Study on Anaerobic Respiration Rate in Fermentation with Various Drinks and Yeast, Study notes of Mechatronics

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Anaerobic Respiration (Fermentation)

by

Farah Masood

1. Introduction

Have you noticed that sometimes when you are running a race, you tend to run out of

breath and cramp up after a while? How will this affect your performance? When you have

trouble breathing it means that not enough oxygen is being delivered to your cells. Aerobic

respiration can only take place when there is oxygen present; therefore your body is not

producing enough usable energy, adenosine triphosphate (ATP), for your muscles to use as you

compete in the race.

How do you feel the day after the race? Most likely, your legs will be very sore. This

happens because in the absence of oxygen, the muscles switch to fermentation in order to

produce energy, and the final product of fermentation in the body is lactic acid. The build up of

lactic acid in the muscles cause the pH level of the body to become more acidic, the muscles to

get tired, and cramps to develop.

In this lab we will be studying anaerobic respiration, or fermentation, which is the

process of breaking down sugar to produce energy in the absence of oxygen. You will be using

yeast as the living organism (enzyme) that breaks down the different sugars to produce energy,

with alcohol as the byproduct of fermentation instead of lactic acid.

2. Background

Cellular Respiration:

Living organisms require energy to function. There is potential energy in the chemical

bonds of all organic molecules such as sugars, and some of the common sugars are: glucose,

sucrose, fructose, and lactose. However, this energy can not be used directly by the cells and so

these bonds need to be broken to release the energy in a form that is useful to the cells. Cellular

respiration is the process where energy that is stored in organic compounds is eventually

converted to a usable form called ATP (adenosine triphosphate). ATP is like money of the body,

cells in different muscles use ATP in order to do their work.

The two phases of cellular respiration is anaerobic and aerobic respiration. Anaerobic

respiration is phase 1 and it takes place in the cytoplasm. At the end of anaerobic respiration 2

molecules of ATP are produced. If there is oxygen, present then aerobic respiration or phase

2 can take place. If there is no oxygen present then phase 2 of cellular respiration cannot take

place.

Fermentation begins by splitting a glucose molecule into 2 molecules with 3 carbon

atoms each. This glucose splitting process is called glycolysis, during which ten individual

2

O

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chemical reactions occur, with each reaction controlled by a different enzyme. The end result of

anaerobic respiration, or fermentation, is 2 ATP and an alcohol, or an acid. Anaerobic

respiration can be summarized with the following chemical equation:

Energy + Glucose Ethanol + Carbon Dioxide + Energy

Yeast is used as the enzyme because it contains the enzymes that are needed for fermentation.

Structural Formula of Sugar Molecules:

Figure 1

Glucose is the most fundamental

molecular composition of all the sugars; its

structural formula is shown in Figure 1. That

means that the chemical bonds between its

elements are the easiest to break compared to

the bonds in a fructose molecule. Galactose is

another monosaccharide, or a single sugar, that

has very weak chemical bonds. Galactose is

an isomer of glucose, thus it is obtained by

reorienting the location of one of the hydroxyl

groups, , of the glucose as shown above in

Figure 1.

The “glucosidic” links in the

disaccharides, or double sugars, are more

difficult to break down than the interior bonds

of the monosaccharides. The “glucosidic” link

is the oxygen bond between the two sugar

molecules, as shown to the left in Figure 2.

ATP CH O CHCHOH CO ATP

Enzymes

6 12 6 3 2 2

+ ¾¾ ¾¾® + +

¾¾ ¾ ®

Yeast

OH

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Figure 2

3. Objective - Determine the rate of fermentation while using yeast as an enzyme to breakdown different

sugars.

• Learn how the type of sugar involved affects the rate of fermentation. 4. Equipment

Computer

Vernier computer interface

Logger Pro Software

Vernier Gas Pressure Sensor

Single-holed rubber stopper

Plastic tubing with Luer-lock fitting

Gatorade

Coke with completely released

100% fruit juice

Milk

600 ml beaker (for water bath)

Hot and cold water

Thermometer

Two 18 x 150 mm test tube

10 mL graduated cylinder

Utility clamp

Ring-stand

Yeast suspension

5. Experimental Procedure 1. Incubate the yeast solution in a 37 – 40 water bath to ensure that the yeast will remain

in a constant and controlled temperature. To prepare the water bath, pour warm and cold

water into the 600 mL beaker until the water temperature reaches 37 – 40. The beaker

should be filled with about 300 – 400 mL water, and leave the thermometer in the water

bath for the duration of the experiment to monitor the temperature of the water bath.

2. While the yeast in incubating, connect the Gas Pressure Sensor to Channel 1 of the Vernier

computer interface. Prepare the computer for data collection by opening the file

“Anaerobic Respiration” from the Living Environment folder.

3. Connect the plastic tubing to the valve on the Gas Pressure Sensor
4. Label the two test tubes 1 and 2
5. Your group will test two of the four drinks, as directed by your instructor. Using the

graduated cylinder:

• Pour 2.5 mL of the first solution into the test tube labeled 1
• Pour 2.5 mL of the second solution into the test tube labeled 2

Record which solutions you tested in Table 1.

6. Lightly stir the yeast suspension to mix the yeast that settled to the bottom. Using the

graduated cylinder pour 2.5 mL of the yeast suspension into the test tube labeled 1. Gently

mix the yeast and sugar solution.

2

CO

° C

° C

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7. Insert the single-holed rubber stopper into the test tube. Firmly twist the stopper for an

airtight fit and then secure the test tube with a utility clamp to the ring-stand. Then connect

the free end of the plastic tubing to the connector in the rubber stopper, shown in Figure 3.

Figure 3 (Masterman, 2003)

8. Then incubate the test tube for 10 minutes in the water bath. Make sure to keep the water

bath at a constant temperature (37- 40

0

C) and the test tube completely covered by the water.

Periodically check to ensure that the temperature remains constant. If the temperature falls

below or above acceptable levels, add cold or hot water accordingly. (If water is being

added to the bath, first remove the same amount of water that will be added to the beaker to

prevent overflow.)

9. After 10 minutes have elapsed you can begin measuring the gas pressure by clicking on the

Collect Data button,. Disconnect the plastic tubing from the Gas Pressure Sensor if

the pressure exceeds 130 kPa, because the pressure inside the test tube is too great. The file

is set up to collect data for 8 minutes.

10. After data collection has finished, remove the rubber stopper from the test tube and discard

the contents in a waste basket.

11. Determine the rate of fermentation:
    • First change the name of the Header in the Data Collection Window on the left to

the drink that is being tested (Gatorade, Coke, Juice, or Milk). This can be done by

double clicking the cell and then typing in the title into the little window that opens.

• To highlight the data move the mouse pointer to the point where the data values

begin to increase. The data should start increasing around 60 seconds. Drag the

pointer to the end of the data and release the mouse button.

• To obtain the rate of fermentation a best fit line needs to be drawn for the data.

After the data has been highlighted, click on the Linear Fit button,. A floating

box will appear with the formula for a best fit line.

• Record the slope of the line, , as the rate of respiration in Table 1. m

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• Close the linear regression floating box and move your data to a stored run. To do

this, choose Store Latest Run from the Experiment menu.

12. Use a notebook or notepad to fan air across the opening of the Gas Pressure Sensor.
13. Repeat Steps 6– 12 for the second sample.
14. Save all your data by choosing “save as” from the file menu, and save the file as Anaerobic

Respiration (Group #).

15. Share your data with the class by recording the fermentation rates you obtained for the two

drinks in the appropriate spot on the board.

16. After all the groups have recorded their data on the board, copy down all the values into

Table 2.

6. Results

Table 1: Group Data

Drink Tested Actual Temperature

(

o

C)

Rate of

Fermentation

(kPa/s)

Gatorade

Coke

Fruit Juice

Milk

Table 2: Class Data

Drink Tested Group 1 – Rate

of Fermentation

(kPa/s)

Group 2 – Rate

of Fermentation

(kPa/s)

Group 3 – Rate

of Fermentation

(kPa/s)

Group 4– Rate of

Fermentation

(kPa/s)

Gatorade

Coke

Fruit Juice

Milk

7. Analysis 1. Calculate the average rate of fermentation for each of the five drinks that were tested.

Record the class averages for the fermentation rates in Table 3.

Table 3: Class Average

Drink Tested Rate of

Fermentation

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(kPa/min)

Gatorade

Coke

Fruit Juice

Milk

2. Make a bar graph, using the graph space provided below, of the rate of fermentation vs.

type of drink. Use the fermentation rates calculated in Table 3. The rate values should be

plotted on the y-axis, and the type of drink on the x-axis.

3. Looking at the bar graph, can yeast utilize all the sugars equally? Explain.

Gatorade Coke Juice Milk

Type of Drink

Rate of

Fermentation (kPa/s

)

Bar Graph of Rate of Fermentation

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4. Explain why some of the sugars in the drinks were metabolized and the other sugars were

not metabolized as much.

5. Why do you need to incubate the yeast at 37- 40

o

C before you start collecting the data?

6. Why does all the from the coke need to be released before the yeast is added?
7. Explain some possible sources of error?

Reference

Chang, Raymond, Essential Chemistry: A Core Text for General Chemistry 2

nd

edition, 2000,

McGraw-Hill Higher Education, New York, New York

Hallman, Rick, The Living Environment: Biology, 2000, AMSCO School Publications, Inc.,

New York, New York

2

CO

R evitalizing A chievement by using I nstrumentation in S cience E ducation 2004 - 2007

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Johnson, George P., Raven, Peter H., Biology Principles & Explorations, 2001, Holt,

Rinehart and Winston, Austin, Texas

Masterman, David, Holman, Scott, Biology with Computers: Biology Experiments Using

Vernier Sensors 3

rd

edition, 2003, Vernier Software & Technology, Beaverton, Oregon

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Anaerobic Respiration (Fermentation)

Teacher Information

1. To Prepare Yeast Suspension: Dissolve 7 g of dried yeast for every 100 mL of water.

Incubate the suspension in 37 - 40 water for at least 10 minutes; then transfer the

yeast to dispensing tubes. Each group will need at least 5 mL of yeast.

2. Make sure that all the from the coke has been released.

° C

2

CO