Hydrolysis of Starch Essays

Hydrolysis of Starch Essays Hydrolysis of Starch Essay Hydrolysis of Starch Essay Hypothesis: Temperature change (positive) will almost certainly have the effect of catalysing the starch which is being catalysed by the amylase solution, meaning it will speed up the entire reaction which is already being catalysed. Enzyme activity will be profusely affected whatever the temperature change is. Science Reasoning For Hypothesis: Proteins have biological catalysts (a substance which speeds up the reaction without becoming part of the product). They are called enzymes which when binding to the reactants of the reaction theyre catalysing, cause the amount of activation energy to decrease, causing the reactions speed to increase. A large activation energy amounts to a slower reaction because the substrate needs to surpass the initial activation energy, so a lower one will result in a faster reaction. An enzyme and a product are left at the end of a chemical reaction with a substrate and reactant. Interactions between enzymes and substrates are noticeably weak, so a large surface area is usually required, this is to increase the chances of reactions. Metabolic reactions are also catalysed by enzymes such as respiration and digestion (of foods) theyre also receptors and membrane pumps amongst many other proteins (every single metabolic reaction). Amylase is a globular protein as all enzymes are, the active site being where the reaction takes place. The reaction rate will almost always increase at optimum temperature but only up to the optimum temperature, which is in exact proportion to the temperature rise. This is because both the substrate and enzyme molecules in any particular reaction have more kinetic energy, therefore the particles have a higher chance of actually colliding with one another (so reaction speed increases). The Substrate molecule is held in position by amino acids which occupy the a certain space in the active site this occurs whilst the reaction is in progress. Any other molecules simply wont fit into the active site the enzymes specific purpose is for one sole reaction molecules of a different shape simply wont connect to the active site. The enzyme will then speed up the reaction on its surface, the product is then released. All chemical changes cause a product to be formed from a substrate. In humans [most] the enzymes will be at the optimal temperature when the bodys heat is regulated to approximately 40C ( fourty Degrees Celsius ), where the usually temperature is somewhere around 37C. Hydrogen bonds are broken down by thermal energy the secondary structure and tertiary structure of the enzymes are held together by hydrogen bonding, the active site can no longer have a substrate bound to it because of the disfigurement of the active site. This regulation of 37C acts as a kind of safety mechanism because minimal changes above 40c (optimum level) causes denture of the enzymes an irreversible damage ( at high C) which will stop them from working properly, if not then altogether. The optimum pH for enzymes is 7 any change to this and damage can also be done to enzymes, the charge will change so the hydrogen and amino acid bonds will disconnect. Method: Switch on the colorimeter to warm up, secondly to carry out serial dilutions to make starch solution with a range of concentrations: Ill take 12 boiling tubes, and in one tube measure 10cm3 of 0.5% starch solution, in test tube two 10 centimetres of the 0.5% starch solution and add 10cm3 water and mix. In tube 3 measure 10cm3 solution from tube 2 and mix with cm3 of water, in tube 4 measure 10cm3 of solution from tube 3 and mix with 10cm3 of water and so one. With tube 12 Ill discard 10cm3 of water, I should then have 10cm3 in each tube. Ill make up twelve colorimeter tubes of dilute iodine. Ill draw up 4cm3 in a 10cm3 to proceed with the enzyme reaction (using a pipette / syringe). One cm3 of amylase will be draw upinto the same syringe plus 2cm3 air, Ill mix by means of inversion and then start my stop clock and put 2 drops of the reaction mixture in the first indention tile. Hopefully the iodine will turn blue. Every 30 seconds this process will be repeated, if my reaction is finished, (after placing starch to the iodine in subsequent solutions in the indentation tile ), the enzyme will be diluted after eight minutes. Three and four (of the above) will be repeated for the other starch solutions, the frequency sample will be increased if the reaction fishes quickly, need to keep reaction mixture throughout. Will plot a graph of substrate concentration against time to complete the overall reaction, and a second graph will be plotted against the rate of reaction. A standard curve needs to be plotted which is a graph of concentration percentage against absorbency, this will be before the experiment has started. Temperature will be the independent variable in my experiment, five of the temperatures will test the effectiveness of the reaction. One of the fixed variables will be reaction volume. The dependant variable are the substrates and enzyme concentrations. A list of these will be made for each experiment. Prediction: I predict that product yield will be highest when the temperature is between 37 and 40c due to these being the near optimum and optimum temperatures for the enzymes and substrates to react with one other (as explained above). Risk Assessment: Laboratory safety garments, glasses and plastic gloves must be worn at all times during the experiment due to the [very] harmful chemicals involved (such as iodine, an irritant).Any physical damage done to myself or anyone participating in this experiment should be attended to by medical personal The breaking of certain glass objects may occur this should be cleared up with a dust pan and brush or whatever is available for this type of action. Apparatus list: Equipment Ill be using in this experiments as follows: Graduated glass pipette or [secondary choice] syringe possibly: Because in my preliminary experiments the syringes were not accurate enough, which meant it was difficulty to measure the solution properly. Boiling tubes which sufficient enough to carry out experiment properly. Heated water bath: The temperature should stay at a regular level when using the water bath. Thermometers will be put in the boiling tube with the substrates and enzymes. This is a precaution to make sure the water bath is working adequately, the temperature must be regulated. An indention tile to place the starch solution on. A stop-clock will be needed to time the experiment. Colorimeter tubes are tubes that fit inside the colorimeter with some liquid inside them. Colorimeter: A colorimeter measures the light absorbed by a coloured/cloudy solution. This is known as absorbency and is shown in arbitrary units. The colorimeter measures the light that is transmitted through a solution. This is known as transmission and is expressed in a percentage form. A colorimeter works using light rays from a tungsten bulb. A filter is put between the sample and the light source. For this experiment I will be using a red filter, as my solution is blue. This filters out certain colour densities.