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Investigation into the factors affecting the rate of enzyme reactions.

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Biology- Investigation into the factors affecting the rate of enzyme reactions Aim- we are going to investigate the concentration of pepsin affecting the rate of reaction between pepsin and albumen (egg white). Variables- > 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 being37.2�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 pH's depending on where they are used. ...read more.


Here are the concentrations we will use and ho we made them- Concentration (%) Water (ml) Pepsin (ml) Albumen (ml) Hydrochloric Acid (ml) 40 0.00 1.00 1.00 0.50 30 0.25 0.75 1.00 0.50 20 0.50 0.50 1.00 0.50 10 0.75 0.25 1.00 0.50 0 1.00 0.00 1.00 0.50 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 35�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) 1/t R o R *100 1 2 3 Ave 40 15.00 12.00 15.00 14.00 0.07 7.00 30 23.00 20.00 10.00 17.67 0.06 6.00 20 19.00 22.00 22.00 21.00 0.05 5.00 10 35.00 31.00 29.00 31.67 0.03 3.00 0 N/r N/r N/r N/r N/r N/r N/r= no reaction. ...read more.


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 40�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 10�- 50� in 10� 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 ...read more.

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