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Little Girl Lost: A Case Study on Defective Cellular Organelles


Tracie Y. Hudson
Department of Biology
Malcolm X College


This case study introduces students to the structure and function of cellular organelles and seeks to show their importance by discussing diseases and disorders that can result when an organelle does not function as it should. The storyline follows a family whose joy at bringing home a new baby is soon altered by their child's sudden illness, which is eventually diagnosed as Leigh Disease. This disease occurs when defective mitochondria fail to produce energy needed by the cell, particularly affecting cells with high-energy needs like those in the brain, muscle, and gastrointestinal tract. The narrative also discusses some of the ways in which Leigh disease is inherited, treatment options, and the typical prognosis. The case was designed for an introductory non-majors biology course, but could also be used in other science or health related courses. Instructors also have the option of running the case in a "flipped classroom" in which students watch three recommended videos outside of class as a way of preparing for working on the case in class.


  • Define the term organelle.
  • List the key organelles found in animal cells.
  • Describe the functions of animal cell organelles.
  • Map other disorders and syndromes to the appropriate defective organelles.
  • Describe Leigh Syndrome as well as other disorders and syndromes linked to defective cellular organelles.
  • Compare and contrast cellular structure and function to that of a factory.
  • Create analogies to aid in understanding and remembering the function of cellular organelles.


Organelles; cellular structure; inheritance; plant cells; animal cells; failure to thrive; Leigh Disease; mitochondria; mitochondrial disease; autosomal recessive mutation

Topical Areas


Educational Level

High school, Undergraduate lower division, General public & informal education



Type / Methods

Directed, Flipped, Interrupted



Subject Headings

Biology (General)  |   Cell Biology  |   Genetics / Heredity  |   Science (General)  |  

Date Posted


Teaching Notes

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Answer Key

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

  • Through the Virtual Cell
    This video provides an overview of many cellular organelles and also discusses transcription and translation. Running time: 6:47 min. Produced by NDSU Virtual Cell Animations Project, 2009.
  • Faces of Mitochondrial Disease—The Swinns
    Emily Swinn and her family discuss what life is like for Emily, who suffers from a mitochondrial disease. Running time: 2:58 min. Produced by the United Mitochondrial Disease Foundation. Uploaded to YouTube October 29, 2000.
  • Cellular Respiration and the Mighty Mitochondria
    This video provides a general overview of mitochondria, ATP, and cellular respiration. Running time: 7:48 min. Produced by the Amoeba Sisters, 2014.


Kristin M Donovan de Iturrino
Grapevine, Texas
Thank you for this case study. I use it in my Pre-AP Biology course and the students really enjoy the process of unfolding her diagnosis.