Enzymes In Respiring Yeast

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Enzymes are defined as biological catalysts since they are protein molecules that are produced by living cells. A catalyst is a substance which speeds up a chemical reaction but remains unchanged itself at the end. Enzymes are biological catalysts because they increase the rate of chemical reactions in cells which would otherwise be too slow to sustain life. Several factors affect the rate of enzyme reactions. These include: temperature, pH, enzyme concentration and substrate concentration.
In this experiment the effects of temperature on the enzymes in respiring yeast were being investigated. Firstly, 20 cm3 of yeast suspension was added to the boiling tube, T1. Next, it was stoppered using a rubber bung with a delivery tube attached to it.
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The yeast that was used in making this mixture contained enzymes. Due to the presence of the glucose, the enzymes had already started to respire. The enzymes in this respiring yeast would have broken down the glucose into carbon dioxide and ethanol. When stoppering the boiling tubes with the rubber bungs which had delivery tubes attached to them, it was ensured that they were of a sufficiently tight fit in order to make them airtight. This was done to prevent oxygen and other gases in the atmosphere from entering into the boiling tube. Therefore, any bubbling that was seen in the test-tubes would have been due to the carbon dioxide gas only.
The equation for the reaction is as follows:
WORDED EQUATION: enzymes in respiring yeast Glucose Carbon dioxide + Ethanol
CHEMICAL EQUATION: enzymes in respiring yeast C6H12O6 (aq) 2CO2 (g) + 2C2H5OH

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