Yeast Cell Metabolism Lab - Pottsgrove School District



Biologist ____________________________ Date _________________

Yeast Cell Metabolism Lab

Objective

You will be demonstrating the differences in the metabolic rate of yeast with a variety of energy sources.

Materials

- 1 pack of yeast

- 3 Erlenmeyer flasks

- Water

- Salt

- Sugar

- Sugar Substitute

- 3 Balloons

- Labels and a marker

Pre-Lab Questions

1. Define Autotroph and Heterotroph.

2. What does ATP stand for? What is converted to make this energy?

3. What is aerobic respiration?

4. What is anaerobic respiration, fermentation?

5. Compare and contrast fermentation and cellular respiration.

Procedure

1. Label your Erlenmeyer flasks

a. Salt

b. Sugar

c. Sugar Substitute

2. Fill each of the bottles with 50ml of water at 35oC (Room Temperature)

3. Add 1/3 of a packet of yeast to each of the three flasks.

4. Add a tablespoon of salt to the “salt” flask, a tablespoon of sugar to your “sugar” flask, and a tablespoon of sugar substitute to your “sugar substitute” flask.

5. Swirl the flask to be sure the yeast has access to the energy source.

6. Attach the balloons to the tops of the flasks.

7. Make an initial observation and record on table one what you see again every 5 minutes for 30 minutes.

Table One – Yeast and Energy Source

|Time |Salt |Sugar |Sugar Substitute |

|Initial | | | |

|5 min | | | |

|10 min | | | |

|15 min | | | |

|20 min | | | |

|25 min | | | |

|30 min | | | |

Conclusion Questions

1. In which of your yeast food source experiments did the yeast show the most activity? Why?

2. Based on what you know about anaerobic and aerobic respiration, which was happening in the flasks? How do you know?

3. What filled the balloons in your experiment?

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