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Genetic Scenarios and Toothpickase

Betty Ann Wonderly


My favorite teaching unit is a modification of a teaching unit published by GENESYStems and funded in part by the Foundation for Blood Research. The unit was written by Edward Kloza and Paula Haddow. The unit is a series of soap opera type scenarios that present various genetic defects as they are discovered in a make believe family. As each defect is discovered it is discussed and the pertinent information about that defect is given. The original unit comes with a series of written scenarios, fact sheet on the various disorders, and overheads to help present the information.


The first year I used the unit I used the prepared materials. However, by the second year the characters seemed to have developed a life of their own. They had moved to Texas, gone to UT and developed a whole new set of disorders and problems. I made new overheads and fact sheets to accompany the new disorders.

I also made slides of family and friends to represent the imaginary family. As I moved into my next unit on the human genome I found they kept cropping up. One member was involved in a paternity suit and DNA fingerprinting was used in his trial. It seemed that no matter what we were discussing it could be tied into this family in some way. I was using the BSCS Human Genome Lessons and I modified these by tying them into the family and using newspaper and magazines to show the relevance of the topics discussed.

We used the family in discussing the ethical issues involved in genetic testing. In both of these units we did the standard genetics labs such as analysis of human pedigrees and genetic corn. We also worked the standard genetics problems. This year I plan to let the students play the roles of the genetics counselors. They will have access to "A Handbook of Genetic Disorders" which will be compiled from the fact sheets and my research.

I have found that most genetic texts are too complicated for my students. Instead of presenting the story, I will give each group a brief outline and each group will present a different part of the story and provide information and counseling to the family.

The students learn the basics of human genetics, how to analyze genetic information, how to make predictions through working genetics problems, and ethical implications involved in genetic testing. They become aware of the research and information explosion in this field. The most important thing is they develop an interest and awareness of genetics and its effect on their lives.

Evaluation consisted of their performance on tests and quizzes, solving the genetics problems, analyzing their lab results, and participation in class discussion. The grades on this unit averaged 10 to 20 points higher than on other units. The percentage of students not paying attention in class dropped to 0. These results held true for all classes and were true both years the lessons were used.


Another lesson I particularly enjoy using is deals with enzymes. It was developed by Peggy Skinner of the Bush School in Seattle. She is a very creative and innovative person and has been a source of ideas and inspiration for me. It has worked extremely well for both my advanced and my beginning students.

In this activity the students are divided into groups of two. One student is the enzyme, toothpickase, which breaks toothpicks into two equal parts. You instruct them about active sites and combining with their substrate toothpicks. Also inform them that enzymes are blind so they must keep their eyes closed. The student partner counts how many toothpicks the enzyme breaks in 10 second intervals. This number should be cumulative eg; 1-10 for the first ten seconds 11-16 for second interval etc.

  • Place about 25 toothpicks in a fingerbowl.
  • The "enzyme" breaks these toothpicks and drops the products back into the bowl.
  • The teacher calls the time at 10 second intervals and each group records the number of toothpicks broken.
  • Graph results
  • The question arises as to what happens when you run out of toothpicks. This shows students what happens to the rate of the reaction as it progresses. You can also have the students wear mittens or gloves to show allosteric inhibition or add dissecting pins to show competitive inhibition. This is a most effective way of teaching enzyme activity. Hope you can use it.

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