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SEPGuides: Science Education Partnership: PreCut DNA Lab

SEPGuides is the go-to place for all SEP kit protocols and activities, as well as the posting area for announcements and program updates. If something is missing or you have an idea to contribute, please e-mail us at

DNA 1 - Precut

In DNA Lab 1, students become proficient in using gel electrophoresis while connecting concepts about DNA, enzymes, and charge. In this lab, students will run gel electrophoresis on precut lambda DNA and observe the differing banding patterns. Using a ladder, they can determine the approximate size of each fragment.

DNA Lab 1 Resources

Editable Versions

Additional Materials

Laminated Protocol Cards

Enzyme Restriction Resources

Enzyme Restriction Extras

NEB's video on Type II Restriction Enzymes

How to Pack a Gel Crate Like a Pro!

Yes, Gel Kit crates can be a pain in the . . . But! There's hope. Here are three guides, one for each crate. If items just aren't behaving, it's better to put them in a separate container (box, grocery bag) and bring them in that way. We would rather have them returned separate and intact, rather than together, smooshed and broken.

Save Time in the Lab

A significant reduction in gel electrophoresis running time can be achieved by decreasing the concentration of the running buffer (TAE) and increasing the voltage:

  • Decrease the running buffer from 1X to 0.25X
  • Increase the voltage from 100V to 200V
  • Reduce your running time from 45 minutes to 20 minutes.


  • Make the agarose with 1X TAE NOT the 0.25X running buffer
  • Do NOT run the gel longer than 20 minutes.

If you exceed 20 minutes the gel will melt.

Under these conditions, the top edge of the gel (where the wells are located) may begin to melt a bit, but this should not impact the visualization of DNA fragments.

- Tip courtesy of Essy Levy of Bio-Rad

Extra Resources

Here is a very cool time lapse video of gel electrophoresis in action, courtesy of retired SEP teacher and current RV explorer extraordinaire Aram Langhans.

Aram used the FlashGel System, created by Cambrex, and the actual running time was only 5 minutes. More info