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Enzyme Reaction of Different Yeast Substances

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Title: Enzyme Reaction of Different Yeast Substances


In this lab, my group was able to learn and understand the process of cellular respiration. Our goal in this lab was to find out which solution reacted most with the enzymes in the yeast. The effects of inhibitors on enzymes and the activity of yeast on different solutions were measured in this lab. In lecture, we learned that fermentation enables some cells to produce ATP without the use of oxygen. There are three steps to cellular respiration: In chemical reactions, the molecules at the beginning of the process are called substrates and the end molecules after the reaction are called products. Fermentation takes place during glycolysis. In this lab we were able to measure glycolysis reactions under anaerobic conditions. Glycolysis begins the degridation by breaking glucose into two molecules of pyruvate, The Citric Acid Cycle takes place in the mitochondrial matrix decomposes a derivative of pyruvate to carbon dioxide. Oxidative phosphorylation is powered by redox reactions that transfer electrons from food to oxygen. The set of enzymes made in a cell determines which metabolic pathways occur in that cell. This means that there will be more of a reaction with a certain solution of enzymes in the environment with the increased temperature. Inhibitors are molecules that decrease enzyme activity, and activators are molecules that increase activity... Drugs and poisons are often enzyme inhibitors. Enzyme activity is also affected by temperature, pH, and the concentration of substrate. (Campbell et al. 2002). In this lab, our group recorded the reaction of different enzymes in a yeast solution with a steady temperature by measuring the airspace in the tubes. In this lab, my experimental hypothesis is that the reaction rate shown in the airspace measurements will not increase because it is the receiprocal. If this is true, then it will show in the graph as an upward slope with the percentage of absorbance going up as the pH level goes up. The null hypothesis is that the reaction rate or pH absorbance will not be affected at all by the level of pH being tested.

Materials and Methods:

In this lab, we recorded the reaction of enzymes in a yeast solution by measuring whether the airspace increases or decreases. In this lab, we used a water bath, test tubes, colored tape, yeast, drying cloth, syringes, and a timer. The water bath was set at an optimal temperature of 37 degrees celsius and was left to warm. During this time, tubes 1-5, each tube was marked with the appropriate labels using the colored tape, and filled with 10mL DI H2O, 5mL 5% glucose and 5mL DI H2O, 5mL 5% glucose and 5mL 0.01M NaF, 5mL 5% glucose and 5mL 0.05M NaF, and 5mL 5% glucose and 5mL 0.10M NaF. The Test tubes were each covered with another larger test tube and it was flipped. Next, the initial volume and airspace were measured before being put into the water bath. We took the previously recorded number and divided it by the total length of the test tube for each test tube. They were then measured for the airspace in millimeters at intervals of fifteen minutes for one hour. The next step was to convert each of our findings from millimeters of airspace to milliliters of CO2 produced. We then converted the results of our airspace by multiplying the millimeters of airspace by the conversion factor. The formula we used for this step was taking the millimeters of airspace and multiplying by the conversion factor which equaled out to the milliliters of CO2 produced.


Tube Initial 15 Min 30 Min 45 Min 60 Min

1 0 .1 .13 .17 .19

2 0 .90 .60 -.60 -.77

3 0 -.30 .75 1.65 1.9

4 0 .60 1.05 3.15 3.85



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