Fermentation in Yeast

Fermentation in yeast

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Alicia Portillo

BIO 111-09

Lab Report

12/02/2015

Fermentation in Yeast

Introduction:

Yeast is a single celled organism that leads fermentation when sugars are present to make chemical energy and in the process produce carbon dioxide as the product of fermentation. Carbon dioxide gas accumulates as a waste product of fermentation in yeast and also cellular respiration. Yeast can metabolize sugars in 2 differents ways: aerobically (using oxygen) and/or anaerobically(without oxygen). Since yeast leads to fermentation it metabolizes sugars anaerobically.

The goal for the student in this lab was to measure the production of carbon dioxide by yeast in order to acquire more knowledge on metabolism and fermentation.On this experiment Yeast was added to 4 different solution with different amounts and were inverted in pre-warmed water for 10- minute intervals for 40 minutes to measure the gas that was produced by the yeast and then the rate of CO2 production was calculated.

It is expected that the more amount of sugar, the more gas will be produced since sugar is the source of food for the yeast. I predict that 1.5% glucose will be the solution with the highest gas produced in yeast, and 1.0% lactose will be the solution with the lowest gas production in yeast due to the fact that yeast is unable to metabolize lactose since they do not have an enzyme to directly breaks lactose into sugars this is because yeast only breaks complex carbohydrates into simple sugars and lactose is a double sugar composed of glucose and galactose. that why I predict that there isn’t going to be that much gas produced from the lactose solution.

Materials and Methods:

In order to realize this lab, the student had to label and fill 5 test tubes with the following solutions: tap water, 0.5% glucose, 1.5% glucose, 1.0% lactose, and 1% lactose plus 5 drops of lactase