Summer Research Program for Science Teachers
August 2004
Shereen Springer
Teachers Preparatory High School
Brooklyn, NY
How could we use kitchen electrophoresis to learn about gel electrophoresis?
The group activity in this lesson was taken from the website – colorful electrophoresis, Genetic Science Learning Center, at the University of Utah at http://gslc.genetics.utah.edu/units/activities/electrophoresis. It is such a great introductory activity that I had to include it.
Requires: Double Period Block (90 minutes)
Instructional Objectives: SWBAT
1. Explain the importance of electrophoresis as a separation technique
2. Explain the basic steps involved in electrophores
3. Explain the difference between passive transport and active transport
4. Identify which pure substance is located in a mixture based on the location of the bands
Materials:
For each group of students:
· Electrophoresis chamber, gel form and comb
· Electrophoresis power supply
· Agar gel
· Salt solution
· Commercial food colors or scientific stains
· Sample-loading device
· Masking tape, if needed to seal gel form
Mini Lesson: (20 minutes)
Do Now: Go to http://www.msu.edu/~russellr/portfolio/electrophoresis/electrophoresis.html
1. Read the section at the bottom of the page titled Basic concept of electrophoresis, then answer the following questions
A. How is electrophoresis similar to chromatography?
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B. How is electrophoresis different from chromatography?
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2. Now, click on the run gel button to simulate the process of electrophoresis.
As the gel runs, list any four observations.
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At this point I will ask a student to review the essential steps in the process, and any new vocabulary words learned.
Group Work (Activity): (55 minutes)
1. Preparation of the gel.
· Combine agar and water. Bring the mixture to a boil and heat until the agar is dissolved.
· Cool the agar until you can comfortably touch the flask.
· Place tape across the ends of the gel form (if needed) and place the comb in the form.
· Pour cooled agar into the form. The agar should come at least half way up the comb teeth.
· Immediately rinse and fill the agar flask with hot water to dissolve any remaining agar.
· When the agar has solidified, carefully remove the comb.
· Remove the tape (if used) from the ends of the gel form.
2. Loading the samples.
· Make a written record of which sample you will load in each well of the gel. You may find it helpful to load samples in every other well.
· Place the gel form on a black or dark surface to help you see the wells in the agar.
· Be careful not to puncture the bottoms of the wells as you load the samples.
3. Place the gel in the electrophoresis chamber.
· Make sure that the wells are closest to the negative (black) electrode.
4. Prepare the salt solution and add it to the chamber.
· Add salt to tap water and swirl to dissolve.
· Fill each half of the chamber, adding solution until it is close to the top of the gel. Gently flood the gel from the end opposite the wells to minimize sample diffusion.
5. Place the lid on the chamber and connect the electrode leads to the power supply.
· Connect the black lead to the negative terminal and the red lead to the positive terminal.
6. Turn on the power supply and adjust the voltage to 50-100 volts.
7. Run the gel for 5-10 minutes.
· Observe the samples separating into different colors.
8. Turn off the power supply, disconnect the electrode leads, and remove the chamber lid.
9. Remove the gel from the electrophoresis chamber and analyze your results.
· You may also remove the gel from the form and place it on a piece of plastic wrap.
· Place the gel on white paper to help you see the color separation.
· Record and evaluate the results of the electrophoresis.
10. Clean up.
· Discard the gel in the trash and pour the salt solution down the drain.
· Rinse the electrophoresis chamber and gel form with tap water. Turn them upside down to dry.
A student from each group will be asked to share with the rest of the class anything they learned by doing this activity, or any questions or concerns they may have.
Homework: Go to http://www.rit.edu/~pac8612/electro/E_Sim.html.
Run both electrophoresis simulations –electrophoresis of proteins and electrophoresis of DNA. State any obvious differences and similarities between these two processes.