cell respiration lab

cell respiration lab - Jared Head February 26, 2007 Biology...

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Jared Head February 26, 2007 Biology 107 Aerobic Respiration Using DCPIP as an Alternate Electron Acceptor, Fermentation of Yeast, Fermentation of Other Carbohydrates, and the Factors That Affect These Processes Introduction Cellular respiration is one of the most important processes in biology because it is responsible for creating the energy that fuels cells and their composite organisms. Put simply, without cellular respiration, there would be no life. Cellular respiration is a series of catabolic, enzymatic reactions that break down a carbon source to form adenosine triphosphate. The two types of cellular respiration that were investigated in this experiment were aerobic respiration and anaerobic respiration, or fermentation. Aerobic respiration, which is the most common and efficient catabolic pathway, involves the use of oxygen to convert organic compounds into usable energy for the cell (Campbell and Reece 161). The carbon source is usually glucose, and the product yield is anywhere from 36 to 38 ATP molecules per molecule of glucose. The reaction usually looks as follows: “While glucose is the energy source for most cellular activity, the cell cannot use it as an intact molecule” (Lombard and Terry 121). The bonds holding the carbohydrates together must be broken down through a complex series of enzymatic pathways,
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including glycolysis, the Krebs cycle, and the electron transport system. Specifically, the Krebs cycle was investigated in this experiment. Because the Krebs cycle takes place in the mitochondrial matrix, a mitochondrial suspension was utilized examine the conversion of succinate to fumarate. “This reaction reduces FAD to FADH 2 , which produces free electrons that normally enter the electron transport chain” (Lombard and Terry 161). To measure the amount of electrons released, an alternate electron acceptor, dichlorophenolindophenol, or DCPIP was provided. Instead of allowing the electrons to enter the electron transport system, the DCPIP dye “snatches” them on the way. Because DCPIP is blue in its oxidized state and colorless in its reduced state, we can measure the reaction by quantifying the amount of electrons it accepts. As DCIPIP becomes more reduced, it also becomes more colorless and facilitates higher transmittance. Because transmittance measures the loss of color, which is indicative of increased reaction, its percent value was measured with a spectrophotometer to quantify the reaction. Another catabolic pathway studied in this experiment is fermentation, a “partial degradation of sugars” (Campbell and Reece 161). Unlike aerobic respiration, fermentation does not utilize oxygen to metabolize glucose. Although this lack of oxygen may at first make fermentation seem like a more efficient process, it only allows for the production of two ATP molecules per molecule of glucose. Fermentation follows this general chemical formula:
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Fermentation can have the byproducts of lactic acid, carbon dioxide, and ethanol. Lactic acid buildup in muscle cells is responsible for the painful sensation one feels after
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cell respiration lab - Jared Head February 26, 2007 Biology...

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