1. Activity 9
DNA Isolation

2. Read the introduction. (p. 328)
What is DNA?
Deoxyribonucleic acid (DNA)
is a molecule that makes up
genes, present in every living
organism.

3. Where is DNA in each of these cells?
Three Types of Cells
Where is DNA in each of these cells?
Ask the students, Where is DNA located in each of these cells? For more information on having this class discussion, and a suggested demonstration, see the Teacher’s Edition for this activity.
These images are from Transparency 9.1, “Three Types of Cells.”
Bacteria Cell
Plant Cell
Typical Animal Cell

4. How could you isolate DNA from an organism’s cell?
Challenge
How could you isolate DNA from an organism’s cell?

5. Lysis is the process of breaking cells apart.
Need a source of DNA
Lysis is the process of breaking cells apart.
Precipitation occurs when a dissolved substance is made insoluble, usually by adding a chemical. The substance becomes a solid and precipitates out of the solution.
As student groups summarize the isolation steps on Student Sheet 9.1, “DNA Isolation Procedure,” clarify the purpose of each step and the equipment. Introduce the key concepts on the slide. For more information on having this class discussion and a sample student response for Student Sheet 9.1 see the Teacher’s Edition for this activity.
Procedure Step 2 is an opportunity to apply the Group Interaction (GI) Scoring Guide to assess students’ group interaction skills. For more information see the Teacher’s Edition for this activity and Teacher Resources IV: Assessment.

6. Complete Analysis p. 327 (1-2-4-5)
Analysis 1: What is the purpose of mashing the sample in the plastic bag? Breaks down the cell & nuclear membranes

7. Analysis 2
Describe the purpose of the lysis solution & the DNA precipitation solution
Lysis solution: (salt & detergent)…breaks down the cell & nuclear membrane
Precipitaiton solution (alcohol)…caused the DNA to clump together

8. Analysis 4
Compare the properties of DNA isolated from different organisms. What similarities did you observe?
Similar in color & consistency

9. Analysis 5
How is the mechanism for isolating DNA from an organism connected to the mechanism for genetically modifying that organism?
DNA must first be isolated before it can be removed & placed into another organism
DNA isolation is an essential step in the genetic engineering of an organism. See the Teacher’s Edition for this activity for more information and a sample student response.