA, they will stain with Methylene Blue; however, you need to disrupt the plant cell wall first by de-hydrating the cells with 100% alcohol, stain with diluted Methylene Blue, and then de-stain with water. Gram Stains is typically used to categorize bacteria into 2 groups (gram positive or negative) due to the differences in their cell wall structure. Generally, gram positive bacteria, such as those found in yogurt (Lactobacillus and Streptococcus) are less pathogenic. Their cell walls can be disrupted with penicillin or with lysozyme (an enzyme that our cells are able to produce). Gram negative bacteria, such as E.coli, Helicobacter, and other bacteria of the stomach, are more pathogenic. Gram negative bacterial cell walls are composed of lipopolysaccharides that can be an endotoxin (toxic shock syndrome). Gram stain experiments are another type of a multi-step staining and de-staining experiment.

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