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Genetic Uniqueness: RFLP

Activity Description

Restriction fragment length polymorphisms were some of the earliest molecular markers used in forescic science. In this activity students solve a hypothecial crime using RFLPs. They are given 2D models of DNA sequences and have to use the RFLP variants to identify the criminal. 

Estimated Time of Activity

Up to 1.5 hours

Activity Objectives

Students will be able do the following as a result of the activity:

  1. Define RFLP
  2. Explain the difference between DNA sequence variation and DNA size variation. 

Activity Prerequisites


Activity Instructions

  1. Have students share what they know about gel electrophoresis
  2. Distribute electrophoresis handout and discuss fragment size separation
  3. Distribute RFLP handout and discuss the crime scenario
  4. Explain the GAATTC motif and have students "digest" their "fragments" where they find this motif
  5. Have students record their fragment profiles on the class board
  6. Discuss the class results and identify the criminal


Students should hand in their worksheets where they have correctly defined RFLP, worked out their RFLP fragment sizes, and correctly identified the criminal. 


  • RFLP handout
  • Electrophoresis handout
  • RFLP 2D sequence model

Instructor’s Notes