Dean Cutrer
March 25th, 2020
Fermentation
Introduction:
One of the principles of Biology is that all living things use energy. Plants produce chemical
energy in a process called photosynthesis. Plants are autotrophs. They make their own
organic molecules from sunlight and inorganic sources. Animals and many other organisms
obtain our energy by eating or breaking down already formed organic molecules. These
organisms are heterotrophs.
All cells use the nucleotide adenosine triphosphate (ATP) to power most cellular
processes. The process of converting chemical energy of organic molecules into ATP is called
cellular respiration. There are various kinds of cellular respiration. The most successful type
is aerobic respiration. Aerobic respiration uses oxygen and is the type of respiration used by
most large organisms.
Aerobic respiration breaks down glucose to form large amounts of ATP in four stages.
The first is glycolysis which is carried out in the cytoplasm or cytosol of most living things and
converts glucose in to two molecules of pyruvate. The second stage is the breakdown of
pyruvate to form acetyl-CoA followed by the third stage which is citric acid cycle or Krebs
cycle. The Citric acid cycle happens in the mitochondria of a eukaryotic cell. During these
reactions, high-energy electrons are transferred in a series of oxidation —reduction
reactions. These electrons are then used in the fourth stage of aerobic respiration, electron
transport which produces most of the ATP made. At the end of the electron transport, chain
oxygen accepts the electrons and is reduced.
When oxygen is limiting many organisms have other options for respiration. One of
these anaerobic pathways is fermentation. In fermentative pathways glycolysis is still used
to produce pyruvate. The pyruvate can then be converted to either lactic acid or carbon
dioxide and ethanol. This process will produce a small amount of ATP. For each molecule of
glucose that goes through fermentation two ATPs are produced. Lactic acid fermentation
occurs in some human cells such as muscle tissue. Microorganisms such as yeast often use
acholic fermentation which is important in baking and in the brewing of beer and wine
making.
Purpose/Objective:
This experiment is designed to examine the effect of different variable on the rate of
fermentation. The yeast in this experiment will ferment their carbon source to form CO2 and
ethanol.
My hypothesis is that there will be a increase in the yeast change for week two compared
to the week one yeast.
Null Hypothesis: Nothing will change
Materials:
• Fermentation tubes
• Balance
• Yeast
• Sugar
• Water
• Weigh boats and spatulas
• Ruler (if fermentation tubes not graduated)
• Stir rod
Methods/Procedure:
Week 1:
1. Each group will weigh out 0.2 g of yeast.
2. Weigh out 0.5 g of sucrose.
3. Add yeast and sucrose to 10 mL of warm water and mix with a stirring rod.
4. Pour yeast and sugar mix into fermentation tube.
5. Cover the opening of the fermentation tube and invert the tube so the long portion of the
tube fills with the solution.
6. After ten minutes measure the distance from the top of the fermentation tube to the top of
the solution and record the distance in centimeters or millimeters.
7. Repeat steps 5 and 6 every ten minutes until six measurements are made or until no more
measurements are possible.
8. When finished measure the width of the tail portion of the fermentation tube.
9. Calculate the radius or the tail portion of the fermentation tube. (The radius is 1/2 the
diameter or width)
10. Use the formula 7tr2 to calculate the cross-sectional area of the fermentation tube.
11. For each ten-minute interval, multiply the distance recorded by the cross-sectional area to
find the volume of the carbon dioxide.
12. Clean up.
Week 2: Repeat with different variables from TA
Results:
Week 1 10 min 20 min
Distance 0 cm
0 cm
Volume 0
0 cm^3
cm^3
Week 2
10
min
Distance 2.4
cm
Volume 2.7
cm^3
30 min
1.0 cm
1.1
cm^3
20
30
min
min
6.0 cm 8.5 cm
6.8
cm^3
9.6
cm^3
Week 1:
Average/Mean: 0.33333333
Median: 0
Mode:0
STND: 0.57735027
P.Value: 0.04230802
Week 2:
Average/Mean: 5.63333333
Median: 6
Mode: N/A
STND: 3.0664855
P.Value: 0.04230802
Conclusion:
After conducting the experiment, the P.value is .04 which means we can reject out null
hypothesis. My hypothesis stating that the yeast for week two will have a higher increase than
week one was correct.
Yeast Fermentation
Distance in CM
10
8
6
4
2
0
1
2
3
Time in Minutes Per (10)
Week 1
Week 2