Evolution and cancer

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Revision as of 13:02, 9 April 2008

Evolution and Cancer

Lesson Overview Students read a brief passage that introduces the concept that the development of cancer is analogous to evolution. They learn about the characteristics of cancer cells by viewing the “Hallmarks of Cancer” section of the www.insidecancer.org site. For each hallmark of cancer, they write a brief summary statement explaining how that hallmark makes cancer cells more “fit” in the competition with normal cells. Students then do a class simulation that illustrates how multiple mutations lead to the evolution of normal cells into a population of malignant cancer cells.

Goals and Objectives

Students will: 1. explain the hallmarks that distinguish a normal cell from a cancer cell.

2. analyze and interpret the results of a simulation that illustrates the transformation of normal. cells into malignant and drug resistant cancer cells.

3. apply the concept of natural selection to understanding cancer evolution

Assumptions of Prior Knowledge Students should have a basic understanding of:

• evolution and natural selection.

• normal cell structure and function.

• mitosis and genetics (particularly characteristics of DNA and mutations which may occur) would be helpful.

Common Misconceptions

Students do not clearly understand that the progression from normal cells to cancer cells typically involves multiple mutations (“multiple hits”). Students may recognize that cancer involves uncontrolled cell division, but they rarely understand that cancer cells have other characteristics that affect their reproduction and survival. Students may think that in the future scientists will discover a single cause for all types of cancer.

Students may think that evolution only happened in the distant past. They may not realize that evolutionary biology has an impact on their future. Students may think that evolution only results in the production of new species.

The Lesson

Preparation Before class: (materials, handouts etc.)

• Photocopy one Cancer and Evolution student sheet for each student. (See Appendix A)

• Photocopy one Table 1. The Evolution of Cancer for each student (See Appendix B)

• Photocopy (laminate or put in sheet protectors) 15 sets of the Mutation Cards—A-K. Printing the backs of the card is optional. Shuffle the mutation cards. (See Appendix C)

• Photocopy 1 set of student signs (1-10). Laminate or put in sheet protectors. Attach string to the signs so that students can hang them around their necks. (See Appendix D)

During class

• Before starting the lesson, assess students’ prior knowledge by having them to answer the following questions:

o How are normal cells different from cancer cells?

o How are normal cells similar to cancer cells?

• Hand out the Evolution and Cancer student sheets. Read the three introductory paragraphs for Part 1 aloud.

• Ask students to go to http://www.insidecancer.org. Provide students with information about how to find “Hallmarks of Cancer” section of the site and how to navigate within this section.

• Allow at least 30 minutes for students to view the information in the “Hallmarks of Cancer” section. For each hallmark, they should explain how that hallmark makes cancer cells more “fit” for competing, surviving and reproducing in the body’s internal environment.

• Select 10 students to be participants in the simulation. Give each player a sign (1-10) and ask them to wear the signs. Ask these students to move to the front of the room.

• Read the first four paragraphs in Part 2, aloud, to the class.

• Read the instructions for the simulation, aloud, and have student participants follow the instructions. Note, student participants do not record data during the simulation. Participants can use data tables created by other students in the class to answer the questions at the end of the simulation. All students who are not participants should record the “data” as described in the instructions. (Optional: create a single class data table on a transparency).

• Hints for the simulation:

      o	Project a “class data table” and model how to record data for at least the first three generations.
      o	 Consider providing markers so that students can mark the letters that represent the hallmarks of cancer.  
      o	A sample of how to fill in the data table and tally the columns is provided in the teacher answer key.

• At the end of the simulation, ask students to complete the questions in Part 2.

• If time permits, revisit the lists students made describing the ways in which cancer cells are different from and similar to normal cells. They could add to these lists. Consider asking students what questions they have about cancer cells or evolution.