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Find out if enzymes work faster or slower at different temperatures.

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Nick Spong Biology 10/11/03 Introduction This is the plan and evaluation of an experiment to find out if enzymes work faster or slower at different temperatures. We will be timing how long it takes to see a cross through 20cm3 of Marvel milk solution at three different temperatures. We will be using the enzyme neutrase to break down Marvel milk. Hypothesis My hypothesis (theory) is that at temperatures over 40�c the neutrase will be increasingly denatured and the milk will not clarify. Under 40�c the neutrase will be slowed down. However I predict that at 40�c the neutrase will be working well as this temperature is near its optimum temperature and so the milk will decolorize the fastest. I have made my prediction based on the following evidence: The reason that the milk will decolorize or do anything at all is because neutrase is an enzyme. Enzymes are biological catalysts. This means that they are a biological life form that catalyses (speeds up) a process. They have an optimum temperature and pH. Both of these have to be almost exactly right, otherwise their performance deteriorates rapidly. In high temperatures the enzyme will be denatured and will not work even if you bring the temperature back down. However, at low temperatures, and low and high pH's, all you have to do is bring the environment close to the enzyme's optimum environment and the enzyme will work again without any loss in performance. We will be using a 2% solution of neutrase, this means it is 98% water. If we increased the concentration we would be increasing the amount of neutrase and it would have exactly the same effect as increasing the volume of the neutrase and water solution. Overall the reaction would be faster as more particles mean more collisions. So if we increase the amount of enzymes in solution, we will have more collisions of enzyme and substrate and then the substrate will break down into the products faster, so we must keep the concentration constant to make the test fair. ...read more.


We will record our results to the nearest hundredth of a second as this is the smallest amount of time that the stop clock will display. To make sure the test is fair we will: Use a buffer solution to make sure the pH is the same for all of the experiments. Try and measure accurately and with the same equipment for each of the experiments. The concentration of both will need to be the same but we cannot do anything to control this as we will be given the solution of milk and neutrase and will not be involved in any way in creating the 2% solution. We will use the same person to judge when the mixture is decolorized, as a different person could have worse/better eyesight than the other and this would result in inaccurate results. To keep the temperatures as near to the target temperature as possible, we will leave them in the water bath/ice tray for the same amount of time. We will repeat all 5 experiments 3 times and then get rid of all obvious anomalous results. Only when we have results that seem consistent will we take the average figure and use this as a final result. Make sure we wash all of the equipment before we start the next test. We will change the variable so we readings at 10, 35, 40, 60 & 80oc. Each reading will be taken 3 times. Some safety precautions I will need to take are: Wear goggles to protect my eyes. Wear gloves to protect my hands Do not sit down. Do not run with chemicals or glass. Do not eat or drink whilst in the lab. When we have collected the results in a table we will analyze them and then present them in a graph and a table. Results Table Temp. (oc) Actual Temp (oc Enzyme) Actual Temp (oc Marvel Milk) ...read more.


We will then begin the experiment. We will repeat the experiment at 1 degree intervals from -10oc to 100oc we will do each 1o interval experiment 5 times. We will then discard any anomalous readings and take an average of the readings left. We will place the cuvette into the colorimeter and put a funnel into the cuvette. We will then go to collect 1cm3 of Marvel Milk using a 1cm3 gradated pipette. We will then collect a 0.1cm3 solution of enzyme using a 1cm3 syringe with 0.1cm3 graduations. With a different syringe we will collect 0.1cm3 of a pH 7 buffer solution. We will use such small amounts as the cuvettes for the colorimeter are very small and cannot hold much liquid. We will then use a data logger with two probes to check the temperature of the enzyme and substrate before adding them together with the buffer solution into the cuvette. Once they are in the cuvette we will put the cuvette with the reactants into the colorimeter (which will already have a sample of the solvent, water, in it) and at the same time start a stopclock. We will then see how long it takes for the colorimeter to read 95%. Once it reads 95% we will stop the stopclock and take down a reading off of the stopclock. We will then put the cuvette in for washing and take out another cuvette. We will then wash out the graduated pipette and the syringe ready for the next experiment. We will use the same water in the colorimeter to make sure that that does not add another possible error. To get our results we will be measuring how long it takes for the milk to decolorize at 1o intervals between -10 and 100oc. This will give us an idea of the enzymes reactivity. I expect that the results would put the enzymes optimum temperature at around 37oc. Any higher or lower and the overall time will go up due to the enzymes being denatured or the energy being taken away. ...read more.

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Here's what a teacher thought of this essay

5 star(s)

This is a well structured and detailed report.
1. The background section is well written, although the sources of information need to be referenced
2. The preliminary section sets up the investigation well
3. The conclusion uses data and explains the results
4. The evaluation shows a good understanding of scientific practises

Marked by teacher Luke Smithen 17/09/2013

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