MacGyvering Gel Electrophoresis: a
Research-based Lab
Lacey Howard
Shearer Lab Research Group
Sumrall High School Biology I Students
Sorrell: 1st block 30, 3rd block 20
Hummell: 3rd block 21
5 E’s of the Lesson Plan
1. Engage- ask students to discuss their knowledge of gel
electrophoresis.
2. Explore- have the students practice using pipettors
with a scale and water.
3. Elaborate- have the students perform their own gel
electrophoresis experiment.
4. Explain- discuss the principles of gel electrophoresis
and how it is used in my research.
5. Evaluate- have the students fill out lab worksheets
with data results and summary questions.
State and National Subject Content
• Science as Inquiry
– Using the scientific method
• Science and Technology
– Distinguish and explain the applications of various
tools and techniques used in DNA manipulation
– Steps in genetic engineering experiments
– Use of restriction enzymes
• Science in Personal and Social Perspectives
– Explain uses of technology in paternity testing and
crime scene evaluations.
• Unifying Concepts and Processes
Materials Required
Each gel electrophoresis kit needs:
• Five 9 V batteries connected in series
• Two alligator clips with one red wire and one
black wire
• Small Tupperware with two holes on either
end
• Two wires bent through holes in Tupperware
and connected to alligator clips
Additional Materials
• 1X TAE buffer (Tris base, Acetic acid, EDTA) or 1x TBE
buffer (Tris base, Borate, EDTA)
• Agarose
• Loading Dye
• Ethidium Bromide
• Safety glasses
• UV light
• Surgical gloves
• DNA
• Erlenmeyer flask
• Microwave
What is gel electrophoresis?
• Gel electrophoresis is a technique that
separates pieces of DNA (or other biological
molecules) by size so researchers can analyze
them.
How does gel electrophoresis work?
- Electrode
Wells for DNA samples
- Electrode
+ Electrode
Side View
+ Electrode
Top View
Agarose gel with Ethidium Bromide
Staining
DNA
Ladder
Larger DNA Fragments
Smaller DNA Fragments
Molecular Weight Marker
• A mixture of different pieces of DNA of known
size used to determine the size of fragments in
the sample.
Staining
• DNA in the gel is invisible.
• To visualize DNA, gels are stained with ethidium
bromide.
• A UV light is then used to visualize the EtBr.
CAUTIONS:
• Ethidium Bromide is a carcinogen.
–
–
–
–
–
wear gloves
correct disposal
UV light damages eyes
wear goggles
use photoimaging system
Ethidium bromide
•
Ethidium bromide has a ring structure similar to the ring
structure in DNA bases; therefore it intercolates between the
bases.
• Shining UV light on ethidium bromide will cause it to fluoresce
at visible wavelengths.
Loading Dye
• Purposes
– give color to sample
– give weight to sample so it will sink into well
– show progress of gel migration
• Components
– dyes (xylene cyanol, bromphenol blue,
Orange G) weight (glycerol or ficoll)
Uses of DNA Gel Electrophoresis
•
•
•
•
•
Is DNA present in sample?
Is a PCR product present?
Is the PCR product the correct size?
Where in the DNA do specific enzymes cut?
Also, a specific DNA fragment can be
recovered from the gel.
Gel Electrophoresis Start to Finnish
Biology I Students Performing
Electrophoresis
Changes for the Future
• This lab requires at least an hour of preparation time.
• To minimize the time students are waiting for the
experiment to run without having work to do, give the
lecture while the experiment is running.
• Explain more about PCR and restriction enzymes
during the lecture.
• Engage students by talking about processes they see on
crime scene shows like paternity testing and DNA
evidence.
• Go over proper pipetting technique and aseptic
technique before lab experiment.
References
• Desktop electrophoresis lab- moving
molecules
http://www.accessexcellence.org/AE/WWC.19
93/moving.php
• DNA gel electrophoresis
http://www.colorado.edu/Outreach/BSI/pdfs/
Electrophoresis%20Notes.pdf
Q&A