Sentence Splitting: DNA Fingerprinting
By David Millis
Edgewood-Colesburg High School
403 W. Union
PO Box 316
Edgewood, Iowa 52042
Lab Written through the BIOMES project
Director Jody Stone Stone@uni.edu
University of Northern Iowa
Sentence Splitting: DNA Fingerprinting
Concept Development
BIOMES Topic: DNA - Electrophoresis, Biotechnology
Lab setup:
Lab time required:
Reasoning level:
Process skills:
Web Connect:
National Standards:
none
15-30 minutes
easy
collecting data
yes
Life Science molecular basis for
heredity
easy
30-45 minutes
moderate
comparing
no
moderate
difficult
45-60 minutes
60-90 minutes
difficult
interpreting data utilizing models
Objectives: Create a DNA fingerprint model based on your individual traits.
Materials: Access to a word processor is essential. If classroom computers are not available, have students
generate their traits list during class and type it as a homework assignment. The size of the strips that contain
the traits list should be uniform for all students for comparison purposes. Sixteen point font size and Times New
Roman type style are suggested.
Teaching Strategies:
For this activity, you may choose to provide verbal directions, rather than printing copies of the student
page. "Summing Up " questions could then be listed on the chalkboard or on an overhead. Introduce the activity
by assigning the traits list first, asking each student to make their own individual list of traits according to the
parameters that make the lists uniform. The students need to be aware that this list corresponds to the list of
instructions that caused them to have those traits in the first place. These instructions are found in the DNA.
When the students cut their list at certain places, this is like a restriction enzyme cutting their DNA. When the
segments are spread out, they are separated according to the rules of electrophoresis, larger fragments moving
more slowly than smaller fragments. The data sheet is delineated in order to simplify the distribution of the
fragments. You may want to point out to students some general points about electrophoresis patterns and why
fragments of differing size are placed differently. Later on in the activity, students place the segments face
down. This is designed to lead students to the realization that the pattern of fragments are determined by their
relative length, not by their actual sequence.
Sample Data and Observations:
Each student should have a completed electrophoresis sheet containing their pattern. See Sample Data Sheet
Sample Responses to Summing Up:
1. The list of traits represent the genetic code for those traits made up of sequences of DNA.
2.
The cutting of the traits list represents the action of restriction enzymes cutting DNA.
3. Cuts are made only at certain points because restriction enzymes recognize and cut DNA only at certain
sequences. There are 10 restriction sites representing the work of 10 different restriction enzymes.
Sentence Splitting: DNA Fingerprinting
Concept Development
Problem: How are DNA fingerprints made and interpreted?
Materials: scissors
electrophoresis gel template
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. In this activity you will be carrying out a
simulated electrophoresis to better understand the DNA fingerprinting process.
>

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 non-roller
Skin - freckles or no freckles
Your typed list should resemble a website address; no capital letters, all one word. For example:
malebluefreewidowspeakbentnodimplesrollernofreckles

Type your list using a size 16 font. Proofread carefully, spelling is crucial

Cut out your list of traits into one long narrow strip and trim the edges up to both ends of the list.

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
t-t
o-f
z-a
d-n
1-f
b-r
g-h
n-r
e-n
o-d
e-w
For example:
malebluefreewidowsneakbentno

dimplesrollerno
freckles
•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.

• Turn the strips face down and tape them in place.

• 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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GEL ELECTROPHORESIS SHEET - Sample Data Sheet
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
8 -------------------------------------------------- freckles ----------------------------------------------------9 -----------------------------------------------------------------------------------------------------------------10 ----------------------------------------------------------------------------------------------------------------11 ----------------------------------------------------------------------------------------------------------------12 ----------------------------------------------------------------------------------------------------------------13 ----------------------------------------------------------------------------------------------------------------14 ----------------------------------------------------------------------------------------------------------------15 ----------------------------------------------dimplesrollerno -----------------------------------------------16
17
18
19
20
21
22
23
24
25
26
27
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
28 ------------------------------------ malebluefreewidowspeakbentno -----------------------------------29 ----------------------------------------------------------------------------------------------------------------30 ----------------------------------------------------------------------------------------------------------------31 ----------------------------------------------------------------------------------------------------------------32 ------------------------------------------------------------------------------------------------------------------
GEL ELECTROPHORESIS SHEET
1 ---------------------------------------------------------------------------------------------------------------------------------2. ---------------------------------------------------------------------------------------------------------------------------------3 ---------------------------------------------------------------------------------------------------------------------------------4 ---------------------------------------------------------------------------------------------------------------------------------5 ---------------------------------------------------------------------------------------------------------------------------------6 ---------------------------------------------------------------------------------------------------------------------------------7 ---------------------------------------------------------------------------------------------------------------------------------8 ---------------------------------------------------------------------------------------------------------------------------------9 ---------------------------------------------------------------------------------------------------------------------------------10 -------------------------------------------------------------------------------------------------------------------------------11 -------------------------------------------------------------------------------------------------------------------------------12 -------------------------------------------------------------------------------------------------------------------------------13 -------------------------------------------------------------------------------------------------------------------------------14 -------------------------------------------------------------------------------------------------------------------------------15 -------------------------------------------------------------------------------------------------------------------------------16 -------------------------------------------------------------------------------------------------------------------------------17 -------------------------------------------------------------------------------------------------------------------------------18 -------------------------------------------------------------------------------------------------------------------------------19 -------------------------------------------------------------------------------------------------------------------------------20 -------------------------------------------------------------------------------------------------------------------------------21 -------------------------------------------------------------------------------------------------------------------------------22 -------------------------------------------------------------------------------------------------------------------------------23 -------------------------------------------------------------------------------------------------------------------------------24 -------------------------------------------------------------------------------------------------------------------------------25 -------------------------------------------------------------------------------------------------------------------------------26 -------------------------------------------------------------------------------------------------------------------------------27 -------------------------------------------------------------------------------------------------------------------------------28 -------------------------------------------------------------------------------------------------------------------------------29 -------------------------------------------------------------------------------------------------------------------------------30 -------------------------------------------------------------------------------------------------------------------------------31 -------------------------------------------------------------------------------------------------------------------------------32 --------------------------------------------------------------------------------------------------------------------------------