MI: 3.2.2 Skin Cancer part II April 15, 2019 Types of Skin Cancer… Please take handouts. Get your journal out.

3.2.2 Skin Cancer Prevention Part 2 Part II: Mutant Yeast Ultraviolet light causes mutations in our DNA which can cause a cell to become cancerous or to die. Luckily, our cells have special enzymes that repair the DNA damage caused by ultraviolet light. However, occasionally the repair enzymes make a mistake which results in a mutation. The more exposure to UV light that one has, the more times the enzymes have to repair the DNA, which increases the chances that a DNA mutation will occur. One of the simplest ways to reduce your risk for developing skin cancer is to protect your skin from harmful UV rays with sunscreen. Sunscreen works by filtering or blocking dangerous UV rays from the sun which prevents the UV rays from damaging the DNA found in the skin cells. Yeast cells can be used as a “model system” to study the effects of UV exposure. Yeast cells are a good model system because they are single-celled organisms that are easy to grow. Since they are eukaryotes, their DNA is organized and replicated in much the same way as mammalian DNA. The enzymes yeast cells use to repair their DNA are similar to the enzymes used in mammalian cells. Scientists have been able to develop a UV-sensitive yeast strain whose DNA has been altered so that it is not able to repair its DNA. Observing how sensitive these mutated yeast cells are to UV exposure, we can learn more about the damage our cells must repair in response to our exposure to the sun. With a lab partner, you will determine how the two strains of yeast respond to exposure to the sun.

How is UV radiation damaging our DNA? How can DNA be repaired? Video clip UV Damage and Aging Video Clip DNA repair video clip UV Cancer and Aging video clip

3.2.2 Skin Cancer Prevention Part 2 Lab set up today! Read the directions. PPE is necessary-protect eyes and keep it sterile with gloves. Wipe down table before lab with Lysol wipes. After set up, work on Part III with your table team. Think about how you want to set up your investigation.

Skin Cancer Prevention Investigation Question: What is the effectiveness of sun screens and/or fabric against UV rays? Decide what variable you wish to use (fabric or sunscreen). You can also bring in items if you wish. Set up your experimental design with your team. Determine the following: Independent variable (the thing you are changing) Dependent variable (the thing you are observing—make it quantifiable) Control Trials You may use up to 5 plates for your investigation. Make your hypothesis. Set up as an If, then statement: If __________________, then __________________. Use the Lab Report Rubric as your guide. Independent variable Dependent variable

What’s next? Make sure you are finished with 3.2.1: Are you at Risk? We will grade next class. Start working on conclusion questions for 3.2.2: Skin Cancer You can answer #1-6 right now. Make sure to have a good handle on your experiment as you will be setting it up next class. Lab Report is a project grade (20% of total grade)