1. SUGAR SUBSTITUTE EFFECT ON YEAST RESPIRATION
By: Peter Szalay
Grade 9
Central Catholic

2. Cell Respiration

3. Sucrose (C12H22o11)
Disaccharide of glucose and fructose Linked via their anomeric carbons.
Produced naturally in plants eg. Sugar cane or sugar beet.
functions as an energy store for metabolism and as a carbon source for biosynthesis.
Most common sweetener in the modern world

4. Sucralose (C12H19Cl3o8)
Artificially created sweetener and is a sugar substitute
Non-caloric due to the body not being able to metabolize it
1,000 times sweeter than sucrose

5. Saccharomyces cerevisiae (Bakers Yeast)
Best known for alcohol fermentation and bread baking.
Yeast is the most investigated cell in the world.
Used in microbiology due to its ease of manipulation and rapid growth.
Eukaryotic, shares biochemistry with more advanced organisms.

6. Purpose
To investigate sucralose effect on yeast respiration.
Hypotheses
Alternate Hypothesis: The yeast will be able to metabolize sucralose yielding more CO2 than the control.
Null Hypothesis: The yeast will not be able to metabolize the sucralose more than the control.

7. Materials Rapid Rise Saccharomyces cerevisiae, Red Star brand
Micro Pipettes
Macro Pipettes
Balloons (9” Rounds)
125 ml Erlenmeyer Flasks
Deionized Water
Sucrose
Sucralose
100mL Graduated Cylinders
Plastic Tub
Plastic Film Wrap

8. Procedure
The Sucrose and sucralose were dissolved in sterile water at a concentrations of (10%).
The sugar solutions were added to 5 flasks each in the ratios as seen below. 
2.5 grams of Red Star rapid rise Cooking Yeast was added to each flask and balloons were immediately affixed to each flask.
The flasks were transferred to a warm (35 C) water bath.
After 60 minutes of incubation, each balloon was removed from the flask (careful to prevent any leakage of gas; each balloon was pinched at the neck and twisted off).
A plastic tub was filled with water.
Each graduated cylinder was filled with water to the brim and sealed with plastic wrap.
The cylinder was inverted and immersed into the water and the plastic wrap removed.
The balloon was placed into the water with the mouth placed into the cylinder.1
The mouth was slowly released and the air was pumped into the graduated cylinder.  The volume of gas was then recorded.

9. Solutions 0% Sugar 0.2% Sucrose 2% Sucrose 0.2% Sucralose 2% Sucralose
Yeast
2.5g
Sucrose Stock
(10%)
0ml
0.8ml
8ml
Sucralose stock (10%)
Distilled Water
40ml
39.2ml
32ml
Total Volume
Solutions

11. Carbohydrate effect on Yeast Respiration P = 1.891 x 10–12

12. Dunnett’s test (Whole Set)
Sugar Concentration
Math
T-value
Conclusion
(t-crit 3.48)
0.2%
Sucralose
0.216
Not significant
2% Sucralose
0.993
0.2% Sucrose
1.273
Not Significant
2% Sucrose
15.494
Significant

13. Conclusions Fail to reject the null hypothesis
Dunnett’s test showed that there was not a significant difference between the control and either of the tests of sucralose.
Also, there was a significant difference between 0.20% sucrose and 0.20% sucralose, and a difference between 2% sucrose and 2% sucralose.

14. Limitations of project
Slight variation in when data was recorded
A larger sample size would be needed to get more accurate data.
Not all the CO2 that was produced by the yeast rose into the balloon.

15. Extensions to the project
The sugars can be tested for the survivorship of the yeast
Other types of carbohydrates can be tested on their effects on yeast respiration.
Other compounds such as honey can be tested for their effect on yeast as well
Test for yeast cell population growth
Test for other health factors in yeast

16. References
Otterstedt, Karin et al. “Switching the mode of metabolism in the yeast Saccharomyces cerevisiae” EMBO reports vol. 5,5 (2004):
“Effect of Different Isomers of Sugar on Yeast Respiration.” California State University, Northridge, Nov. 2005,
“Basic Science: Understanding Experiments.” OpenLearn, The Open University,
Libretexts. “Cellular Respiration.” Biology LibreTexts, Libretexts, 20 Feb. 2016, bio.libretexts.org/Ancillary_Materials/Experiments/General_Biology_Labs/Cellular_Respiration.
Kayikci, Ömur and Jens Nielsen. “Glucose repression in Saccharomyces cerevisiae” FEMS yeast research vol. 15,6 (2015): fov068.

17. CO2 amount recorded 0% Sugar 0.2% Sucrose 2% Sucrose 0.2% Sucralose
8ml
21ml
125ml
13ml
22ml
24ml
128ml
14ml
23ml
15ml
27ml
155ml
17ml
28ml
186ml
18ml
30ml
195ml
19ml
25ml

18. ANOVA (Whole set) Summary of Data Treatments
0% 0.2% SR % SR % SL 2% SL Total N ∑X
Mean ∑X
Std.Dev
Result Details
Source SS df MS  
Between-treatments F =
Within-treatments   p=1.891 x 10–12
Total    

19. ANOVA comparing 0.2% concentrations
Summary of Data
0.2% SL % SR Total N ∑X
Mean ∑X
Std.Dev
Result Details
Source SS df MS  
Between-treatments F =
Within-treatments   p=
Total  

20. Anova comparing 2% concentrations
Summary of Data
Treatments
2% SR % SL Total N ∑X
Mean ∑X
Std.Dev
Result Details
Source SS df MS  
Between-treatments F =
Within-treatments   p=1.428 x 10-5
Total