Determining Relationships in Families using Gel Electrophoresis

Overview & Concepts

A daughter thinks she’s adopted and wants to determine if her parents are her biological parents.  Students discover how gel electrophoresis is used to help the daughter determine if she is adopted or not.  In addition, students apply previously learned material (pedigree, Punnett square, etc.) to help understand the process and content. 

Grade Level: 

Concepts Covered: 

Genetics, gel electrophoresis, pedigree, patterns of inheritance

Prior Knowledge Required: 

The lesson requires knowledge of genetic inheritance, some general understanding of gel electrophoresis, and correct use of lab equipment associated with lab (i.e. micropipettes).

Activity Notes

Days to Teach: 

1.5 blocks (120 minutes)

Teaching Tips / Activity Overview: 

  1. Prep Lab: Teacher will discuss lab with students and review proper procedure.
  2. Electrophoresis Lab: Students take the 1st day to make the agarose, let the gel sit, load the gel, and allow the gel to start to run.  The staining the students will probably start, but the teacher will finish after school or throughout the day. 
  3. Analysis: Students look at their results and begin analysis, draw the gel in lab reports and begin answering questions.  Teacher monitors students’ progress and answers questions when needed. 
  4. Class Discussion: What did you learn?  How can this be applied to your life?  Why is gel electrophoresis so important? 
  • Instead of buffer, Gatorade can be used as an alternative since DNA is not being used.
  • Remind students, DNA “runs to red” (DNA is negatively charged so it moves toward the positive (red) electrical terminal). 
  • Do a test for the movement of the dyes before making solution to ensure the dyes move in the right direction (i.e. are negatively charged) and have different molecular weights (so they separate in the gel). 


Analysis questions and class discussion


  1. Discuss: How else could gel electrophoresis be used in the field?
  2. Complete gel electrophoresis using the students’ DNA for a specific trait (i.e. PTC taster).


  1. Pre-lab information or the process of gel electrophoresis can be found at
  2. Another good website the students can view before completing lab is to give students a better understanding of what happens during the procedure.


Procedure, teacher notes, and ideas adapted and taken from the Duchenne Muscular Dystrophy Medical Case Electrophoresis lab completed during F&M’s Bioinformatics Seminar 2012. The DMD example is adapted from an activity in Washington University’s book Modern Genetics 2003 (

Academic Standards
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