Lab 6. Alcoholic Fermentation (Revised Fall 2009) Adapted from Experiment 12B in Biology with Computers Lab 6 -Biol 211 - Page 1 of 8 Lab 6. Alcoholic Fermentation in Yeast—an Independent Project Prelab Assignment Before coming to lab, read carefully the introduction and the procedures, below, and then complete the prelab questions at the end of this lab handout. Hand in the prelab assignment just before the start of your scheduled lab period. Goals of this Lab After completing this lab exercise you should be able to cooperate with group members to carry out the steps of the scientific method while carrying out an independent laboratory investigation:  Select a problem to study  Propose one or more testable hypotheses  Make predictions from the hypotheses  Design and perform experimental procedures to test the hypotheses  Analyze/interpret the results  Present your team’s research findings by making an oral presentation to the class. Introduction Over the next few weeks you will work collaboratively with your group to adapt the procedure used in Lab 5 to answer a scientific question concerning alcoholic fermentation by yeast. This investigation will allow you to be creative while getting practice applying the steps of the scientific method. This experience is designed to further your understanding and appreciation of the scientific process in a semi-structured situation similar to that used by researchers in their work. The success of your group depends entirely on the careful and conscientious effort of each person. The division of labor is the responsibility of the team. This dependence on others is also characteristic of research and many other aspects of life (as you may already know!!). Upon completion of the lab work your group will present before your peers in class an oral presentation of your findings, an activity done daily by scientists around the world. As mentioned above, the lab work required for this project will span over several weeks. The primary factors that will influence the amount of time spent in the lab include how well you design your lab experiment(s), your lab skills, and how efficiently and effectively you work as a group. Moreover, thorough preparation by all group members before performing experiments in lab will minimize the amount of time required in the lab. One two hour lab period will be provided for this experiment, the first hour of which should allow you to complete Lab 5, while the second half of the lab period will allow you to get started on Lab 6, your independent investigation. You are expected to utilize the biology lab outside of class time to complete the bulk of your project. The laboratory rooms are open Monday through Friday for activities involved in this lab—check with the Biology lab technician, Kathleen, the for the exact times the biology lab will be open.Lab 6. Alcoholic Fermentation (Revised Fall 2009) Lab 6 - Biol 211 - Page 2 of 8 Prelab Tasks 1. Before coming to lab complete the Prelab Questions on the last two pages of this handout. Use the information below as a guide: a. Select a question that you would like to investigate from the list below. If you have an idea for a question that is not listed below check it out with your instructor. Your instructor must approve the question your group selects. Things to consider when selecting a question to investigate: - You should understand the underlying concepts behind question selected. For example, if question #7 was selected, then you should have a thorough understanding of how and why changes in pH affect biological reactions. Or if question #8 was selected, you should have some knowledge about how and why ethanol affects cells and their plasma membrane. - You will need to consult your textbook, the introduction section of handout, and other resources to obtain supporting/background information about the question you select. b. Propose one or more testable hypotheses. c. Design an experiment using the materials available to test your hypothesis using the KISS! philosophy (Keep it simple stupid!). Consult with the Biology Lab Technician and/or your instructor concerning the availability of materials not listed in the materials section below. d. Be sure that all group members understand the techniques and procedures that you will use. e. Form a research team with two or three other students. The maximum group size is four. f. Assign tasks to be performed by each team member. Possible Questions to Investigate Background: At least three quarters of all women will experience a “yeast” infection at some point in their lives. A yeast infection is simply an imbalance of yeast in the vagina caused primarily by an overgrowth of the yeast fungus, Candida albicans. Candida live in small numbers and is always present in a woman's body (and in a man's too!). It's also the same fungus that causes diaper rash. Usually yeast is kept in check by “helpful" bacteria which are naturally present. Sometimes the normal balance of the vagina is disturbed. When that happens, Candida albicans can multiply, resulting in a vaginal yeast infection known as candidiasis. Yeast infections are the second most common cause of vaginal irritation, and can also occur on the male penis, particularly in uncircumcised men. Symptoms include severe itching, burning, and soreness, and irritation of the vagina and/or vulva, and a whitish or whitish-gray discharge that may have a "yeasty" smell like beer or baking bread—the odors of alcoholic fermentation! Anyone that experiences the symptoms of a yeast infection should consult their medical doctor A.S.A.P. That said, below are listed five “home remedies” used to treat yeast infections. Select one of the five home remedies and design an experiment to determine if it decreases the rate of alcoholic fermentation in baker’s yeast. If it does, then what is the minimum concentration required to stop alcoholic fermentation? Develop a quantitative relationship that will allow you to predict the rate of fermentation at varying concentrations of the home remedy. 1. Hydrogen peroxide. Hydrogen peroxide is produced naturally by acidophilus bacteria in the vagina, and kills yeast. One home remedy uses 1 teaspoon of 3% hydrogen peroxide from your market or pharmacy with 1 cup of water. 2. Garlic. Garlic is believed to contain natural antifungal substances that kill off yeast. 3.