Activity 1: Outbreak! Estimated time: 30 minutes

Two DoDDs Europe high schools are reporting cases of students infected with the ‘superbug’ called ‘methicillin-resistant Staphylococcus aureus,’ or‘MRSA’ [pronounced mer-sah] for short. At one school, four members of the football team were diagnosed and treated for MRSA infections. School officials are telling parents and students not to panic. Cleaning crews at both schools are sanitizing locker rooms and classrooms. Students are being told to pay better attention to hygiene. “They should wash their hands frequently, keep cuts and scrapes clean and covered with bandages, and not share water bottles or towels.” said Ms. Matteson, The school’s biology teacher.

Raise your hand if you ever Heard of MRSA Know anyone who has been affected by MRSA.

Real cases A couple of years back 6 high school football players from North Carolina had infections that looked like spider bites or large pimples. The infections grew larger and were identified as MRSA. All the students were eventually treated successfully with a class of antibiotics different from methicillin. The school started sanitizing lockers once a week and wrestling mats and gym towels every day. Similar cases occur across the country. Another MRSA outbreak that was in the news recently involved eight players on the St. Louis Rams professional football team.

October 2013: Austin Texas Bethany Burke age 15 picked up a MRSA infection Georgia Buccaneers had 2 players infected and the locker room was the suspected source.

Read Master 1.1, Identify any unfamiliar vocabulary. Work independently to answer the questions at the end of Master 1.1. Not graded as right or wrong…

Share ideas that you wrote down with class You should recognize that your classmates may have different ideas

T/F Bacterial population purposefully changed or changed simply because it “needed to” or “wanted to.” False

Researchers developed the antibiotic methicillin to treat people with infections of S. aureus that are resistant to penicillin. Within two years, populations of S. aureus that were resistant to methicillin started showing up in hospitals. How would a scientist explain how the change may have occurred in S. aureus populations?

A complete explanation of the evolution of resistance in S. aureus populations includes five major principles: 1) Variation: Within a population of S. aureus, some individuals are resistant to methicillin and some are not. 2) Inheritance: Resistance to methicillin in S. aureus has a genetic basis and is passed from parent to offspring.

Origin of variation: Random mutations in the genetic information of S. aureus led to differences in traits among individuals in the population. Fitness: When exposed to methicillin, individual S. aureus that were resistant to methicillin left more offspring than those that were not resistant. Evolutionary change in populations: The frequency of the gene that causes resistance to methicillin increased in the S. aureus population over time.

Choose the correct answer(s) A. People who have the infection become resistant to antibiotics. B. Bacteria population become resistant to antibiotics. C. Resistant bacteria are passed from person to person D. All of the above E. Only B and C are correct

What are the tenants of Natural Selection.

What is a mutation Brainstorm with the person next to you. Look up the correct answer. Mutations are changes in DNA. Mutations provide the variation that is seen in populations.

From the previous activity. Describe what you learned about mutations and disease from the MRSA case. Consider how mutations in people might affect health.

The goal for the following is for students to express ideas about how scientists can use their knowledge of evolution to inform medical research.

Aniridia: An Eye Disease. Will a volunteer to read the information aloud to the class. Take a few minutes to discuss the questions with a partner before participating in a class discussion.

Do you think the parents’ concern for their baby’s health is justified? Why? Most expectant parents are concerned about the baby’s health. These parents are understandably more anxious than normal because of the family history of aniridia (baby’s father and grandmother).

From the information provided, would you expect aniridia to be caused by an infection, an environmental factor, or a genetic factor? Explain your answer. The family history is a clue that aniridia has a genetic basis. Aniridia is a genetic disease.

Scientists have identified and isolated the gene that is mutated in aniridia. The gene is called “Pax6” and is important for the development of eyes in an embryo. Pax6 plays an important role in the development of the brain and pancreas as well as the eyes. However, for the purpose of this activity, students will focus on the gene’s role in eye development.

We will now examine data about aniridia and consider how an understanding of evolution can inform medicine. Each student gets one copy of Master 1.3, Learning about Human Health from Other Organisms.Master 1.3 You will work in groups of three to four to analyze the information provided and respond to the questions. After part 1 go to next slide.

Students simply need to recognize that the sequences for the Pax6 protein are very similar among these organisms. Part 2: Look at photos next page.

Photographs of Normal Eyes and Eyes with Pax6 Mutations

The purpose of students making these observations is to look at evidence for gene function (not to learn the anatomy of the eye). The main thing that students should observe is that, for all these species, eye development is abnormal in Pax6 mutants.