Classroom Activities
Among the classroom activities to be incorporated in this unit are the following.
Molecular Genetics Sentence Construction - Students construct sentences comprising three letter words. The letters in the sentences are to represent individual DNA bases in the gene. The words are to represent triplet codons coding for amino acids. The sentence, as a whole, represents the protein. Most critically, the intended meaning of the sentence represents the function of protein. The individual letters of the sentences are to be transferred on to separate pieces of paper large enough to be easily manually manipulated (e.g. index cards). Students can simulate various mutations by adding, removing, or changing one or more letters to/from/in their sentences and assessing the extent to which the originally intended meaning of the sentences are affected. The extent to which the originally intended meaning of the sentence is distorted is a stand-in for how much of the function of a particular protein is changed after a mutagenic event. Students can work in pairs or small groups in which they exchange sentences, identify the types of mutations being represented and compare the effects of these mutations. Depending on the availability of technological resources in the classroom, the digital “Mutations” model developed by The Concord Consortium (https://concord.org/stem-resources/mutations) can also be incorporated in this activity. The “Mutations” model allows students to create and edit DNA sequences and observe the effects changes in DNA sequence on the peptide sequence as well as the interactions among the peptides themselves.
One possible assessment method for this learning activity also emphasizes the random nature of many mutagenic mutations. The instructor has two containers with slips of paper, one container with “mutation instructions” (e.g. “remove letter”, “add 3 letters”, “repeat letter four times”, etc.) and the other container with “location instructions” (e.g. 5th letter). Students chose at random one paper from each container, then must identify/describe the type of mutation resulting and assess the extent of the consequence on the gene’s function.
Students can also by assessed by creating a large size poster display that show the sentence construction framework and explicitly makes the connections to gene mutations (with examples).
Data Analysis and Conclusions – One of the emphases of this unit is analyzing and interpreting data, one of important NGSS Science & Engineering Practices. In this learning activity students are provided data sets, tables, graphs, etc. from published research journal articles. Students then are asked to examine the data and use a graphic organizer to make sense of the information presented. The graphic organizer is simple and contains three boxes, each with a set of sentences intended to guide the student’s exploration of the date.
Box 1 questions - Describe the data (what kind of information, how is it organized, where did it come from, etc.). Box 2 questions - What patterns/trends/correlations do you notice in these data? Which trends stand out the most? Do all the data fit these patterns (are there any outliers?)? Box 3 questions - What do the patterns/trends/correlations lead you to conclude? (what might the trends and patterns mean?)
In subsequent lessons and units, students will use the insights from data analysis done in this manner to construct scientific claims the supported by data and structured in a coherent way.
Letter to the Author/Editor – A goal of this unit, and indeed the course overall, is to develop students who are more critical consumers of scientific information. My students sometimes have a tendency to accept information presented to them without critical examination. I remind students that when assessing the reliability of information, it is important to consider how an author/speaker presents an argument, but it is also important to keep in mind that even well-organized data is sometimes flawed and eloquent speakers can be wrong. At the very least, scientists often disagree in whole or in part with information that is presented to them. In these cases, in is important to be able to assess the information presented to you and construct a coherent argument of your own.
The controversy regarding the recent FDA approval of Eteplirsen provides a useful example to emphasize this point. One of the important texts used in this unit is from the opinion section of the December 13, 2016 issue of the Journal of the American Medical Association (JAMA) – Volume 316, number 22. In the piece doctors Aaron S. Kesselheim and Jerry Avorn, make the case that the approval of Eteplirsen is problematic because of certain methodological and procedural issues (e.g. small sample size of the study group). In this learning activity students compare these doctors’ critiques with the data and arguments presented by the original researchers and then present their arguments as to the validity of the arguments of either party. Following this, students apply critical eyes to conclusions drawn from research data and write a “letter to the editor/author” in which the present critique the research and its conclusions. The emphasis here must be on the strengths and weakness of the research/data (“What was done well? What can be improved? What other questions should have been asked?, etc..) and crafting an evidence-based argument.
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