Students investigate an example of new traits arising in populations by watching a video that shows the growth of bacteria on increasingly high concentrations of antibiotics as the bacterial genome accumulates mutations that confer antibiotic resistance. Students wonder how these mutations can develop so quickly. Students create a mathematical representation of bacterial reproduction to model the speed at which these populations grow to figure out that while mutation rates make it seem like mutations are very rare, they are instead quite common due to the rate at which bacterial populations reproduce. They extend this to the rock pocket mouse model and see that in a case where organisms do not reproduce as quickly, the sheer size of an organism’s genome and the number of offspring produced in a generation still guarantee mutations will accumulate over time. Finally, students return to their consensus models and use them to make predictions about what would happen in the case of specific mutations in different environments. Then they test their predictions using a computer simulation and consider the affordances of one type of model over another.

This is Lesson 3 of the A Future Without Coffee Playlist.

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Student Materials

Per Student

• NIH EV PLAY 3.1 Transcript for Watch Antibiotic Resistance Evolve
• NIH EV PLAY 3.2 Bacterial Growth and Mutation Rates
• NIH EV PLAY 3.3 Transcript Natural Selection and the Rock Pocket Mouse
• NIH EV PLAY 3.4 Using Our Natural Selection Model to Make Predictions

Teacher Materials

• L3 Slides