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The aim of this investigation is to find out how different pH levels affect enzyme activity.

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Amylase PH Experiment Aim The aim of this investigation is to find out how different pH levels affect enzyme activity. Introduction Enzymes are globular proteins made up of amino acids strings that are twisted into elaborate shapes. They act as biological catalysts and are soluble. The shape of the enzyme is vital, as the substrate/s must fit exactly into the active site (a cavity) of the enzyme, rather like a lock and key. Once it is inside it forms an enzyme-substrate complex. Enzymes are either catabolic or anabolic. Catabolic enzymes break the substrate down into 2 or more products while an anabolic enzymes bond 2 or more substrates together to form one product. There is also an enzyme induced-fit theory which states that the enzyme changes shape to accommodate the substrates shape and then goes back to its original shape after the reaction is over. Enzymes never get used up so they keep on being re-used until the reaction is over or they get denatured. Enzymes are also specific; they only work on one type of enzyme, hence the specific shape of the active site. Enzymes are affected by changes in temperature and pH. The optimum temperature of enzymes is at 37C and they become denatured (because the bonds holding the amino acids strands begin to break which results in the change of the active site) ...read more.


I will use the following apparatus: Apparatus Precision 10cm Syringe �2mm 5 1cm Syringes �0.1mm Thermometer �0.2C 5 Test Tubes Amylase Beaker Dimple trays Universal Indicators Iodine solution with pipette Hydrochloric Acid Sodium Carbonate Starch solution Water Stopwatch I will keep the following controlled variables constant because they will affect the rate of reaction of the enzyme is not kept in check: Temperature of solution Substrate concentration Enzyme concentration The temperature will be kept at a constant 37C because that is optimum temperature for enzymes. In order to keep it at a constant 37C I will keep the test tubes containing the solution in warm water, which will be constantly checked, and if the temperature changes than more warm water will be added to make sure it stays at 37C. I will use a thermometer to check on the temperature. The substrate concentration will be kept the same, as I will be using the same starch solution and also the same amount with all the different pH values. It will be at 50% because half of the starch solution will be water. This will ensure that the enzymes have enough substrate to work with and so they will be working at maximum output. ...read more.


Then I will get the 1cm syringe and fill it up with the relative pH solution and empty it in its specific test tube, so the pH 5 solution will be in the pH 5 test tube. I will give the test tube a shake and simultaneously start the stopwatch. I will then use the 1cm test tube to fill up 0.1mm of the solution and when the time reaches 30s I will empty the contents of the syringe into the cavity. If the colour is black I will again fill 0.1mm of the solution and after another 30s I will repeat emptying the 0.1mm into the cavity to see if it turns mid-brown. Mid-brown will be my end point as this will notify me that the starch in the solution has been broken into sugar molecules hence the iodine solution not being blue/black anymore. I will write the time taken on a table and repeat this experiment 2 more time for pH 5. Thereafter I will start from the beginning with pH 6 and follow the instructions above, and likewise do the experiments for 7,8 and 9 three times each. I will keep an eye on the controlled variables to make sure they are constant in all experiments in order for it to be a more fair and reliable test. ?? ?? ?? ?? (c) Ismail Baiyat ...read more.

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