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Cut It Out!

Editing DNA with CRISPR-Cas9


Grace A. Farber
Department of Biological Sciences
University of the Sciences
Amy T. Hark
Biology Department
Muhlenberg College


This directed case study was developed to introduce students to the CRISPR-Cas9 system for genome editing. CRISPR-Cas9 has made numerous headlines in both the scientific and popular press, and thus serves as an excellent model for learning current biotechnology and applying concepts from biology courses. After providing a general overview of CRISPR-Cas9, the majority of the case focuses on the clinical applications of the system as experienced by a carrier for the X-linked recessive allele underlying Duchenne Muscular Dystrophy. The case is structured so that students use a variety of popular and scientific sources (some of which may require a subscription to access-check with your institution), increasing in difficulty as they move through each part of the case. The goals are for students to learn the molecular mechanisms of CRISPR-Cas9, the benefits and limitations of the system, and the clinical applications of the technology. Open-ended questions are included to spark discussion of ethical considerations, societal impacts, and the overall implications of the technology.


  • Describe the origin and function of CRISPR and Cas components used in genome editing.
  • Offer strengths and limitations of the CRISPR/Cas method compared to other DNA editing and gene therapy approaches.
  • Explain how CRISPR/Cas could be beneficial in basic research and used in clinical applications.
  • Discuss potential challenges in using CRISPR/Cas.
  • Explain how the CRISPR/Cas system may alter genomes differently if it works via non-homologous end-joining (NHEJ) or homology-directed repair (HDR).
  • Discuss ethical issues that are raised by the development and use of genome editing technology.
  • Describe the molecular interactions and functions that drive CRISPR/Cas.
  • Retrieve and use popular and scientific news pieces to increase understanding of research and technology.
  • Use scientific primary literature to increase understanding of research and technology.


CRISPR/Cas; genome editing; DNA repair; genetic inheritance; central dogma; Duchenne Muscular Dystrophy; gene therapy; RT-PCR

Topical Areas


Educational Level

High school, Undergraduate lower division, Undergraduate upper division



Type / Methods

Analysis (Issues), Directed, Journal Article



Subject Headings

Biotechnology  |   Genetics / Heredity  |   Molecular Biology  |  

Date Posted


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The following video(s) are recommended for use in association with this case study.

  • Jennifer Doudna: How CRISPR Lets Us Edit Our DNA
    This TED Talk, delivered by one of the co-inventors of CRISPR-Cas9, provides an overview of how the system works and a call to the scientific community to pause and discuss the ethical implications of this new technology. Running time: 15:53 min. Produced by TED, 2015.