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Investigating factors which affect the rate of the Amylase Enzyme in converting Starch to Maltose

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Introduction

Individual Investigation: Investigating factors which affect the rate of the Amylase Enzyme in converting Starch to Maltose By Osman Khan Lee 13 Aim The aim of my investigation is to see what factors affect the rate of reaction of the enzyme amylase. These factors will be temperature, effect of an inhibitor and the enzyme concentration Making the Concentrations of the Chemicals Variable 1- Temperature Temperature (*c) Amylase Concentration (%) Starch Concentration (%) Reading Transmission of light after __ minutes 1 2 3 4 5 0 5 1 1 2 3 15 5 1 1 2 3 30 5 1 1 2 3 45 5 1 1 2 3 60 5 1 1 2 3 The result of amylase on starch is the conversion to maltose. This result can be detected by using Benedict's solution, which will start blue/black and turn into a brick-red precipitate. Due to this precipitate forming, the transmission of light through it will decrease. Therefore using a colorimeter I will be able to detect how the transmission of light through the sample decreases. In order to do this I must take samples from the solution at various intervals. It is therefore essential that I have enough starting solution to carry out the whole experiment. - The table above is a rough table showing the results I intend to collect. As you can see there are, in total, 15 readings for each temperature and therefore 75 readings in total. - The cuvette volume, which will measure the light transmission, is approximately 3cm3. I will therefore allow for spillage etc and assume that for each sample I require 4cm3. - Therefore in total I will need 75 x 4cm3 of solution, which is 300cm3. This will be enough solution to last me the whole temperature variable. Now that I know this I can begin to work out how much amylase and starch I will require. ...read more.

Middle

Therefore to make 1% starch solution I will need to have: 1 part starch 100%: 100 parts water Therefore I will have 2cm3 starch 100% and 200cm3 water. This will give me a little over the required amount. As the copper sulphate concentrations are so small I will only require maybe 1cm3 of copper sulphate solution. To make 0.005% copper sulphate concentration: 1 part Variable 4- Starch Concentration My 4th variable will be to see how the action of amylase is affected by substrate concentration. Below is a rough table showing some of the main details I will try and obtain. Starch Concentration Amylase Concentration Reading Transmission of light after __ minutes (%) (%) 1 2 3 4 5 5 5 1 2 3 4 5 1 2 3 3 5 1 2 3 2 5 1 2 3 1 5 1 2 3 0 5 1 2 3 The total solution required for each concentration is: 15 x 4cm3 (max cuvette volume) = 60cm3 As the enzyme and substrate and being added in equal quantities I will require 30cm3 starch solution and 30cm3 amylase solution for each concentration Starch 5% = 1 part starch 100%: 20 parts water Therefore each part will be: 30 / 21 = 1.43cm3 Once again this is a difficult volume to measure so I will make extra solution and make one part equal to 2cm3. Therefore: 1 x 2cm3 starch 100% = 2cm3 20 x 2cm water = 40cm3 Starch 4% = 1 part starch 100%: 25 parts water Therefore each part will be: 30 / 26 = 1.15cm3 This is also difficult to make so I shall make 1 part equal to 2cm3. Therefore: 1 x 2cm3 starch 100% = 2cm3 25 x 2 cm3 water = 50cm3 Starch 3% = 1 part starch 100%: 33 parts water Therefore each part will be: 30 / 34 = 0.88cm3 Once again this is an awkward volume to make so I shall make 1 part equal to 1cm3. ...read more.

Conclusion

For a reaction to occur the particles must collide with a certain minimum kinetic energy. The size of this kinetic energy needed varies between reactions due to different bond enthalpies. This minimum energy is known as the activation energy. The enthalpy profile of a reaction looks like the one below In a solution like mine, which will contain amylase enzymes and starch, the particles have a range of different kinetic energy. Most of the particles will be moving at moderate speeds, others will have slightly greater kinetic energy and some will have slightly less. When the temperature of the reactants rises, they move around faster and have a greater amount of kinetic energy. This means that of those particles that collide with one another, the amount of energy of the impact is more likely to exceed the minimum kinetic energy required. The amylase enzyme works by lowering this minimum energy, or activation energy, further, so that a larger number of molecules have the required energy and can cause a reaction. This is illustrated in the diagram below. The above diagram shows that only a small proportion of the molecules have the energy E to overcome the activation energy (which in this case is 50kg mol-1), and to cause a reaction to occur. If we now however raise the temperature the graph will look like the one shown below. 2Distribution curves showing effect of a temperature rise of 10K on the proportion of reactions with greater than 50kg mol-1 From the graph you can see that by increasing the temperature by 10 Kelvins the graph has shifted to the right- i.e. there is a higher average kinetic energy of each particle. There is a much higher proportion of molecules with greater than 50kg mol-1 which means more collisions will be successful enough for a reaction to occur. Yet to talk about effects of inhibitor and concentration variables. 1 Diagram taken from Biology 1 Advanced Sciences page 42 by Mary Jones, Richard Fosbery and Dennis Taylor Diagram taken from Salters Advanced Chemistry: Chemical Ideas 10.2 page 225 ...read more.

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