Lesson Plan - NIH Office of Science Education
Lesson Plan - NIH Office of Science Education
Lesson Plan - NIH Office of Science Education
- No tags were found...
You also want an ePaper? Increase the reach of your titles
YUMPU automatically turns print PDFs into web optimized ePapers that Google loves.
Cell Biology and Cancertypes <strong>of</strong> adult cancer, provided additional support for the hypothesis<strong>of</strong> multistep carcinogenesis. In fact, one <strong>of</strong> the goals <strong>of</strong> research todayis to identify each <strong>of</strong> the steps and genes involved in the long and complex succession <strong>of</strong> events that occurs to create the malignant growth <strong>of</strong>cancer cells.Whereas Activity 2 illustrates the contributionthat cell biologists andgeneticists have made tounderstanding cancer,Activity 3 illustrates thecontribution that epidemiologists have made.One <strong>of</strong> the most excitingaspects <strong>of</strong> cancerresearch in recent yearshas been the construction <strong>of</strong> an understanding<strong>of</strong> cancer that unifies thework <strong>of</strong> many types <strong>of</strong>scientists studying cancer for more than 100years.Note that this question returns students to the challenge they weregiven in Step 4.17. Challenge your students to evaluate the models they used to test the differenthypotheses for the development <strong>of</strong> cancer (that is, to think aboutthe ways in which the random number table exercise and the CD-ROMbasedsimulation do and do not match reality).Remind students that all models are inaccurate in some respects. Forexample, the mutational events within cells may not be completely random, as the models assume. The models also assume that the probability <strong>of</strong> each individual mutational event is the same, and this may notbe the case. There is some evidence, for example, that some mutationsincrease the probability that other mutations will occur. In addition, themodels do not consider that some mutations may be detected andrepaired. Nevertheless, the fact that the models the students used arenot perfect does not mean they are not useful tools for understandinghow disease processes work.18. Close the activity by distributing one copy <strong>of</strong> Master 3.6, Testing anExplanation by Looking at Additional Data. Ask students to use theirunderstanding <strong>of</strong> cancer as a multistep process to explain each <strong>of</strong> theobservations listed.Question 1 Cancer is a disease <strong>of</strong> aging.The questions on Testingan Explanation are challenging, but they represent an excellent opportunity for you toevaluate your students’understanding <strong>of</strong> theactivity’s major conceptsand their ability to applytheir understanding tonovel situations.Students should be able to explain it takes time for all <strong>of</strong> the mutations involved in the development <strong>of</strong> cancer to accumulate, and thatthis explains why the incidence <strong>of</strong> cancer increases with age (that is,why cancer is more likely to “strike” in the middle or later years thanin childhood, youth, or young adulthood.Question 2 You’ve come a long way, baby.Students should be able to explain that as these women began tosmoke, they began to accumulate cancer-causing mutations in theirlung cells. Because the accumulation <strong>of</strong> these mutations to the pointwhere a cell becomes cancerous takes time, the results <strong>of</strong> theincrease in the number <strong>of</strong> women smoking (in the form <strong>of</strong> anincrease in lung cancer among women) did not begin to appear for20 to 25 years.Question 3 Genes and increased susceptibility.Students should recognize that if a person is born with a cancercausingmutation already present in his or her cells, he or she has62