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FAQ for Forensic Science: Building Your Own Tool...

Posted: Fri Dec 23, 2011 10:06 am
by amyc
The following FAQ contains frequently asked questions and answers about the Forensic Science: Building Your Own Tool for Identifying DNA project. If you are having trouble with the procedure, you may find assistance in the answers below.

Q: How can I keep the dyes from running together?
A: Don't worry if you are having difficulty loading the dye into the well – even experienced scientists find this step hard! If after a few tries you are still having trouble, try one or both of the following:

  • Only use every other well. If you created 5 wells, use wells 1, 3 and 5, and leave 2 and 4 empty. If 'there is more distance between the dyes, it will be harder for them to run together.
  • Use a plastic pipette to put the dye in the wells. A pipette is similar to an eyedropper, but smaller, so it is easy to put it directly into the well and only squeeze out a drop or two of dye.

Q: The Styrofoam comb didn't create good wells in the agarose gel. What else can I use?
A: Styrofoam is the easiest material to use when forming the comb because it is easy to cut. However, if you are having trouble forming the wells with a Styrofoam comb, cardboard makes an appropriate substitute.

Q: What would be a testable question or hypothesis for this project?
A: A large part of this experiment is constructing the electrophoresis chamber. Since you can run electrophoresis on multiple samples at once, you might want to try a question and hypothesis based on comparing different samples or dyes. Remember, you should always be able to test your hypothesis and have good evidence to support or refute it. For additional information about constructing a hypothesis, view this Science Buddies resource:

Q: What if there is no bubbling at the electrodes?
A: When you attach the power source, electricity should run through the alligator clips to the electrodes, and you should see bubbling, particularly at the positive electrode (the one farther from the food dyes). If you aren't seeing bubbling, double check your configuration. Make sure everything is connected well and that you have the correct leads connected to the correct electrodes. If you still don't see any bubbling, make sure your batteries are working and are connected together correctly.

Q: Where can I reorder more agarose?
A: The materials list for this Project Idea lists Bio-Rad as a source for purchasing agarose. Science Buddies also maintains a list of "Approved Vendors," many of which carry agarose ( If you have any questions about whether or not you are purchasing the right agarose product, please post your question in this forum.

Q: I'm having trouble creating the gel. What might be going wrong?
A: There is a great video that the 2011 Science Buddies Summer Fellows put together, which demonstrates the procedure used in this Project Idea. You can view this video on the Project Idea page or at YouTube:

If you have other questions about the procedure or need assistance troubleshooting your gel or the Experimental Procedure, please post your question in the forum for this kit at Ask an Expert: Our team of volunteer Experts is available to assist. We attempt to reply to questions within 24 hours. Please note that you will need a free Ask an Expert account in order to post questions.