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What Affects the Enzyme Catalase?

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Shimon Simon 10SI 10/07/2002 Biology Coursework What Affects the Enzyme Catalase? Background information: An enzyme is a large protein that acts as a biological catalyst and which changes the rate of a reaction. It provides an active site which is an environment where a reaction can take place this is made up of amino acids. The structure and shape of the substrate, the structure and shape of an enzyme and the substance upon which the enzyme works all have to match exactly. This enables the substrate to bind, but it can't do this if the shapes of the two are different. An enzyme itself will not be affected by the reaction and if the reactants are released the enzyme can be bound with a new substrate. The enzyme I am investigating is catalase. Catalase is made in all organisms including yeast cells which will be used for my experiment. Catalase breaks down Hydrogen peroxide into water and oxygen. Hydrogen Peroxide Catalase = Water + Oxygen 2H2O2 H 2O O 2 There are many different factors which affect how catalase works. One of these is the temperature of the substrate. By increasing the temperature I will increase the rate of reaction. This is explained with the use of collision theory. ...read more.


If the concentration is trebled then so will the rate of reaction. The basis of this prediction can be shown by looking at what the concentration does. A smaller concentration will mean that the molecules of Hydrogen peroxide will be less since there is more water. There will therefore not be many successful collisions between the enzyme and Hydrogen peroxide. By doubling the concentration there will be double the amount of hydrogen peroxide per cm3 less water and so double the amount of successful collisions, double the amount of oxygen and double the speed so half the time due to more successful collisions per second. By increasing the concentration each time by a factor I should be able o observe a constant. This is my preliminary results while using 10cm3 yeast trying each concentration twice as follows: Volume of Oxygen collected (cm3) Concentration of Hydrogen peroxide in total of 20cm3 (Hydrogen Peroxide: water) 5:15 (1/4) 10:10(1/2) 15:5(3/4) 20:0 (1) Time (minutes/seconds) 1st 2nd average 1st 2nd average 1st 2nd average 1st 2nd average 0.30 9 7 8 15 19 17 26 22 24 27 33 30 1 10 12 11 23 23 23 35 33 34 44 46 45 1.30 16 14 15 31 29 30 43 45 44 56 ...read more.


There are plenty of values therefore to make a mathematical analysis. I found that 20cm3 of solution was not enough in my preliminary work. Method: I will fill the plastic tub halfway with water and the 200cm3 measuring cylinder to the brim with water. I shall place the measuring cylinder in the tub with the opening at the bottom making sure no water is lost from the measuring cylinder. I will place one end of the delivery tube in the cylinder and attach the other to the bung. I will then put 10ml of yeast suspension in the conical flask. I shall then have to pour the hydrogen peroxide and water in the flask close the bung and get someone else to start the stop clock. Time permitting I will do this 3 times for each concentration and take an average. This should give me accurate results for which to make my mathematical analysis. I will change only the concentration of hydrogen peroxide and leave all other variables the same therefore making a fair test. I will make sure I do not come in contact with Hydrogen peroxide since when it reacts with water it forms caustic soda. Other then this the experiment is quite safe. ...read more.

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