Yeast Lab6

Art R. Marina M. Sarah H.!
Mrs. Khaled!
October 12th 2014!

The Effect of Glucose on The Cellular Respiration of Yeast!
Purpose: !
The purpose of this lab is to determine if the quantity glucose solution will increase or decrease the rate at which cellular respiration occurs at within the tested 20% yeast suspension.!
Question:!
What are the effects of increasing or decreasing the quantity of 0.06mol/L glucose solution on the cellular respiration within the tested yeast molecules?!
Hypothesis: !
When the quantity of glucose solution is increased, the rate at which cellular respiration occurs within the yeast molecules will increase respectively. !
Material:!
-20 mL of 20% yeast suspension ! -20 mL of 0.06 mol/L Glucose solution -Test Tubes !
-0.005% methylene blue solution ! - Test tube holder
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-Beaker
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-Tape! !
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-Goggles
-Hot Plate!!
-Distilled H2O! !
Procedure:!
In this lab, we were observing whether the quantity of glucose solution would effect the rate at which cellular respiration occurs at within the tested yeast. One-by-one, different quantities of glucose solution was added to the corresponding test tubes followed by 6 drops of the 0.005% methylene blue solution. 5 mL of 20% yeast suspension was then added to each test tube .
Each tube was placed in the hot water bath and timed to see which reaction would have the greatest alteration on the indicator’s colour (bright blue to clear) within a 5 minute time-frame.
The reactions were then rated on a scale of 0-5 (0 being most un-reactive, 5 being most).!
1. 4 test tubes were placed in a test tube holder.!
2. 6 drops of the 0.005% methylene blue solution was added in each test tube.!
3. 3mL of water was added to the control test tube.!
4. 3mL of the glucose solution was added to the first of the four test tubes.!
5. 6mL of the glucose solution was then added to its respective test tube.!
6. 9mL of the glucose solution was added lastly into it’s respective test tube.!
7. Each tube was labelled with the corresponding quantity of glucose solution (0mL(control),
3mL, 6mL, 9mL,)!
8. 5mL of 20% yeast suspension was added to each of the test tubes, then immediately placed in a hot water bath, with timing commencing immediately.!
9. each reaction was carefully observed, with the timing stopping immediately after the five minute time-frame.!
10. Reactions were rated on a scale of reactivity ranging from 0-5 (0 being least, 5 being greatest)! 1

Observations:!
Amount of glucose

Reaction rating based on colour-change (0-5)

0mL of glucose (control)

No change (0)

3mL of glucose

2 (lower)

6mL of glucose

3(middle)

9mL of glucose

5(most)

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The Effect of Glucose on The Cellular Respiration Within Yeast:
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Rate of Reaction Scale

3.75

2.5

1.25

0

0mL

3mL

6mL

9mL

Amount of Glucose Solution

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During the reaction, I observed that when the quantity of the glucose solution was increased the rate of reaction increased respectively. Therefore there was a correlation in-between the quantity of glucose solution and rate of reaction. Referencing the graph above, the test tube containing 9mL was clearer after five minutes compared to the other test tubes containing lesser quantities of the solution, this reinforces the observations already stated.!

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Results:!
After completing the experiment, I observed that 9mL of 0.005mol/L glucose solution allowed for the largest amount of cellular respiration within the yeast molecules to occur. With an increase of glucose solution, the rate of reaction within the 20% yeast suspension will increase correspondingly.! Discussion:!
For us to survive, we need energy for our bodies to function. Energy at it’s simplest form happens at a cellular level. Cellular respiration is the way our bodies and any living organism creates energy. This process takes place within the mitochondria of every living cell. Cellular respiration is the oxidization of a glucose molecule. Through oxidizing the sub-molecule, pyruvate, we create two electron carriers,NADH and FADH2 which are carriers for H+ ions.
NADH and FADH2 are then carried to the electron transport chain where enzymes breakdown the coenzymes to create ATP (Adenosine triphosphate), a high energy molecule that our body uses to provide us with energy. Our energy is generally produced through aerobic respiration.
The product of reacting glucose and O2 yields CO2, H2O and energy (ATP). The general formula for this reaction goes as following:!
C6 H12 O6 + 6 O2 ==> 6 CO2 + 6 H2O + Energy
During the entire cellular respiration cycle, roughly 34 molecules of ATP are created within the electron transport chain and 4 within glycolysis and Krebs cycle. This process can be difficult to grasp, so the best way to fully understand the process it to be able to view the visual effects.
Like us, yeast, a microscopic eukaryotic fungus, goes through cellular respiration to produce energy. What differentiates us from yeast is that yeast goes also goes through anaerobic

and aerobic respiration, depending on the environment it’s in. Anaerobic respiration creates energy without the presence of Oxygen. The breakdown of glucose is catalyzed by the enzyme zymase, rather than by being oxidized like in aerobic respiration. The products produced in this reaction are C2H5OH (ethanol), CO2 and energy (ATP). The general formula for this reaction is as follows:!
C6 H12 O6 ==> 2 C2H5OH + 2 CO2 + Energy
Since yeast goes through a form of cellular respiration, I was able to visualize the reaction occurring during the cellular respiration with the presence of methylene blue solution.
Methylene blue solution accepts the hydrogen ions that are released during the reaction, turning the solution clear when it has accepted all possible hydrogen ions. Therefor, we knew the experiment was working when we were able to see the colour change in the methylene blue solution. Yeast has a natural storage of glucose which allows for the reaction to occur but at a slower rate. During our experiment, I observed that with an increase in the quantity of glucose solution, the faster the methylene blue turned from it’s natural blue state to clear. By adding the glucose solution I was able to speed up the process because there was a greater quantity of glucose for the enzyme zymase to bind to.With glucose acting as a substrate, there was more bonding sites for the enzyme to bind to, allowing for more reactions to occur simultaneously. Referring to the graphs on page two with the data collected during the experiment, I was able to come to the conclusion that with an increase of glucose there was an increase of reactivity, this being because of an optimal environment being created for the

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enzyme. While more substrates created an optimal environment for the enzymes reactivity, the optimal temperature of 32c created an even more suitable environment for the enzymes to function in. A few sources of errors during the course of the experiment was the quantity of the yeast, methylene blue and glucose solution added. The temperature also played a role in the source of errors because I had to experiment with the optimal temperature for the reaction to occur at. Finally, exact timing appeared to be difficult because the reactions occurred at a more lengthy time than I expected.

Conclusion:
In conclusion I discovered that with an increase of glucose solution the reactivity rate at which cellular respiration occurs at within the 20% yeast suspension increases as-well. Therefore, the higher quantity of a glucose based solution given to yeast, the faster the rate-of-reaction will occur.! !

Bibliography:!
"Electron Transport." - Chemwiki. N.p., n.d. Web. 16 Oct. 2014.

SparkNotes. SparkNotes, n.d. Web. 16 Oct. 2014.

"Aerobic Respiration in Pelagic Marine Sediments." Deep Sea Research Part B. Oceanographic
Literature Review 29.12 (1982): 764. Web.

"Meaning of NADH in Biology?" Answers. Answers Corporation, n.d. Web. 16 Oct. 2014

"What Is Yeast?" Explore Yeast – All You Have to Know about Yeasts. N.p., n.d. Web. 16 Oct.
2014.

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Bibliography: ! "Electron Transport." - Chemwiki. N.p., n.d. Web. 16 Oct. 2014. SparkNotes. SparkNotes, n.d. Web. 16 Oct. 2014. "Aerobic Respiration in Pelagic Marine Sediments." Deep Sea Research Part B. Oceanographic Literature Review 29.12 (1982): 764. Web. "Meaning of NADH in Biology?" Answers. Answers Corporation, n.d. Web. 16 Oct. 2014 "What Is Yeast?" Explore Yeast – All You Have to Know about Yeasts. N.p., n.d. Web. 16 Oct. 2014. 4