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To investigate the effect of temperature on enzyme activity

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Introduction

nzyme Activity Aim - To investigate the effect of temperature on enzyme activity Yeast + hydrogen peroxide yeast + water + oxygen Planning Introduction Enzymes are extraordinarily efficient. Minute quantities of an enzyme can accomplish at low temperatures what would require violent reagents and high temperatures by ordinary chemical means. About 30g of pure crystalline pepsin, for example, would be capable of digesting nearly 2 metric tons of egg white in a few hours. As a rule, enzymes do not attack living cells. As soon as a cell dies, however, enzymes that break down protein rapidly digest it. The resistance of the living cell is due to the enzyme's inability to pass through the membrane of the cell as long as the cell lives. When the cell dies, its membrane becomes permeable, and the enzyme can then enter the cell and destroy the protein within it. Some cells also contain enzyme inhibitors, known as antienzymes, which prevent the action of an enzyme upon a substrate. Prediction An enzyme is a protein molecule that speeds up chemical reactions in all living things. ...read more.

Middle

Controlled Variables: Same amounts of yeast 5ml hydrogen peroxide 15ml Types of liquid Water, Hydrogen Peroxide, and Yeast solution Range of temperatures 20oC - 60oC. The temperatures must be kept as exact as possible as yeast is very receptive to changes in temperature. Volume of water in the measuring cylinder 100.0ml Room temperature 25�C approximately Readings taken every 2 minutes Same set up and equipment see diagram Repeat 5 times Same amount of water in bath cylinder Length of experiment 14 minutes Apparatus Measuring cylinder To hold 100ml of water. This was thoroughly cleaned with tap water beforehand to ensure that the water was not contaminated with anything. This may have led to anomalous results in the long-term. Clay Beehive To provide somewhere to connect the pipe from the mixture to the water. It also acted as a ledge to hold the measuring cylinder as it stood upside-down. Tub To hold water and everything in place. Stopclock To time experiment. I ensured that the experiment was timed as soon as it began because if it had not, then the results may have been inaccurate. ...read more.

Conclusion

At this point, it was very important that the two substances are kept apart, because if they were mixed they would begin to react. The boiling tubes were both cleaned to ensure they were free of chemicals that could react with the chemicals used for the experiment and produce anomalous results. Both liquids are poured into a conical flask, and the bung with an attached tube is quickly fixed on and the stopclock is started. This operation needs to be practised before the experiment was conducted to ensure it is done as quickly as possible. The hydrogen peroxide and yeast solution will start reacting as soon as they come into contact. The tube is connected to the clay beehive and measuring cylinder, which were both already prepared in the water. How much oxygen had been reacted and had travelled down the pipe into the 100ml of water in the measuring cylinder is noted down every two minutes. The measuring tube must be changed from time to time when it fills up with oxygen. A filled tube must be carefully inserted into the water, and slid across the hole in the beehive while the filled tube is being removed. After fourteen minutes the reaction has stopped completely. ...read more.

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