Crime Scene Gel Electrophoresis - College of Science and ...

Crime Scene Gel Electrophoresis
Contributors
Michelle Carlson
Graduate Student
Georgia Southern University, GA
Partner Teacher
Donna Hanson
Partner Teacher
Bradwell Institute, GA
Intended Audience
K-4
5-8
9-12 X
Intended Audience
Classroom Setting X
Requires special equipment X
Uses hands-on manipulatives X
Requires mathematical skills
Can be performed individually
Requires group work X
Requires more than one (45 min class) period X
Appropriate for special needs student
Janee Cardell
MBI Program Coordinator
P.O. Box 8042
Statesboro, GA 30460
jcardell@georgiasouthern.edu
Crime Scene Gel Electrophoresis – Page 1

Introduction
Description
In this activity, students will get hands-on experience using gel electrophoresis to size separate
DNA fragments.
Abstract
Students will learn the concepts of gel electrophoresis, including electrical currents and size
separation of DNA fragments, through a made up scenario.
Students will get hands-on experience using micropipettes and gel electrophoresis boxes while
getting to visualize DNA on a gel.
Core Themes Addressed
Microbial Cell Biology
Microbial Genetics
Microorganisms and Humans
Microorganisms and the Environment
Microbial Evolution and Diversity
Other –Molecular Biology X
Keywords
DNA, Science and Technology, Pipette
Learning Objectives
At completion of this activity, students will be able to:
1. Demonstrate the ability to transfer liquid into wells.
2. Explain the uses of gel electrophoresis and how it works.
3. Describe the needed materials to run gel electrophoresis.
4. Identify the charge of DNA.
National Science Education Standards Addressed
Standard E: Science and Technology
Understandings about science and technology
Crime Scene Gel Electrophoresis – Page 2

Crime Scene Gel Electrophoresis – Page 3
Teacher Handout
Crime Scene Gel Electrophoresis
Student Prior Knowledge
The students need a background on how gel electrophoresis works and the reasons for its use and will
need to know how to use micropipettes to successfully load the gels.
Teacher Background Information
Micropipettors are standard laboratory equipment in micro and molecular biology laboratories. They are
used to measure and transfer small volumes of liquids.
Disposable plastic tips are placed on the end of the micropipettor for use in measuring liquids.
The plunger on top of the micropipette can be twisted to set the desired volume of liquid to be measured.
It also has two different stopping points when depressed. The first stopping point is used to measure out
the desired volume of liquid. The second stop is only used for the complete discharging of liquid from the
tips.
Micropipettes are expensive and certain rules should be followed.
Class Time
Never adjust the volume beyond the specific micropipettors range.
Always keep pipettes upright when liquid is in the plastic tip.
This activity will require a minimum of one and a half 90 minute class periods
DAY 1
DAY 2
1. Explanation of scenario (10 minutes)
2. Students “extract” DNA (5 minutes)
3. Students are taught about gel electrophoresis how it works and why it’s used
1. Load DNA into gels (10 minutes)
2. Run gel electrophoresis (30 min)
3. Fast blast stain (10 min)
4. Analyze gels (10 min)

Teacher Preparation Time
This lesson will require approximately 20 minutes of preparation time.
1. Teacher must know how to use a micropipette to teach students (10 minutes)
2. Make copies of handout (5 minutes)
3. Setup tubes with food coloring (5 minutes)
Safety Precautions
Safety goggles and aprons should be worn.
Materials and Equipment (4/ group)
Methods
1. Gel box (per 2 groups)
2. 10 mL agarose gel
3. Tube Rack
4. Box of pipette tips
5. micropipettor
6. 4 DNA samples
7. Power Box (per 2 groups)
8. 500 mL 1X TAE buffer
9. Plastic tray (for staining)
10. 50mL 5X FastBlast stain
1. The gel and the buffer have already been prepped and placed in the gel box.
2. Remembering correct pipetting procedures, add 5.0 µl loading dye to all 4 DNA
samples.
3. Pipette 10.0 µl of DNA into their appropriate wells using the figure above.
4. We will be running 2 gels to a box. Once both groups have loaded their DNA, place
the lid on the gel box. Do not hook up the power box until both groups have loaded
the DNA into their gels.
5. Make sure the power box is off and plugged into the outlet. Connect the black and
red wires to the appropriate outlets on the power box. Power on the gel box and make
sure the current is set to 100 V.
6. Once the box is turned on there should be bubbles rising on the sides of the gel box.
7. It will take some time before we can analyze the results (20 – 30 minutes). You need
to let the colored dye run ½ to ¾ of the way down the gel.
8. Once your DNA has migrated to an appropriate length, power down the power box
and remove the lid.
Crime Scene Gel Electrophoresis – Page 4

9. Using gloves remove the gel carefully and place it in the tray with the FastBlast stain.
Leave it in the stain until you begin to see bands. You can then compare each suspect
to the DNA left behind by the suspect.
Crime Scene Gel Electrophoresis – Page 5

Materials
Aquarium with dead
pet (rubber snake)
Crime Scene Gel Electrophoresis – Page 6
Scenario
Crime Scene Gel Electrophoresis
Bottle of poison (water with
a skull and cross bone)
Criminal’s hair left
at the crime scene
Ziplock bag
for evidence
Water dish
Fingerprint (4) 1.5 mL tubes Tweezers Ink pad Cue tips
Day 1 Crime scene setup:
Mrs. McCook and Mrs. Lewis have been fighting over the pet snake that they found abandoned on the
side of the road for weeks now. They both want to have it in their classroom and haven’t been able to
come to an agreement. It has recently been kept in Mrs. Baisden’s room until an agreement could be
made. This morning we found the snake and it had been poisoned. Left at the crime scene was a note that
said “If I can’t have him no one can have him”
We need to figure out who killed the pet snake?
Students can then be taken to the crime scene where they will collect evidence, (hair from criminal,
fingerprint, scales from snake)
Evidence must also be taken from suspects (Lewis and McCook)
DNA
Could use spit (water)
Skin cells (swab hand)
Hair
Student will then collect DNA from the different teachers. The DNA will be sent out for extraction at a
DNA lab. DNA banding patterns will include
1) Lambda DNA uncut (Suspect 1 and killer)
2) Lambda Hind III (Suspect 2)
3) Lambda EcoR I (Pet snake)
So the students can see what will be happening at the DNA lab they will then do a virtual DNA extraction
lab http://learn.genetics.utah.edu/content/labs/extraction/

Day 2: Gel electrophoresis
Students will be given different Suspects DNA and will micropipette loading dye and DNA
together.
Each student will get the chance to load a DNA sample into Agarose gel. The gels will be run in
a gel electrophoresis box in 0.25 TAE running buffer, stained using 5x fast blast stain, and then
dried down.
During the time it takes the gel to run a short power point on how gel electrophoresis and agarose
gel works can be given.
Materials:
- 1 gel box
- 1 10mL agarose gel
- 1 tube rack
- 1 box of pipette tips
- 1 micropipetter
- 4 DNA samples (Pet, CS, S1, S2)
- 1 power box
- 500 mL 1X TAE buffer
- 1 plastic tray (for staining)
- 50 mL 5X FastBlast stain
Procedure:
1. ____The gel and the buffer have already been prepped and placed in the gel box.
2. ____ Remembering correct pipetting procedures, add 5.0 µl loading dye to all 4 DNA
samples.
3. ____ Pipette 10.0 µl of DNA into their appropriate wells using the figure above.
4. ____ We will be running 2 gels to a box. Once both groups have loaded their DNA, place the
lid on the gel box. Do not hook up the power box until both groups have loaded the DNA into
their gels.
5. ____ Make sure the power box is off and plugged into the outlet. Connect the black and red
wires to the appropriate outlets on the power box. Power on the gel box and make sure the
current is set to 100 V.
Crime Scene Gel Electrophoresis – Page 7
Pet
CS‐ DNA from crime scene
S1 – Teaher 1
S2 – Teacher 2

6. ____ Once the box is turned on there should be bubbles rising on the sides of the gel box.
7. ____ It will take some time before we can analyze the results (20 – 30 minutes). You need to
let the colored dye run ½ to ¾ of the way down the gel.
8. ____ Once your DNA has migrated to an appropriate length, power down the power box and
remove the lid.
9. ____ Using gloves, remove the gel carefully and place it in the tray with the FastBlast stain.
Leave it in the stain until you begin to see bands. You can then compare each suspect to the
DNA left behind by the suspect.
Crime Scene Gel Electrophoresis – Page 8