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Investigation into the effect of enzyme concentration of catalysers of sucrose by sucrase.

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Investigation into the effect of enzyme concentration of catalysers of sucrose by sucrase Planning Aim: I aim to find out the effect of enzyme concentration on the substrate. I will try to find out how fast the substrate sucrose is broken down using different concentrations of sucrase, to see if there is a link between enzyme concentration and the rate at which the substrate is broken down. An enzyme is made of protein, they are protein molecules which are called a biological catalyst. These molecules speed up chemical reactions and remain unchanged when the reaction is finished. Enzymes have an active site, this is a place where another molecule or molecules can bind to. These molecules are the substrate of the enzyme. The shape of the enzymes active site will allow the substrate to fit onto it. The substrate is held in place by temporary bond that form between the enzyme and the substrate, the bonds form between the R-groups of the enzymes amino acids and the substrate. Only one type of enzyme will work on one type of substrate molecule. This is because the shape of the enzymes active site will only fit the molecule which will fit into its active site. The enzymes catalyse reactions where substrate molecules are split into two or more molecules. In this case Sucrose glucose + Fructose Sucrose is broken down into two molecules by sucrase into glucose and fructose which are reducing sugars. When the reaction is finished, the products leave the active site and the enzyme is unchanged, then it is ready to receive another substrate molecule. Factors that can affect the reaction rate are the temperature, enzyme concentration and pH. ...read more.


I will then choose to concentrations which I think don't have a very big difference in time, I will then repeat the experiment ten times on these two concentrations, I will do this so that I can do a statistical test on them. The statistical test will tell me if there is a difference between the two concentrations or if they are the same. I chose to do this method because it worked well when I done my preliminary experiment, so I will use it to do my final experiment. To do different concentrations of sucrase I will have to dilute them. * I will dilute the concentration of sucrase by using distilled water. I will use this because it doesn't contain any chemicals. * I will use a 5cm3 syringe to put the correct amount of sucrase into the test tube. * Then I will use a different syringe to put in the right amount of water to get the right dilution. * To get 1% enzyme concentration I will use 5cm3 of sucrase. * To get 0.8% enzyme concentration I will mix 4cm3 of sucrase and 1cm3 of distilled water. * To get 0.6% enzyme concentration I will mix 3cm3 of sucrase and 2cm3 of distilled water. * To get 0.4% enzyme concentration I will mix 2cm3 of sucrase and 3cm3 of distilled water. * To get 0.2% enzyme concentration I will mix 1cm3 of sucrase and 4cm3 of distilled water. Apparatus: Apparatus Why I chose this apparatus Test tubes Because they can be easily heated and moved around Test tube rack Because the test tubes wont fall over and I will need to set up a lot of test tubes Stop watches Because the are very reliable and accurate, it would give accurate timing Syringe (5cm3 , 1cm3 ) ...read more.


The variation in temperature could have caused an anomalous result. The variations in the amount of benedict's solution used could have cause reaction to take longer to end. I think the reliability of the evidence is good. Every different concentration was put under the same conditions and each solution was measured in the same way. The main source of error was the way that I measured the end point. I used a sample to measure the end point, and I judged the colours with my eyes. The colours could have been slightly different but I couldn't tell. By judging the end point this way, I might have stopped each reaction in different places, meaning each reaction had different end points, this would make my results not very reliable. The sample would also still be reacting, so it would get darker, so near the end of the experiment I would be stopping the reactions at a longer point. I could improved the way I judged the end point by using a colorimeter. I would tell me the exact colour of the solution, so I could stop each reaction at the same place, this would make my experiment much more accurate and reliable. The strong correlation from the data sown in the graphs and in the tables shows that the limitations that have been described has not had a great effect on my result, and my conclusion therefore have a high level of validity. I drew a graph with error bars, which shows that there is no overlap with different concentrations of sucrase. This shows that as the concentration of sucrase increases the reaction time is faster. 1. Jones, M. (ed).(2000).Biology 1. University press: Cambridge. ISBN: 0 521 78719 X 2. Introduction to Enzymes. (2003). Worthington biochem. URL: http://www.worthington-biochem.com/IntroBiochem/effectspH.html 3. Green, N.P., Taylor, D.J. Biological Science, Cambridge University Press, 1984. James Clothier 1 ...read more.

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