Case of the Broken Beaker

case-of-the-broken-beaker

Case of the Broken Beaker is an activity developed by MdBio Foundation to help students explore the use of DNA profiling and gel electrophoresis. In this lab, students will use restriction enzymes and agarose gel electrophoresis to create a genetic profile.

DNA profiling is a technique frequently used for solving crimes and confirming if people are related to each other. It involves the testing of skin cells, hair roots, or a small amount of blood or saliva.

Restriction Enzymes are enzymes found in bacteria that cut DNA. The reason the DNA needs to be cut is so that you can sequence the small fragments via gel electrophoresis.

Gel Electrophoresis is a laboratory method used to separate mixtures of DNA, RNA, and protein according to their size. In gel electrophoresis, molecules are pushed through an electrical field with small pores, and separated based on their length. A molecules distance traveled is inversely related to it’s size, meaning the smaller the molecule, the greater distance it will travel.

Below are pre laboratory engagement and post laboratory extension activity suggestions that teachers may use in their classrooms as they see fit. Students who participate in the companion laboratory activity onboard MdBioLab will learn how to create a DNA profile in order to solve the Case of the Broken Beaker.

Learning Objectives

Upon completion of Case of the Broken Beaker Lab, students will be able to:

  • Explain how restriction enzymes are used to create unique genetic profiles
  • Explain how gel electrophoresis can be used as a tool to visualize DNA products
  • Create DNA profiles using the restriction enzyme HindIII and gel electrophoresis
  • Differentiate between different crime scene suspects based on their DNA
  • Analyze the validity of the DNA evidence

Background Information

Follow these links for more information:

Pre-Laboratory Engagement

Engage students in studying the relation between DNA profiling and Crime Scene investigation

Pre-Lab Questions
  • What are some methods used for DNA profiling?
  • What is DNA profiling used for?
  • How can gel electrophoresis help you match two DNA sequences?

Laboratory Activity

This morning, the MdBioLab instructors returned to the truck to find that someone had forced their way onboard the night before and stole over $20,000 worth of equipment but examination of the security footage could only confirm that a single person,  whose identity was concealed from the camera, carried out the heist.

Luckily for us here at MDBio Lab, several witnesses, who observed a person fleeing from the scene the previous night, provided officers with a fairly detailed description of the offender. Using these descriptions, officers have rounded up four suspects that have committed similar crimes and required they submit their DNA for analysis. The MdBioLab and police department need you to help create a DNA profile for each suspect that will assist the D.A. in prosecuting the case

Post-Laboratory Extension

For further knowledge of gel electrophoresis and DNA matching, visit: http://www.sumanasinc.com/webcontent/animations/content/paternitytesting.html

For further knowledge of restriction enzymes, visit: http://highered.mheducation.com/sites/dl/free/0072421975/196644/restriction_endonucleases.html

 

Specifications

  • Skill Level: Advanced
  • Focus: Genetics, forensics
  • Time: 70 – 90 minutes

Student Handout

NGSS Alignment

HS-LS1 From Molecules to Organisms: Structures and Processes

Key Words

DNA, electrophoresis, forensics, law enforcement, controls, UV, fragments, fingerprinting, profiling, crime scene investigation

Additional Resources

Dolan DNA Learning Center
Explore animations and other information on restriction endonucleases. Additional information on genetic engineering is also included if you’re feeling saucy!

New England Biolabs
Restriction endonuclease overview from the suppliers themselves

Quickgrabs

Gel Electrophoresis Tools
Run a virtual gel electrophoresis. This site also has many resources