Enzyme used to break cell wall Essay Example for Free

Enzyme used to break cell wall Essay Aim To investigate the affect of Pectinase on the amount of juice produced from a stewed apple. I will investigate and explore the factors, which affect the rate at which juice is coming out of the stewed apple. There are many factors, which determine the rate at which reactions take place. The factors include temperature, concentration, surface area or pressure (if the substance is a gas) and a catalyst. However in this particular experiment I have chosen to investigate the rate of reaction when the concentration is the variable involved. Scientific Theories The theory of collisions Substances are made up particles. The particles in a particular substance can be atoms, ions or molecules. If two or more reactants collide with sufficient energy then a chemical reaction takes place producing a product. The particles must collide together hard enough to break the chemical bonds, kinetic energy is needed for this to occur. The initial energy or minimum energy that particles of reactants must have for them to react must have for them to react when they collide. The rate of reaction depends on how many reacting particles have this minimum energy. Heat is sometimes needed to start a reaction, which is referred to the activation energy. In many reactions often the products have less energy than the reactants. The more collisions and the harder the collisions between particles in a given time will result in the reaction speeding up. Temperature Faster collisions are only obtained by increasing the temperature. When the temperature is increased all the particles move quicker and collide more often. This will therefore speed up the rate of reaction. Surface Area (size of particles) If reactants are solid which is Magnesium in this particular experiment then if they are broken into smaller pieces this will increase the solids surface area. This will mean that the solution surrounding it in this case Hydrochloric acid will have more region to react on therefore creating more collisions between particles. This also will speed up the reaction. Concentration (or pressure if a gas) When a solution is made more concentrated which in this reaction will be to add more hydrochloric acid, which will mean there are more reactants to react with the magnesium therefore collisions are more likely. In gases though, increasing the pressure will mean the particles are more squashed up together consequently colliding more. This will speed up the rate of reaction. Catalyst This will speed up the reaction as it gives the reactants a surface to stick to where they can collide. Reactions only happen when particles collide with sufficient energy. From this theory as I am investigating the concentration of Pectinase we can say that if we increase the volume of Pectinase the rate at which the reaction takes place will increase, as the number of collision are more likely. Lock and Key Hypothesis Enzymes are substances that act as catalysts, in other words they increase the rate of reactions. Most enzymes are large protein molecules, with three-dimensional shapes. The substance with which the enzyme combines is known as the substrate. The reaction takes place on the surface of the enzyme called the active site. Enzyme molecules are usually very much larger than their substrates. The precise shape of the active site is important because it is complimentary to the shape of the substrate molecule, which fits into the active site, which is known as the lock and key mechanism. In this particular experiment the active site of the enzyme has a specific shape for the Pectin, which only it can fit into. The substrate is the pectin and the enzyme is the pectinase. In this specific experiment, we can say that if we increase the volume of Pectinase (the enzyme) the rate at which the pectin interacts with the active site of the enzyme will increase, therefore the rate at which the juice comes out of the stewed apple will also increase. Enzyme Activity 0i C 45i C Enzymes are usually damaged by temperatures above about 45i c, and as the graph shows, their activity drops off sharply when the temperature gets too high. Preliminary Work. In class we have performed a similar experiment involving the rate at which juice comes out of a stewed apple. However this time there were only two stewed apples, one solution contained the enzyme pectinase and the other without it. From doing this experiment, I found that the solution with Pectinase clearly produced more juice at a faster rate, than the solution without Pectinase. This proves that enzymes will greatly increase the rate of formation of the product. From doing that experiment I learnt a lot of things, which I would have to change in my final experiment, for example a more accurate measuring cylinder. Prediction. I predict that if I double the concentration of Pectinase, the rate at which the juice comes out of the stewed apple will also double. And the reaction time will be cut in half. This is because as the volumes of Pectinase will increases therefore there will be more Pectin interacting with the active site of Pectinase, therefore more cell walls will be breaking and more juice will be produced. Also, because of the simple concept that before particles can react they must collide, therefore there will be more particles in a smaller volume therefore collision between particles will be more likely and consequently the reaction will speed up. I can also predict that if I half the concentration of Pectinase, this will also half the rate at which the reaction takes place and the time taken for the reaction to take place will double. This is because the decreased number of particles also means that the chance of collision will also reduce. Therefore the time taken for the cell wall in the apple to break will decrease and result in less juice being produced over a certain period of time. I also predict that the amount 0of juice produced will be proportional to the time. Apparatus Pectinase (enzyme used to break cell wall) 4 100cmi beakers 10cmi measuring cylinder Stewed Apples (chopped up) Filer paper Water Stop- clock (to record the amount of juice being produced) Scale (used to measure the mass of the steed apples) Funnel Syringe Variables The variable, which will be changed in this experiment to alter the rate of reaction, is concentration. At least five readings are needed in order to draw a graph and to have significant amount of results, to prove he prediction. The concentration of Pectinase will change, as water will be added to dilute it. The total volume of Pectinase and water in each experiment will always be 5cmi making it a fair test. The table below shows the different concentrations used in the experiment Concentration of Pectinase Concentration of Water 5cmi 0cmi 4cmi 1cmi 3cmi 2cmi 2cmi 3cmi 1cmi 4cmi 0cmi 5cmi Plan The apparatus will firstly be collected and set up. The stewed apple will be weighed in a 100cmi beaker. The volume of Pectinase and water will be taken out of the container using a syringe. The Pectinase and water will be measured using a measuring cylinder (10cmi)