Investigating the effect of the Temperature on the Enzyme Catalase when it reacts with Hydrogen peroxide.

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PLANNING EXPERIMENTAL PROCEDURES

Title of Investigation: Investigating the effect of the Temperature on the Enzyme Catalase when it reacts with Hydrogen peroxide.

1.Make a Prediction

I predict that by increasing the temperature it would speed up the rate of the chemical reaction of the enzyme catalase. The higher the temperature the faster the reaction would occur. As the temperature first gets heated the particles move slowly, as the temperature gradually increases the particles start to move faster and faster and collide more often with enough kinetic energy.

2.Use your knowledge of science to explain why you made the prediction.

Enzymes are biological catalyst, which speed up the rate of a Chemical reaction. Enzymes are found in every living cell, different biochemical reactions take place rapidly and simultaneously. An enzyme can be used over and over again without being chemically changed itself. Most enzymes are protein molecule, which are highly specific at catalysing one type of chemical reaction. Without enzymes these reactions would occur too slowly or not at all, and no life would be possible. All living cells make enzymes, but enzymes are not alive. Enzyme molecules function by altering other molecules. Enzymes combine with substrate molecules to form a complex molecular structure in which chemical reactions take place. The enzyme, which remains unchanged, then separates from the product of the reaction. All the reaction that happens inside the living cells goes on at a relatively low temperature. All the reactions that take place in the cells are called metabolic reactions. Every metabolic reaction is controlled by an enzyme, they are controlled in such way that useful products are made and they also get rid of waste materials. The first enzyme to be discovered was amylase, which catalyses the conversion of starch to Maltose. Enzymes work at a suitable temperature and this is known as the Optimum temperature.

The enzyme catalase is a Peroxisome which catalyses the breakdown of hydrogen peroxide, a by-product of aerobic respiration. Hydrogen peroxide is a toxic and a corrosive substance, which can accumulate. In some cases the hydrogen peroxide is used to oxidise other molecules. For example about half of the ethanol that we consume is oxidised in the peroxisomes of our liver cells. This is one of the several ways in which our liver cell detoxifies unwanted molecules. Catalase is an enzyme found in food such as potato and liver. It is used for removing hydrogen peroxide from the cells. Catalase speeds up the decomposition of hydrogen peroxide into water and oxygen. It is able to speed up the decomposition of hydrogen peroxide because of the shape of the hydrogen peroxide molecule. The type of reaction where a molecule is broken down into smaller pieces is called a catabolic reaction.

Why I made the prediction is because, changing the temperature would speed up the rate of the chemical reaction of the enzyme because, when heating any substance the heat supplies a form of kinetic energy to the reacting molecules, making the molecules move rapidly. There is an increased chance of the molecules colliding against each other. At an increased temperature more collisions will be taking place because as I explained above the heat supplies a form of energy to every molecules that is present, this energy allows the molecules to collide against each other, as they collide against each other heat energy is transferred from one molecule to another. This increases the rate of the reaction because the particles have enough energy to react. However heat energy also increases the vibration of the atoms, which make up the enzyme molecule. If the vibration becomes too violent then the chemical bonds in the enzyme break up. As the vibration becomes violent and the chemical bonds break up this means that the enzyme has denatured and changed shape at a high temperature. The effect of this is that if the enzyme denatures then the rate of reaction will gradually decrease because there will be less particles taking place which suggest that there will less collisions between the particles.

3.What scientific knowledge do you have which will help you plan what to do?

        I have good scientific knowledge, which can help me through out this experiment, because this will make the task much easier to do. Before hand doing this experiment we were given the reaction that catalase speeds up.

        Hydrogen peroxide                    Water + Oxygen

The substrate that catalase recognises was the Hydrogen Peroxide, and the products formed are Water and Oxygen. The background theory to all this is that once the filter paper is dipped into the catalase solution, the catalase particles are present in the filter paper, these particles inside the filter paper move randomly, each particles collide against each other transferring energy. Once the filter paper is dipped into the solution it is then taken out and left over the top of the catalase solution for a short while so that the extra catalase solution is dropped off. The filter paper is then put into the hydrogen peroxide solution, as the catalase solution comes in contact with the hydrogen peroxide both of the particles from the different solution combine together colliding against each other transferring heat energy. Once the catalase solution is in contact with the hydrogen peroxide the gas oxygen is formed. The filter paper sinks to the bottom of the hydrogen peroxide solution forming oxygen, it’s the gas oxygen that makes the filter paper float back to the top. Now if the filter paper always has the same area, then it will take the same amount of oxygen gas to make it rise back up to the top. All this colliding of particles that is taking place has a theory background to it, this is known as the Collision theory. The rate of reaction depends on how hard the reacting particles collide with each other. The harder and more often the particles collide the faster the reaction. Increasing the number of collisions or increasing the speed of the collisions will increase the rate of reaction.

Little diagram of the temperature particles.

As the temperature increases, there

is more collision and the particles

react faster with enough energy.

Low Temperature                        High Temperature        

Behind all this theory is the Lock and Key theory. A lock and key theory is used to explain the way an enzyme and a substrate work. Enzymes and substrate have the same similarities of how a lock and key works.

  • Only one enzyme does one job and this reacts with a specific substrate. The shape of the enzyme is specific and only one substrate can fit into this and not any other enzymes.
  • Once the enzyme reacts with the substrate it releases the products and repeats this process again with the same enzyme molecule. For example the enzyme catalase reacts with hydrogen peroxide forming the products water and oxygen and this process is repeated over and over again with the same enzyme molecule.
  • An enzyme does one of the two things, it either splits a complex substrate molecule into two simple ones or it either joins the two complex substrate into one large molecule.
  •  The part of the enzyme that reacts with the substrate is known as the active centre or site. It is very important that this part of the enzyme molecule does not change shape. If however the shape is changed then the substrate will not react, which means that the enzyme molecule has denatured and changed shape, which shows that the lock will not fit into the key.  
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Diagram of the lock and key theory.

4.Describe in detail, how the experiment will be carried. Someone else following your plans should be able to carry it out exactly as you would do. Include an apparatus list.

        The experiment will be carried out by one or two person (yet unknown).

  • We will be adding 15 cm3 of Hydrogen Peroxide into the flat bottomed tube (specimen tube)
  • Next we will be cutting out small circles of filter paper, the filter paper will be all the same size because we will be using the same whole puncher ...

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