EXPERIMENT 8 Alcoholic Fermentation, Lab Reports of Chemistry

Download EXPERIMENT 8 Alcoholic Fermentation and more Lab Reports Chemistry in PDF only on Docsity! Chem 115 D. Stiglich ​EXPERIMENT 8 Alcoholic Fermentation Materials and Equipment: ​Digital balance (0.01g precision); 4 x Pyrex® Screw-Cap Bacteriological Culture Tubes, 16 x 125 mm; 15 mL, Graduated Cylinder, Polypropylene, 10 mL; Nesting Graduated Beakers Set; Graduated Cylinder Polypropylene, 10 mL; Plastic cup to hold test tubes; 1 tsp. Fresh Baker’s yeast- fast-rising highly active; 1/8 tsp. measuring spoon; Water balloons that will fit on the test tubes; Metric ruler; Sugar. Introduction ​Alcoholic Fermentation in Yeast Adapted from “Alcoholic Fermentation in Yeast Investigation” in the School District of Philadelphia Biology Core Curriculum © 2011 by Drs. Jennifer Doherty and Ingrid Waldron, University of Pennsylvania Biology Department[1] All living cells, including the cells in your body and the cells in yeast, need energy for cellular processes such as pumping molecules into or out of the cell or synthesizing needed molecules. ​ATP ​is a special molecule which provides energy in a form that cells can use for cellular processes. Each cell in our body and each yeast cell can use the energy stored in organic molecules in food to make ATP. When O​2​ is available​, cells use ​aerobic​ ​cellular respiration ​to transfer energy from the organic molecules in food to ATP. As shown in the figure, aerobic cellular respiration is a complex process that begins with ​glycolysis​, followed by the ​Krebs cycle​ and the ​electron transport chain​. Aerobic cellular respiration can make up to 29 molecules of ATP per molecule of glucose. Most of this ATP is produced by the electron transport chain which can only function if O​2​ is available. (Figure revised from Johnson and Raven, 2004, ​Biology​, Holt Rinehart and Winston, p. 110) When O​2​ is not available​, cells can make ATP using glycolysis followed by ​fermentation​. Glycolysis produces 2 ATP and fermentation restores molecules needed for glycolysis to continue. Glycolysis followed by fermentation produces much less ATP than aerobic cellular respiration, but fermentation is very useful when O​2​ is not available. In the figure, fermentation is referred to as ​anaerobic​ processes. The "an" in front of aerobic means "not aerobic". There are two types of anaerobic fermentation: ● lactate​ ​fermentation​ (e.g. in muscles when an animal exercises hard) ● alcoholic fermentation​ (e.g. in yeast, which can be used to make wine or beer) ​★ ​Use the terms carbon dioxide and oxygen to complete the following equation to describe aerobic respiration. Glucose + ​_____​oxygen​________ à _______​carbon dioxide​________ + Water Pre-lab Questions- 1. Humans use ​yeast ​every day to make bread, wine and beer. What is yeast? It is a greyish yellow substance which obtains mostly from fermented beer, also used as a fermenting agent to help bread dough raise. If you want to make your own bread, you can buy yeast in the grocery store. This yeast consists of little brown grains. The little brown grains of yeast may not seem to be alive, but if you put them in water with sugar, the yeast will take up the sugar and use the energy stored in the sugar molecules to make ATP and carry out the processes of life. 5) Measure the depth of bubbles produced and observe the balloons as soon as the test tubes are prepared and after 10 minutes and 20 minutes. 7. Record your observations in these data tables. Sucrose Concentration Depth of CO​2​ bubbles at​: 0 minutes 10 minutes 20 minutes 0% (plain water) 10 20 30 1% sucrose 5 10 15 5% sucrose 2.5 5 10 10% sucrose 15 15 15 Sucrose Concentration Balloon Description 0 minutes 10 minutes 20 minutes 0% (plain water) 20 10 7.5 1% sucrose 15 7.5 3 5% sucrose 10 5 2 10% sucrose 7 7 7 Report Sheet- Submit only this page 1. Use the information from page 1 to complete the figures below. Fill in the ovals with the appropriate molecule. On the blank lines write the name of the appropriate process. In the boxes at the bottom of the figure write how much ATP is made in each pathway. 2. What is the main advantage of aerobic respiration? A major advantage of aerobic respiration is the amount of energy it releases. Without oxygen, organisms can just split glucose into two molecules of pyruvate. This releases only enough energy to make two ATP molecules. With oxygen, organisms can break down glucose all the way to carbon dioxide. 3. What is the main advantage of anaerobic fermentation? It regenerates NAD+ so that glycolysis can continue. 4. Compare your above results with your predictions. Did the amounts of CO​2​ produced at different sucrose concentrations match your predictions? If not, how did the results differ from your expectations? At some point they never matched. This may have occurred due to errors in the experiment such as temperature from surrounding and leakage of gases during the experiment. What conclusions concerning the relationship between sucrose concentration and the rate of alcoholic fermentation are supported by your results? The higher the rates of sucrose, the higher the rates of carbon dioxide is produced. [1]​ ​Teachers are encouraged to copy this student handout for classroom use. A Word file (which can be used to prepare a modified version if desired), ​Teacher Preparation Notes, comments, and other hands-on activities are available at​ ​http://serendip.brynmawr.edu/sci_edu/waldron/​. Additional biology activities are available at​ ​http://serendip.brynmawr.edu/exchange/bioactivities