Lactic Acid Fermentation Lab Report

In this experiment, we strove to determine how effective different sugars were in fermentation by measuring their CO2 emissions. An increased CO2 production implies the substrate is undergoing glycolysis more often, resulting in increased ATP synthesis. For a more accurate interpretation of the results, glucose acted as a positive control, displaying the most efficiency in fermentation as shown in Figure 1 and Figure 2, while ethanol, which is a byproduct of fermentation, acted as a negative control, producing no CO2. These controls were necessary in order to compare the effectiveness of alternative substrates ATP production when presented with S. cerevisia.
It was hypothesized that the monosaccharides galactose and fructose would elevate
Cells rely on processes such as cellular respiration and fermentation in order to produce ATP through a series of steps. There are two different types of fermentation: lactic acid fermentation in humans and alcohol fermentation in yeast and bacteria. All of these processes synthesize ATP, however, unlike respiration, both types of fermentation occur when oxygen is not present. In addition, each process undergoes a critical first step, specifically glycolysis which converts glucose to pyruvate which is then converted to carbon dioxide and ethanol, regenerating NAD+, an electron carrier necessary for the continuation of glycolysis. The sugar must be present to be broken down into two molecules of pyruvate and the potential energy is released to phosphorylate ADP to ATP. However, alternative carbon sources may be substituted for glucose, resulting in ATP with ethanol and CO2 as byproducts, although more complex molecules will require additional steps in order to ferment. Our hypothesis was that artificial sweeteners such as Splenda and Xylitol, would produce less CO2 than the monosaccharides fructose and galactose, given their composition, when presented with the yeast species, Saccharomyces