Wolf Pack in a Bottle:
DNA Simulation with Paper Chromatography

Aleta Sullivan and JoAnne Dombrowski

Teacher instructions

An animal's genetic makeup can be analyzed using a technique called restriction mapping. In this process, strands of genetic material are first attacked by enzymes that cleave the DNA at specific sites. Next, the fragments resulting from this cleavage are sorted in a chromatography-like process called electrophoresis. If samples from two organisms contain a similar assortment of DNA fragments, then the organisms are closely related. If fragment concentrations in samples are dissimilar, the organisms are less related, and these are the animals needed to strengthen the breeding program. In this activity, you will perform an experiment that models this type of DNA analysis.

Lab Notes: This activity can be performed by individuals or in groups. Make five mock DNA solutions using food coloring; three should be similar and two dissimilar. Each group or individual should have one sample of each of the five solutions.

Suggested Solutions:

Solution 2: equal amounts blue, red

Solution 3: equal amounts red, yellow, and green

Solution 4: equal amounts red, yellow, and green

Solution 5: two parts blue, one part green

(Teacher Answer to Problem: Solution 2 provides the most genetic variation, and represents the animal best for the breeding program.)

Answers to Student Questions:

2. DNA fragments have different weights and move at different speeds in electrophoresis.

3. and 4. Answers will vary.

5. Like solutions of DNA fragments, the food-coloring solutions separate into components. Similarities and differences in the components are then used to classify the solutions. Solutions that show similarities are analogous to restriction mapping of closely related species; dissimilar solutions represent distant relations.

6. Answers will vary depending upon setup, but the best wolf is represented by teacher Solution 2.

7. Introducing two different subspecies may provide genetic variety. The hoped-for outcome is a wolf pack in which genetic variety may insure species survival.

Extensions

Additional WOLF materials available through your state Project WILD Coordinator.

Procedure:

1. Gather your supplies and samples. Observe the samples and predict which one will be the best wolf (the most different). Answer on your data sheet.

2. Cut filters 10 cm wide and 10 cm long. Fold paper so that it will stand in container (see diagram).

3. Draw a pencil line about 2 cm above the lower edge of the filter paper. Mark five locations on the line, evenly spaced, and number these locations below the line.

4. Using a new toothpick for each solution, transfer mock DNA Solutions 1-5 to marked locations. Let the solutions dry.

5. While filter paper dries, pour about 1 cm of water into the container.

6. Position the folded filter paper in the water container so that the treated end is in contact with the water (the dots should be about 1 cm above the surface of the water).

7. After 15 minutes, examine the paper. Compare your samples of DNA Solutions 1-5. Then compare your samples with others in your class.

8. Answer question on Data Sheet.

Name

Period

Class:

Questions

CONSIDER THIS!

It is estimated that more than 99% of the species ever living on Earth are now extinct. How much should people do to preserve living species?



Should endangered species always be rescued, despite the risks? Who should determine which species are saved?



Why is inbreeding a serious problem? How has inbreeding affected the cheetah?



Are there any endangered species in your area which might benefit from this breeding program?

On to The Electrophoresis
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