Skip to Main Content
It looks like you're using Internet Explorer 11 or older. This website works best with modern browsers such as the latest versions of Chrome, Firefox, Safari, and Edge. If you continue with this browser, you may see unexpected results.

SEPGuides: Science Education Partnership: Precut DNA - Forensics

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

Forensics Resources

Forensics FAQs

How are the forensic markers different from Marker I, II and III?

Caren prepares all the forensic markers at SEP, while Markers I, II and III are ordered. 


What type of DNA was used for the restriction digest?

Lambda DNA


  • Label microtubes!
  • Use the chart as a checklist so you don't forget to add all reagents
  • Start with the STE buffer, then add Sample Loading Buffer. Add your DNA samples last.
  • When in doubt, change tips!
  • Teachers may receive different forensic markers. Check the microtube label and forensic marker chart to see which you have.


Forensics Lab

The DNA forensics lab is a version of SEP's DNA Lab 1: Pre-cut DNA. The DNA in this lab has been cut using different restriction enzymes. These pre-cut lambda DNA samples will be used as "suspects". One sample will have double the amount to act as "suspect" and "evidence".

SEP Teachers: if you have multiple classes and want to have different culprits, you can request 2X of one of the Forensics Markers so you can have different culprits for different classes

Samples Provided:

  • DNA from suspect A (Marker I/EcoRI) (green tube)
  • DNA from suspect B (Marker II/Hind III) (pink tube)
  • DNA from suspect C (Marker III/EcoRI + HindIII) (blue tube)
  • DNA from suspect D (Forensic Marker 1) (purple tube)
  • DNA from suspect E (Forensic Marker 2) (purple tube)
  • DNA from suspect F (Forensic Marker 3) (purple tube)
  • Evidence DNA (tube with double the amount)
  • 1 kB Ladder (orange tube)

Possible Forensic Markers Chart

The chart above shows the banding patterns of the different pre-cut DNA samples SEP provides. The first three samples, Marker I, Marker II, and Marker III are the standard markers provided in DNA Lab 1. In this lab, we provide three extra forensic markers that has also been pre-cut. The labels on the tubes will tell you which samples you were given.

Forensics Reagent Chart