The rate of enzyme reactions Essay Example for Free

The rate of enzyme reactions Essay Concentration- This affects the rate of this reaction because if there is more pepsin molecules within the mixture then there is more chance of collisions between pepsin and albumen molecules, which in turn increases the chance of the active site slotting on to the enzyme. Temperature- this affects the rate of reaction because different enzymes work best at different temperatures with the usual temperature being37. 2i c. If the temperature varies too much then the enzyme will not work to its full potential. As the temperature rises the enzymes begin to denature (deform so active site does not fit enzyme). The changes caused by denaturing are usually reversible but if they are too extreme then the changes are irreversible. pH- the pH affects the rate of reaction because the enzymes all work best at specific pHs depending on where they are used. Prediction- I predict that as the concentration increases so will the rate of reaction, I believe this because as the concentration increases the number of pepsin particles will increase making the chance of a collision and the active site slotting on to the enzyme. Scientific Theory- In this experiment our aim is to test the rate of reaction under certain conditions. Enzymes are biological catalysts, i. e. they speed up a reaction without being used up. Enzymes work best at specific temperature and pHs. They work best at 37. 2i c and depending on where the enzymes work different pHs. Pepsin the enzyme we are testing works best at pH 2. Each enzyme uses a lock and key system meaning they fit on the substance they are meant to break down and only that substance. Some examples of enzymes and its substrate are: Proteins- Protease Carbohydrates- Carbohydrase. Where the enzyme latches onto its substrate the area is called the active site. Safety- For safety in our experiment we will put goggles on when pouring acid so we do not get acid in our eyes. Fair Test- In our test the independent (changeable) variable we chose was the concentration of the acid. Our dependant (measured) variable is the time taken for the pepsin to break down the albumen. Therefore each time we must use the same amount of acid to keep the conditions the same. We must also keep the total volume of liquid the same, along with the amount of albumen each concentration is reacting on. Equipment- Test tube rack Hydrochloric acid Pepsin Albumen Water Boiling tube. Measuring Cylinder Stopwatch Water Bath Range Repeat- In our experiment we will use different concentrations to get a wide spread of results showing the difference in the rate of reaction with different concentrations. Here are the concentrations we will use and ho we made them- Concentration (%) Water (ml) Pepsin (ml) Albumen (ml) Hydrochloric Acid (ml)Â   In the experiment because there is a high chance of error we will repeat each concentration three times and take an average. Method- 1. Gather specified equipment, 2. Put 12 test tubes in test tube rack. 3. First put the required amount of acid in test tube, then put in the pepsin, then the water and when in a water bath bringing the temperature to 35i c then finally add the albumen. 4. Time how long it takes for the solution to clear completely. 5. Repeat each experiment three times. Results- Concentration Pepsin (%) Time for albumen to clear (secs) Rate of reaction (secs) Analysis- From my results and graph I can see a pattern, as the concentration increases so does the rate of reaction. My graph shows a curved line of best fit, which in the case of my results shows that as the concentration increases the rate of reaction does increase but the rate between each concentration gets lower as the concentrations rise. This pattern happens because although they may be a larger amount of pepsin molecules only one pepsin molecule can break each albumen molecule down. Eventually if the concentration is increased too much then it would have an adverse effect on the rate of reaction because they would be too many pepsin molecules colliding, reducing the amount latching onto albumen molecules so the rate would decrease. To work out the rate of reaction I did 1/t. In this equation t is the average time and then I multiplied it by 100 because the numbers were too small (0. 0s). My prediction was correct as the rate of reaction increases when the concentration is increased. Evaluation- In our experiment I believe I did quite well, because we have a nice curve on our graph and my prediction was justified. In our experiment the point which looks most like an anomaly is at 30%. I think this as it looks to be a bit low to go with our line of best fit. In our experiment I think that some of our results are wrong because we did not have the enzymes at the right temperature. To improve our experiment we could use light gates to see exactly when the albumen goes clear and we could keep all the enzymes and acids in a water bath so they are all at the same temperature. Our anomaly is about 0. 25secs from the line of best fit, which would make it around 6. 25secs. Extension In an extension I would test the effect of temperature on the rate of reaction. I predict that the enzyme will work best at around 40i c and as you move away from that temperature the reaction would slow. Range and Repeat- I will repeat each temperature three times and find the average just in case of a mistake. I will measure the temperature from 10i 50i in 10i intervals. Method- 1. Gather Chemicals etc. 2. Put each chemical in a water bath at specified temperature (10, 20, 30, 40, 50) 3. Get 15 test tubes. 4. When at specified temperature first put the required amount of acid in test tube, then put in the pepsin, then the water and finally the albumen. 5. Start timer. 6. When cleared stop timer. 7. Repeat three times. Karl Long Biology Coursework 1 Show preview only The above preview is unformatted text This student written piece of work is one of many that can be found in our GCSE Patterns of Behaviour section. r