Cellular Respiration Lab
Names:
Objective
To examine cellular respiration by observing aerobic and anaerobic respiration of yeast in an enclosed fluid
environment.
Background
Mitochondria are the cells' power sources. They are the second largest organelles. Mitochondria are generally
rod-shaped, with a double-layered outer membrane with inner folds called cristae. Energy-producing chemical
reactions take place on cristae. Chemical energy is stored in the chemical bonds of glucose. This energy is
transferred into ATP molecules though the process of aerobic respiration. Aerobic respiration is broken down
into three processes. The first process is glycolysis, which occurs in the cytoplasm. The second process is the
Kreb's cycle, which occurs in the mitochondrial matrix. The last process, called the electron transport cycle,
occurs in the inner mitochondrial membrane.
Yeast is a facultative anaerobe*. If no oxygen is present in their environment, they will respire anaerobically.
ATP will be made during glycolysis. This requires no O2. To regenerate the NAD+ needed for glycolysis, the
yeast will undergo alcoholic fermentation. At this point, CO2 is produced.
* Faculative anaerobe means that it can survive with or without oxygen. It just switches from aerobic to anaerobic (alcoholic) respiration.
* Obligate anaerobes will die in oxygen.
Materials
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Test tube with screw top lid (you don't need the lid)
Yeast solution
30 mL each of the following liquids (seven up, apple cider, grape juice)
Latex balloon
10 mL graduated cylinder
50 mL graduated cylinder
String and ruler
Test tube rack (you may have to share)
Large Beaker
Procedure
1. Get test tube, test tube rack and balloon
2. Put 5 ml of yeast solution in your test tube
3. Blow up your balloon a few times so it will stretch out.
4. Pour 30 ml of one of the liquids into your test tube. Close the test tube with your finger and shake it gently.
5. Immediately put the balloon over the test tube top and place test tube in beaker of warm water.
6. Wait 10 minutes and use the string and ruler to measure the circumference of the balloon. Record on the data
table.
7. Write down any observations as well (like: did it bubble,color, smell etc)
8. Remove the balloon, rinse out the test tube and repeat the above steps for the other 2 liquids.
9. Rinse out the test tubes a final time, clean your lab area, return any materials to where you got them.
Data Table
Liquid Type
Circumference of balloon in cm
after 10 minutes
Observations
Seven-Up
Grape Juice
Apple Cider
Conclusion Questions:
1. Which liquid provided the greatest food (sugar) source? Explain your answer.
2. What is the difference between aerobic and anaerobic respiration?
3. Did the yeast undergo aerobic or anaerobic respiration in this activity? How do you know?
4. How many molecules of ATP were produced for every molecule of glucose during this activity?
5. How many of these ATP molecules were produced from the process of glycolysis?
6. How many of these molecules of ATP were produced from one molecule of glucose during the Kreb's cycle?
7. How many of these ATP molecules were produced in the electron transport system?
8. Predict what would happen if we left the liquids in the test tubes for 2 days. (We will leave a class set out)
9. Predict what would happen if left the liquids in the test tubes for 2 weeks.