Cell Respiration Lab

Yeast Cell Respiration Lab

Group members: Sean Yang, Andrew Mao

Abstract
In order to understand the process of cell respiration and how temperatures could affect it, we have created a lab using the fungi yeast to observe the process of cell respiration under different temperatures.

Introduction
Cell respiration occurs in all living cells, and is the process in which organisms produce ATP energy from glucose, with byproducts of carbon dioxide and water. ATP is the energy which cells function upon. Yeast is a type of fungi which can respire only with the presence of oxygen and glucose. Under different environments, yeast will respire differently.

Glucose + Oxygen → Carbon Dioxide + Water

C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O

Hypothesis:
Due to increased molecular movement when under heat, it is likely that cell respiration of yeast will occur at a faster rate due to the fast movement of particles at high temperature.

Materials: Sugar, water, yeast, salt, scale + weighing paper, graduated cylinders, 3 thermometers, 3 airtight syringes, 3 test tubes, an ice box and a warm dry heating bath.

Procedure:

1. Obtain 3 separate set of measurements of 35ml water, 1g of sugar, 1g of yeast and 0.2g of salt.

2. Obtain 3 separate test tubes and mix all contents evenly into the 3 test tubes.

3. Stir up the contents in each test tube and let them all sit for 5 minutes.

4. This step must be done quickly and simultaneously: after 5 minutes, immediately put the airtight syringe over each test tube, make sure there are 2ml of air where the syringe is not losing any gas (airtight).

5. Quickly put each test tube at their locations: one out in the open, one in the ice box, and one in the heat bath.

6. Collect the change (reading minus 2ml) in ml of gas every 1 minute for a total of 5 minutes.

7. Stick thermometers into the ice box and the warm bath to note their temperature.

Safety

-The warm dry heating bath shouldn't be too hot (50 degrees), but don't stick any body parts in just in case.

-Yeast makes a disgusting smell after fermentation, keep away from nose, mouth, eyes and hopefully clothes.

-Test tubes are made of glass, be careful when shoving the syringe into the test tube, don't use too much force, you might shatter it in your hand.

Results

Conclusion
As the graph shows, CO2 produced by yeast cell respiration increases in a much faster rate when at warm temperature. At cold temperature, there is almost no CO2 formed as we believe the enzyme have denatured due to the cold. This is evidence to confirm our hypothesis that cell respiration occurs at a more rapid rate at higher temperatures, we believe that this is due to faster particle movement at higher temperatures.


Revision (2014/3/09):
After having my lab report checked up by my teacher, I realized I was lacking in many parts...so below I will provide additional information to explain the phenomenon that has occured in this lab.

Background Information:
Cell respiration is a complicated process occurring in a cells cytoplasm and mitochondria where cells utilize glucose to produce ATP energy in order to function. Cell respiration has numerous steps and each small process is powered by a different type of enzyme. We have learned in class that enzymes are "catalysts" for the cell and lower activation energy/speed up each small step in cell respiration. We have also learned that when under abnormal temperatures (every enzyme has an ideal temperature) enzymes will denaturalize and fail to achieve their catalyst effects. Our yeast cell respiration lab will test the effectiveness of enzymes under different temperatures by monitoring the amount of CO2 produced when yeast cells go through cell respiration.

Hypothesis rewrite:
If the temperature of the environment in which the yeast is in increases, then we can expect a faster rate of cell respiration and faster rate of CO2 emission; this is because yeast molecules under heat will increase their molecular movement and enzymes will catalyze a chemical reaction at a faster rate.

Conclusion Rewrite:
Although we have not tested a large enough range of temperatures to find the ideal temperature for yeast cell enzymes to undergo cell respiration, we have discovered through our data and graph that the warmer the temperature, the more effective the enzyme and thus the more CO2 produced from respiration. We have proven our hypothesis to be correct as the higher the temperature, the more CO2 we have gotten and the faster rate at which enzymes operate due to increased molecular movement speed.