The Ability of Yeast to Ferment Sugar Molecules

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INTRODUCTION:

All cells need to have a constant energy supply. The two processes by which this energy is attained from photosynthetic materials to form ATP are cellular respiration and fermentation. (Hyde,2012). Fermentation is a way of harvesting chemical energy that does not require oxygen. (Reece et al. 2012). When the body is deprived of oxygen it will then begin to meet its energy needs through the slow process of fermentation. In our lab we investigated alcoholic fermentation by using yeast, which can flourish in an low energy environment in anaerobic conditions.

In this lab our goal was to discover the rate at which yeast will ferment different sized molecules of carbohydrates. In order to perform our experiment we made use of water, glucose, sucrose, and starch. It was hypothesized that glucose, sucrose, then starch would all be used to produce energy during fermentation. Being that glucose is a simple sugar, or monosaccharide, we predicted that glucose would be fermented most quickly. This hypothesis was made based on the idea that glucose is the cell's main source of energy in aerobic cellular respiration. The first step of cellular respiration is glycolysis which breaks down glucose for energy. We predicted that Sucrose would ferment second to glucose since it is a larger molecule composed of glucose and fructose. Finally, we predicted that starch would ferment extremely slow behind all of the other carbohydrates.

METHODS AND MATERIALS:
On October 31, 2012 in the lab of Greenfield Community College my lab partners, Madeline Hawes, Timothy Walsh and I conducted the following experiment in order to test the effectiveness of yeasts' ability to ferment different carbohydrates. We first filled 6 small flasks with 75 ml of water and 5 drops of phenol red to each flask. Four of these were labeled with the solution that would feed into them and the other two with “control” and the last with “increased CO2.” The color of phenol red is...
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