Sentence Splitting: DNA Fingerprinting
Problem: How are DNA fingerprints made and interpreted?
Procedure: Our traits are all coded for by genes, which comprise segments of DNA. DNA fingerprinting is a process
which separates DNA into various gene segments, each of which is linked to our individual traits. In a process called electrophoresis, the larger fragments move more slowly through the gel than do smaller segments. The segments
are pulled through the gel by an electrical current. In this activity you will be carrying out a simulated electrophoresis
to better understand the DNA fingerprinting process.
q Begin by making a typed list of your personal traits. Follow the order of the list shown below.
Sex male or female
Eye color blue, brown, hazel, or green
Ear Lobes free or attached
Hairline widows peak or no widows peak
Little finger bent or straight
Chin dimples or no dimples
Tongue roller or nonroller
Skin freckles or no freckles
Your typed list should resemble a website address; no capital letters, all one word. For example:
malebluefreewidowspeakbentnodimplesrollernofreckles
q Neatly print your list on a strip of graph paper, placing one letter in each box. Proofread carefully, spelling is crucial
q Cut out your list of traits into one long narrow strip and trim the edges up to both ends of the list.
q Make cuts in your traits list between the following letters. This represents the work of restriction enzymes cutting the DNA at certain sites. It works best to mark all the sights for cutting first and then make your cuts
e-m z-a b-r e-n
t-t d-n g-h o-d
o-f 1-f n-r e-w
For example:
malebluefreewidowsneakbentno dimplesrollerno freckles
q Arrange the resulting strips on the sheet entitled Electrophoresis Gel Sheet according to the number of letters in each strip. Place each strip in the line with the corresponding number. If you have more than one segment with the same number of letters, place them as close together as possible.
q Turn the strips face down and glue or tape them in place.
q Compare the overall pattern of the segments with those of other students in class.
Summing Up:
1. What does the list of traits represent?
2. What does cutting the traits list represent?
3. Why are the cuts only made at certain points?
4. Explain why the segments are arranged the way they are.
5. How did your pattern compare with that of your classmates?
6. Explain any differences in patterns you found.
7. Why is this pattern referred to as a fingerprint?
8. Is the analogy to the fingerprint totally accurate? Why or why not?
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