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An investigation to find out if temperature affects the rate of reaction of amylase on starch.

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AN INVESTIGATION TO FIND OUT IF TEMPERATURE AFFECTS THE RATE OF REACTION OF AMYLASE ON STARCH Enzymes are large globular molecules of which vast majority are proteins in nature. The majority of reactions that occur in living organisms are enzyme-controlled. Without them, the rate of the reactions would be so slow as to cause serious, if not fatal, damage. The enzymes in our digestive system break down the complex substances into simpler ones that can be absorbed into the blood. Enzymes can be used in both anabolism (the build up of simple chemicals into complex ones), or more commonly, in catabolism (the breakdown of complex chemicals into simpler ones). Like all globular proteins, enzymes are made of long amino acid chains, within this some molecules are attracted to each other, so the chains folds in on themselves to form a 3D shape, with outer hydrophilic R groups ensuring solubility. Enzymes are known as biological catalysts, and therefore have catalytic properties, which means they can alter the rate of reaction without themselves undergoing a permanent change. Most chemical reactions require an initial input of energy, called the Activation Energy. ...read more.


Most enzymes work best at pH 7, which are in neutral conditions. Some, however, such as the protease pepsin works best in acidic conditions as it is found in the acidic conditions of the stomach and used along with stomach acid. It has an optimum of pH 2; hence it is well adapted for working in the very acidic environment of the stomach. On the other hand, Lipase works best in alkali conditions as its found working with bile in the intestines. Changes in pH affects the ionic bonds, which hold the enzyme in its shape. Enzyme contains many positive and negative charges. If extra charges are added, i.e. pH, the enzyme will denature as different charges will repel or attract each other. It may also affect the R groups in the active site, which form temporary bonds with the substrate. The pH is a measure of the concentrations of hydrogen ions in a solution. Lower the pH, the higher the hydrogen concentration. Hydrogen ions can interact with the R groups of amino acid; hence pH can affect the way in which they bond with each other and therefore affecting their 3D arrangement. ...read more.


I will be using many corrosive and irritant solutions, such as Iodine, which can stain hands or clothing. Therefore, I have decided that I must wear safety goggles throughout the experiment, and I should only remove them when I am 100% positive that I am far away from any form of danger. To ensure that I keep my clothes in a good condition and avoid any form of damage, I will be wearing a safety laboratory coat. I have also decided that I will be using a test tube holder for any test tubes or boiling tubes used during the experiment, and furthermore, I will use forceps if I decided to pick up test tubes from the water bath. I should always be very cautious while handling hot water. Results Once I have completed the preliminary experiment, I will use a Calibration curve to work out the Absorbance. Using the Calibration curve I can work out the rate of reaction, time taken in 2mins. I will use the following formula: Rate = substrate concentration � 2 e.g. if substrate concentration is 200cm�� 200 � 2 = 100mg�� min�� I believe that one set of results will not be enough to reach a valid conclusion, therefore I will repeat the experiment at least 2 more times. ...read more.

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