In this lesson, students will be using the BLAST tool to compare mitochondrial DNA samples from unknown whale species to known sequences.

Prior to this activity, students should have learned about cellular structures and DNA structure and function. Mitochondrial DNA (mtDNA) may be a new concept for many students, since biology classes primarily focus their study of DNA on nuclear DNA. In order to help students understand the structure and function of mtDNA, there is a WebQuest about mitochondrial DNA that the students can complete in class or as a homework assignment.

The BLAST portion of the lesson also provides the flexibility to tailor the lesson to student interests by providing three different scenarios from which to pick. Scenario 1, which involves determining the source of whale bones found in whale graveyard, focuses on the history of whaling. Scenario 2, which involves determining if the meat found at a restaurant came from a whale, focuses on wildlife crime and forensics. Scenario 3, which involves determining which bones belong to the real whale from which the model of the blue whale in the ocean hall of the American Museum of Natural History was created, would be a great follow-up to a field trip to the museum.

During a class period, students will cut and paste mtDNA sequences into the BLAST tool on the NCBI website. Teachers will need to make a digital copy of the sequences available to their students, either through a shared file or though a class website. The tool will compare these sequences to known DNA sequences on file to determine the source of the mtDNA. Students can then use that information to solve the problem outlined in their scenario.



Beth Marass, Jayne Ricciardi

Additional Resources

Watch the following YouTube video on how to use BLAST before completing the activity in class to improve your understanding of the search tool.

Next Generation Science Standards

Crosscutting Concepts
  • Patterns
  • Systems and system models

Core Ideas

  • LS3.B: Variation of Traits
  • LS4.A: Evidence of Common Ancestry and Diversity
  • Analyzing and interpreting data
  • Engaging in arguments from evidence

Ocean Literacy Fundamental Concepts

  • 6.G: Everyone is responsible for caring for the ocean. The ocean sustains life on Earth and humans must live in ways that sustain the ocean. Individual and collective actions are needed to effectively manage ocean resources for all.