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This demonstration can be used to help learners visualize DNA by lysing (breaking open) bacterial cells on a slide and “stringing up” the DNA with a toothpick in less than one minute. This technique can also be used to study bacteria because only Gram-negative bacteria lyse in 3% KOH; Gram-positive bacteria do not. The technique is equivalent to the Gram-stain reaction, but does not require a microscope or potentially messy stains. This lesson guide includes instructions for two demonstrations, suggestions for modifications for advanced classes, study questions with answers for learners, and supplemental information and references.
- 1 to 7 days
- 5 to 10 minutes
- $10 - $20 per group of students
- Ages 11 - 18
- Activity, Demonstration, Experiment/Lab Activity, Lesson/Lesson Plan
- English
Quick Guide
Materials List (per group of students)
- plastic eggs, the hollow kind that open into two halves
- string or yarn
- chopsticks
- Culture plates of Gram-negative and Gram-positive bacterial isolates
- flat wooden toothpicks
- glass microscope slides
- dropper bottle containing 3% (w/v) potassium hydroxide (KOH)
Subjects
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Engineering and Technology
-
Engineering
- Bioengineering/Biomedical Engineering
-
Technology
- Medical Technology
- Agriculture and Biotechnology
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Engineering
-
Life Sciences
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Cells
- Cell Structure and Function
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Diversity of Life
- Viruses and Bacteria
- Classification
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Heredity and Genetics
- DNA Structure and Function
- Genetic Engineering
-
Human Body
- Medicine
-
Cells
-
Physical Sciences
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Chemistry
- Chemical Reactions
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Chemistry
-
The Nature of Science
-
The Scientific Process
- Conducting Investigations
- Formulating Explanations
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The Scientific Process
Audience
To use this activity, learners need to:
- see
Learning styles supported:
- Involves hands-on or lab activities
Other
Components that are part of this resource:
- Purpose and Background Information
- Materials and Methods
- Lesson Plan
- Supplemental Information and References
This resource is part of:
Access Rights:
- Free access
By:
- Schumann, Gail ; Jasalavich, Claudia A.
Rights:
- All rights reserved, The American Phytopathological Society, 2011