Cellular Respiration Of Yeast Scientifi

Topics: Glucose, Enzyme, Carbon dioxide Pages: 8 (1974 words) Published: November 15, 2014
ABSTRACT

The effect of inorganic cofactor such as Magnesium to the rate of respiration of yeast was determined using Durham tube assembly with the substrate glucose. After thirty minutes, the test tube with the cofactor in the form of Magnesium sulphate MgSO4 showed the higher amount of carbon dioxide evolved which was measurable through volume and was one of the by- products of cellular respiration. This stated that the higher amount of CO2 evolved, the higher the rate of respiration. Thus, the hypothesis “If enzymes need cofactors to speed up its function, cofactors affect the rate of cellular respiration.” was accepted. Smith fermentation tube assembly containing 15 ml of 10% yeast concentration with different substrates was used to test the hypothesis “If the nature of substrates affects the cellular respiration in yeast, then the simpler the substrates the faster the cellular respiration.” The height of the area of the tube occupied by CO2 was measured to get the volume after thirty minutes. The result showed that sucrose had evolved the greatest CO2, followed by fructose, glucose and starch respectively while lactose and distilled water got no CO2 evolved. Thus, the result concluded the before mentioned hypothesis.

INTRODUCTION
Cellular respiration is a process in which cells produce the energy they need to survive. Cells use oxygen to break down the sugar glucose and store its energy in molecules of adenosine triphosphate (ATP). Cellular respiration is critical for the survival of most organisms because the energy in glucose cannot be used by cells until it is stored in ATP. Two critical ingredients required for cellular respiration are glucose and oxygen. Although most organisms on Earth carry out cellular respiration to generate ATP, a few rely on alternative pathways to make this vital molecule. These pathways are anaerobic—that is, they do not require oxygen. Fermentation is a type of anaerobic pathway used by certain species of bacteria that live in anaerobic environments, such as stagnant ponds or decaying vegetation. Some cells produce ATP using both anaerobic and aerobic pathways(Lagunzad, 2004). For example, muscle cells typically carry out cellular respiration, but if they do not receive enough oxygen, as can occur during strenuous exercise, muscles switch to fermentation. In this paper, yeast cells, unicellular microorganisms, are used as the working organisms to determine the effect of cofactors and substrates on the rate of respiration. They carry out both pathways, depending on whether they are in an aerobic environment, such as soil, or an anaerobic one, such as inside a wet lump of dough.

Figure 1. The structure of unicellular organism, yeast

Cellular respiration was catalyzed by enzymes. Cofactors, mostly metal ions or coenzymes, are inorganic and organic chemicals that assist enzymes during the catalysis of reactions. In the performed experiment the cofactor used was Magnesium in the form of Magnesium sulfate (MgSO4). Two replicates were prepared, one with the cofactor and the one without. Since respiration produces carbon dioxide, the rate of cellular respiration could be measured through the volume of the gas evolved. Thus, the hypothesis “If enzymes need cofactors to speed up its function, cofactors affect the rate of cellular respiration.” was formulated.

Substrates are molecules upon which an enzyme acts. Enzymes catalyze chemical reactions involving the substrate(s). A hypothesis such as “If the nature of substrates affects the cellular respiration of yeast, then the simpler the substrates, the faster the cellular respiration.” was derived out of reasoning. The following were used as substrates for the experiments: (1) starch—a polysaccharide; (2) lactose—milk sugar; (3) sucrose—table sugar; (4) glucose—a monosaccharide; (5) fructose—fruit sugar; and (6) distilled water.

The specific objectives of the study were

1. to cite means of measuring rate of cellular...


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Lagunzad, L.M. and Padolina, M.C.D. 2003. Functional Biology. Philippines. Vibal Publishing House, Inc. pp. 277.
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