Lab 04: Sugar Respiration in Yeast
Sugars are vital to all living organisms. The eukaryotic fungi, yeast, have the ability to use some, but not all sugars as a food source by metabolizing sugar in two ways, aerobically, with the aid of oxygen, or anaerobically, without oxygen. The decomposition reaction that takes place when yeast breaks down the hydrocarbon molecules is called cell respiration. As the aerobic respiration breaks down glucose to form viable ATP, oxygen gas is consumed and carbon dioxide is produced. This lab focuses on studying the rate of cellular respiration of saccharomyces cerevisiae, baker’s yeast, in an aerobic environment with glucose, sucrose, lactose, artificial sweetener, and water as a negative control. A CO2 Gas Sensor Probe is used to measure the amount carbon dioxide produced as the cellular respiration occurs which is proportional to how much of the molecule is decomposed. For this experiment water is used as a treatment control to provide a baseline for all the other treatments. To ensure the validity of the experiment, the amount of time the yeast was exposed to the sugars, the designated pipets for each sugar, the amount of sugar tested, and the temperature of the yeast culture were monitored to be the same throughout the experiment.
It was hypothesized that during the cellular respiration glucose, sucrose, splenda, and lactose would all produce carbon dioxide but in various amounts. Since the Splenda used is an artificial sweetener, it was also hypothesized that it would produce the least amount of carbon dioxide of the sugar samples but since water is used also as a control, it should have the lowest to zero reading of all the samples since it contains no sugar. Due to the different molecular formula of glucose, sucrose, and lactose it was also hypothesized that the cellular respiration between the yeast and glucose would create the most amount of carbon dioxide being that it is a monosaccharide that it should require...
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