Life Science Curriculum 8-12

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Submitted by: Alexandra Trejo

Position: N/A

Institution: Azusa Pacific University

Title of Experiment: Monosaccharides Play an Important Role in Alcoholic Fermentation

Materials Needed:

- 4 Gatorade containers - substrates
- distilled water - glucose, fructose, sucrose+maltose
- 4 balloons - beaker
- 0.5 grams of yeast - thermometer, heat plate
- electronic weight scale - tissue paper

Scientific Background of Experiment:

This experiment will measure carbon dioxide as a waste product from yeast, which is given off during alcoholic fermentation. Monosaccharides, glucose and fructose, are utilized as substrates, as well as disaccharides sucrose (glucose and fructose) plus maltose (two glucose molecules). These substrates will be added to yeast to determine which gives off the most carbon dioxide gas. The process of alcoholic fermentation in yeast begins with the process of glycolysis.

Glycolysis is an anaerobic process by which living cells can obtain energy through the breakdown of simple sugars. In the absence of oxygen, the following process may be the forming of lactic acid in animals, or alcoholic fermentation in bacteria and yeast. The yielding products in alcoholic fermentation are ethyl alcohol and carbon dioxide. (Morton, 1980) Yeast is mainly utilized for carrying out alcoholic fermentation.

In 1876 Louis Pasteur discovered yeast to be living cells. In 1897, Buchner took the discovery a step further and found that yeast has the ability to ferment glucose to ethanol and carbon dioxide. (Jackson, 1981) Yeast are found to belong to a group of organisms known as fungi. They are known to reproduce quite rapidly by fission, or otherwise known as budding. Their cell wall swells at a region, and becomes a bud. The bud breaks off from the rest of the cell and becomes an independent cell. Yeast do not contain chlorophyll, so therefore cannot produce its own food. They feed on sugar from a variety of sources. (World Book Inc., 1994) Yeast is used by the wine and beer industry to ferment carbohydrates in their food to alcohol. Yeast is able to take in solutes across their cell membrane by diffusion, facilitated diffusion, and active transport. Simple sugars, such as glucose and fructose, are taken up by facilitated diffusion. (Unknown, 1981) Yeast may also metabolize their sugar in the presence of oxygen, but are unable to produce ethyl alcohol. Instead, the sugars are broken down into carbon dioxide and water. Only under anaerobic conditions, such as alcoholic fermentation, is yeast able to produce ethanol and carbon dioxide. (Davidson, 1999)

Glycolysis is the initial process in alcoholic fermentation, and requires the input of two ATP molecules. Glycolysis is a ten-step process, which requires the presence of ten enzymes that catalyze these reactions. The end product in this process is two molecules of pyruvate. It also produces four molecules of ATP, and two molecules of NADH. Since it takes two molecules of ATP to start the process, glycolysis only has a net yield of two ATP molecules. (Gauthier, 1996)

In the absence of oxygen, yeast now is able to undergo the process of alcoholic fermentation with the product of glycolysis, pyruvate, which becomes rearranged. NADH "gives electrons to acetaldehyde" and "when it receives the electrons it becomes ethanol". It utilizes glucose, fructose and other simple sugars as substrates, primarily producing carbon dioxide and ethanol. This process takes place in the cytoplasm of the cell. (Gauthier, 1996)


1. Blow up balloons, stretch before using.
2. Fill Gatorade containers up to 1 centimeter from the top with very warm water.
3. Add a single packet of yeast to each of the four containers. Mix well.
4. Measure each of the substrate amounts then add to their corresponding containers. Mix well.
5. Replace cap on all four of the containers.
6. Make sure the spout is "closed".
7. Attach balloons to each container with the spout still closed.
8. Once balloons have been attached, pull the spout of each container to the "open" position simultaneously.
9. Every15 minutes make observations and gently swirl containers. Do this for onehour.

Misc. Helpful Information/ Hints/ Suggestions:

Be sure each of the Gatorade containers are equal in size. Just follow the procedure methods and the experiment will turn out as expected.


Literature Cited (in order of appearance)

1. Jean Sloat Morton, Ph. D., Glycolysis and Alcoholic Fermentation,, 1980

2. Jackson: Cornell university, Alcoholic Fermentation,, 1981

3. World Book Inc., World Book Encyclopedia, Second Edition, 1994

4. Unknown author, Cornell University, Stuck Fermentations,, 1981

5. T. A. Davidson, Fermentation,, 1999

6. David Gauthier, DIY CO2- yeast,, 1996