Yeast Respiration Fermentation Lab

Yeast Respiration/Fermentation Lab Cell Energy Unit Objective  To observe the process of cellular respiration in live yeast. We will also observe how changing food concentrations can affect the rate of cellular respiration. Background  Cellular respiration is the process of converting chemical energy (food) into ATP that the organism can use for its cellular processes. The equation for cellular respiration is below: C6H12O6 + 6 O2  6 H2O + 6 CO2 + ATP In this lab, we will observe yeast cells performing cellular respiration. Yeast are facultative anaerobes. This means that if oxygen is present, they will use cellular respiration. However, if there is no oxygen present in the environment, they will use alcohol fermentation instead. Both methods allow them to make ATP; however, respiration is much more efficient so given the choice that is the process they will carry out. In this lab, we will feed the yeast different food sources. In cellular respiration and in alcohol fermentation, carbon dioxide gas is given off as a product. We will trap the released CO2 in balloons and compare how much gas is produced for each of the beverages. By measuring the gas produced, we can determine how rapidly the yeast are carrying out their metabolic functions. More gas results in a larger balloon which means the beverage provided more energy for the yeast. --------------------------------------------------------------------------------------------------------------------------------------------PreLab  THIS SHOULD BE DONE BEFORE YOU COME TO CLASS! 1. Title and date of the lab (remember to include your lab partners names, write in pen, and add this lab to your table of contents) 2. Purpose  1-2 sentences describing the overall goal of the experiment; use complete sentences 3. Hypothesis  Write an if/then statement for this lab; hypothesize (which beverage) we will see the highest rate of respiration. LEAVE THIS BLANK until the day of the lab. You’ll create your hypothesis once you know what the beverages/energy sources are. 4. Lab Procedure (see below)  First list the materials needed for this lab. Next, write a procedure for the experiment. Use your own words to describe the steps in this lab. You should be able to do the experiment from what you write without using this lab sheet. You may do a numbered list here. 5. Variables  Sate the independent variable, dependent variable, and control for this experiment. 6. PreLab Questions  See Below; copy each question and ANSWER it BEFORE doing the lab OR answer in complete sentences. 7. Data  (see below) Copy the data table into your lab notebook. Give the data table an appropriate title. **ANOTHER OPTION FOR THIS LAB IS TO CUT OUT AND TAPE THE DATA TABLE INTO YOUR LAB NOTEBOOK** ---------------------------------------------------------------------------------------------------------------------------------------------Lab Procedures Materials  Erhlenmeyer flask Active dry yeast Beverages String Ruler Balloons Procedure  1. Make a hypothesis of which solution will produce the most energy. 2. Label the balloon with the ENERGY SOURCE (name and #) using a sharpie marker. 3. Fill each flask with appropriate ingredients – 1 tsp of yeast, 20 mL of the energy source AND 20 mL of warm water. 4. Mix thoroughly (by swirling) **NOTE: Make sure there is NO AIR in the balloon before placing it on top of the flask. Also make sure that the balloon is directly on top of the opening to the flask and is not blocked. Stretch the balloon a few times before using it** 5. Keeping the above in mind, place the balloon over the top of the flask 6. Wait until end of block, measure balloon at widest point with string, then measure the length of the string and record the circumference (in cm) in the data table. ----------------------------------------------------------------------------------------------------------------------------------------------------PreLab Questions  Copy these questions into your lab notebook and then answer them. You do NOT need to use complete sentences since you are copying the question. 1. Write the equation for cellular respiration. 2. What is the purpose of cellular respiration? 3. What are the two types of fermentation and what is produced in each? 4. What type of fermentation do yeast perform? 5. What is a facultative anaerobe? 6. HOW are we measuring the rate of cellular respiration in this lab? ----------------------------------------------------------------------------------------------------------------------------------------------------Data Tables  Either copy this data table into your lab notebook OR cut it out and tape it in. Flask # Energy Source 1 2 3 4 5 6 7 Water Circumference ----------------------------------------------------------------------------------------------------------------------------------------------------Post Lab Questions  Copy these questions into your lab notebook and answer them OR answer in complete questions. 1. What gas that is produced by the yeast? Why? 2. What process are the yeast doing? 3. Why must all the test tubes be set up in exactly the same way except for the differences in the beverage? 4. How do yeast break down food without oxygen (what process do they use)? 5. How do we know which beverage provides more energy for the yeast? 6. What is the yeast breaking down in this process? What is the yeast making in this process? 7. Which beverage provides the most energy? How do you know?