Classroom Explorations: Model Organisms
Materials & Equipment
Group Size
  • whole class & individuals
Preparation
  • Preview the Web pages.
  • If you will be doing the activity with the entire class, print and duplicate the student page.
Alternative Approach
  • If you don’t have a tech center, you can project the Model Organisms pages for the class.
  • To research model organisms to find out why each organism is a good choice for a particular field of study.
This introduction to the concept of model organisms might be used after students have encountered a particular model organism; for example, Drosophila. You might discuss the following questions with the class:
  • How did the early genetic studies of the fruit fly contribute to our understanding of genetics in general?
  • What characteristics make the fruit fly a good model organism?
  • What are the limitations of using humans as research subjects?
  1. Provide the URL
    (www.exploratorium.edu/imaging_station/ students/ModelOrganisms_Student.doc)
    for the student page, and let students research the listed organisms.
  2. Lead a class discussion about some of the characteristics, both specific and general, that make the organisms they’ve learned about good model organisms. Point out or reinforce the idea that an organism that’s previously been studied is appealing to researchers because they benefit from what others have learned.
  3. Project the video of zebrafish development. Have students suggest reasons why the zebrafish is a commonly used model organism.
  4. Project the sea urchin videos. Ask students to suggest reasons why the sea urchin is a commonly used model organism.
Present the following scenarios to the class. For advanced students, you might ask for written responses. For less advanced students, you might have a class discussion and perhaps give them two organisms to choose between for each scenario.

Scenario A
A rare type of cancer appears to be genetic in origin. An experiment must be conducted to determine the potential pattern of inheritance of this disease. Which of the model organisms that you've learned about would you choose to use? Justify your choice.

Scenario B
A newly discovered plant from the tropics contains a molecule that appears similar in structure to a molecule found in abnormally low quantities in the brains of patients with Alzheimer's disease. Research is needed to determine if this molecule has potential in Alzheimer's therapy. Which model organism would you use? Why?

Model organisms are used to study broad principles of biology. Some general characteristics that make a species a good model organism include the following: easy and inexpensive to raise, short generations, lots of offspring, and a small number of genes. When an organism’s genome is sequenced, its value as a model increases. Prior knowledge about an organism based on earlier research is also an advantage.

Zebrafish
The zebrafish is a popular model organism because the embryo is clearly visible, so scientists can observe embryonic development. In addition, it grows from a single cell to a baby fish in only two days.

Sea urchin
The sea urchin is a useful model organism because fertilization is external and therefore visible. Embryonic development is visible as well.

Thanks to Alisa Poppen, biology teacher at Menlo School in Menlo Park, California, who developed a prototype of this activity.