DNA FINGERPRINTING SIMULATION
Name: ____________________________________
Date: ________________________ Per: _______
Background:
Every person shares approximately 99.9% the same DNA. But the 0.1% that is different
plays an important role in making us who we are. Because one in every 1000 bases is
different, scientists can create a DNA Fingerprint. Instead of an inky image of our actual
fingers, DNA Fingerprints show us a bar code of our DNA. Restriction Enzymes cut our DNA
in specific locations chopping it into smaller strands of various sizes. The cut-up DNA is
then put through Gel Electrophoresis, which separates the pieces by size (smaller pieces
move farther faster). From this image, we can identify mutilated bodies, criminals, and
parents. In this lab, we will make a DNA Fingerprint from a small sample of DNA.
Procedure:
1. Cut out the four strands of DNA from Template 1 and Template 2.
2. Attach the four small strands with a little bit of glue to make one longer molecule of
DNA.
3. Down one side of the DNA Helix you can make a completely random chain of letters.
4. Down the other side, you should put in the complimentary bases. Remember that A
= T and C = G.
5. Now that we have a personal piece of DNA, we will cut the molecule with 3
Restriction Enzymes. Each enzyme cuts the DNA at a specific location. You will go
down the strand and cut your DNA after the last letter of the enzyme.
a. Restriction Enzyme #1 - TCTAT
b. Restriction Enzyme #2 – GGAA
c. Restriction Enzyme #3 – ACC
6. Now that we have digested our DNA molecule with Restriction Enzymes, we will
simulate a Gel Electrophoresis. The actually process pulls the DNA fragments
through a semi-solid gel with electricity (negatively-charged DNA moves towards a
positive pole).
a. In our example, we will count the number of base pairs in each fragment.
b. For each fragment, shade in the box that corresponds to its length.
c. If the DNA did not get cut, simply shade the top box.
7. Copy the DNA fingerprints for three of your classmates.
Gel Electrophoresis
DNA Fragment Size
43-44 Base Pairs
40-42 Base Pairs
37-39 Base Pairs
34-36 Base Pairs
31-33 Base Pairs
28-30 Base Pairs
25-27 Base Pairs
22-24 Base Pairs
19-21 Base Pairs
16-18 Base Pairs
13-15 Base Pairs
10-12 Base Pairs
7-9 Base Pairs
4-6 Base Pairs
1-3 Base Pairs
Discussion Questions:
1. How is DNA Fingerprinting similar to an actual fingerprint?
2. What is the underlying principle explaining why DNA Fingerprinting works?
3. How can we use DNA Fingerprints?
4. What is the role of the Restriction Enzymes in this process?
5. What is the role of the Gel in this process?
6. How are the DNA fragments separated?
7. Why do you and your partners have different DNA fingerprints?
8. What would it mean if two people had several bars in the same places?
9. What would it mean if two species had several bars in the same places?
10. Using the Paternal DNA Fingerprint below, identify the father of the child.
Explain your answer.